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Impact of Tetrabutylammonium on the Oxidation of Bromide by Ozone
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  • Shuzhen Chen
    Shuzhen Chen
    Laboratory of Environmental Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland
    Institute of Atmospheric and Climate Sciences, ETH Zürich, 8006 Zürich, Switzerland
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  • Luca Artiglia
    Luca Artiglia
    Laboratory of Environmental Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland
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    Orcidhttps://orcid.org/0000-0003-4683-6447
  • Fabrizio Orlando
    Fabrizio Orlando
    Laboratory of Environmental Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland
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  • Jacinta Edebeli
    Jacinta Edebeli
    Laboratory of Environmental Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland
    Institute of Atmospheric and Climate Sciences, ETH Zürich, 8006 Zürich, Switzerland
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  • Xiangrui Kong
    Xiangrui Kong
    Center for Atmospheric Research, University of Oulu, P.O. Box 4500, 90014 Oulu, Finland
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  • Huanyu Yang
    Huanyu Yang
    Laboratory of Environmental Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland
    Institute of Atmospheric and Climate Sciences, ETH Zürich, 8006 Zürich, Switzerland
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    Orcidhttps://orcid.org/0000-0002-0927-9621
  • Anthony Boucly
    Anthony Boucly
    Laboratory of Environmental Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland
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    Orcidhttps://orcid.org/0000-0003-1436-3462
  • Pablo Corral Arroyo
    Pablo Corral Arroyo
    Laboratory of Environmental Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland
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    Orcidhttps://orcid.org/0000-0003-4090-1623
  • Nønne Prisle
    Nønne Prisle
    Center for Atmospheric Research, University of Oulu, P.O. Box 4500, 90014 Oulu, Finland
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    Orcidhttps://orcid.org/0000-0002-2041-6105
  • Markus Ammann*
    Markus Ammann
    Laboratory of Environmental Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland
    *Email: [email protected]
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ACS Earth and Space Chemistry

Cite this: ACS Earth Space Chem. 2021, 5, 11, 3008–3021
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https://doi.org/10.1021/acsearthspacechem.1c00233
Published October 26, 2021

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Abstract

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The reaction of ozone with sea-salt derived bromide is relevant for marine boundary layer atmospheric chemistry. The oxidation of bromide by ozone is enhanced at aqueous interfaces. Ocean surface water and sea spray aerosol are enriched in organic compounds, which may also have a significant effect on this reaction at the interface. Here, we assess the surface propensity of cationic tetrabutylammonium at the aqueous liquid–vapor interface by liquid microjet X-ray photoelectron spectroscopy (XPS) and the effect of this surfactant on ozone uptake to aqueous bromide solutions. The results clearly indicate that the positively charged nitrogen group in tetrabutylammonium (TBA), along with its surface activity, leads to an enhanced interfacial concentration of both bromide and the bromide ozonide reaction intermediate. In parallel, off-line kinetic experiments for the same system demonstrate a strongly enhanced ozone loss rate in the presence of TBA, which is attributed to an enhanced surface reaction rate. We used liquid jet XPS to obtain detailed chemical composition information from the aqueous-solution–vapor interface of mixed aqueous solutions containing bromide or bromide and chloride with and without TBA surfactant. Core level spectra of Br 3d, C 1s, Cl 2p, N 1s, and O 1s were used for this comparison. A model was developed to account for the attenuation of photoelectrons by the carbon-rich layer established by the TBA surfactant. We observed that the interfacial density of bromide is increased by an order of magnitude in solutions with TBA. The salting-out of TBA in the presence of 0.55 M sodium chloride is apparent. The increased interfacial bromide density can be rationalized by the association constants for bromide and chloride to form ion-pairs with TBA. Still, the interfacial reactivity is not increasing simply proportionally with the increasing interfacial bromide concentration in response to the presence of TBA. The steady state concentration of the bromide ozonide intermediate increases by a smaller degree, and the lifetime of the intermediate is 1 order of magnitude longer in the presence of TBA. Thus, the influence of cationic surfactants on the reactivity of bromide depends on the details of the complex environment at the interface.

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SPECIAL ISSUE

This article is part of the Mario Molina Memorial special issue.

Introduction

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In atmospheric science, halogen chemistry and its impact on the ozone budget remains a hot topic. (1−3) The halide-solution–air interfaces associated with seawater and sea spray aerosol are especially important, because about 71% of the Earth’s surface is covered by seawater, which represents a substantial reservoir for chloride, bromide, and iodide. Multiphase reactions between gas-phase species and halides in seawater are centrally important, because they lead to activation of halogen species to the gas phase. (4,5) Cycling of these halogen species exerts a powerful influence on the chemical composition of the troposphere. It has been estimated that halogen chemistry contributes 50% of the chemical sink for tropospheric ozone globally. (6) It may affect the global oxidation capacity, the fate of pollutants and tropospheric ozone (including its radiative impact), and the production of particles. (4,5) Particle phase halogen species also contribute to ozone loss in the stratosphere. (7)
The multiphase oxidation of bromide (Br–) by O3 is a significant dark source of hypobromic acid (HOBr) when shorter-lived photochemically produced radicals and oxidants are not abundant. (6,8) These initial bromide oxidation processes are the starting point of the multiphase cycling reactions that lead to the release of bromine, thus bromine activation. Under the special circumstances of the spring-time polar marine boundary layer, bromine activation is a strong component of local and episodic O3 depletion. (9)
Ocean surface water and sea spray aerosol often contain complex mixtures of organics derived from marine biota with variable surface affinity and functionalities, such as proteins, carbohydrates, phospholipids, and fatty acids. (10−12) Surface active organics may affect multiphase chemical reactions by changing the interfacial activity of the halide ions or of reaction intermediates (13,14) or actively engage in chemistry and photochemistry. (15,16) Such effects have not been sufficiently elucidated, mostly because of the lack of studies selectively probing the interfacial region and processes thereon.
The kinetics of multiphase reactions initiated by gas phase oxidants are described by the uptake coefficient, γ, defined as the ratio of the net flux of molecules from the gas phase to the condensed phase divided by the gas-kinetic collision flux of the molecules to the surface of the condensed phase. (17) The multiphase reaction of O3 with Br– ions to HOBr has been studied for two decades and suggested to be enhanced at the aqueous solution–air interface. (18−26) In aqueous solution, Liu et al. (27) suggested that the mechanism involves a bromide ozonide as an intermediate (R1), which then decomposes into molecular oxygen (R2 and R3) and HOBr in an acid assisted step. HOBr then reacts further with Br–, again in an acid catalyzed reaction, to form Br2 (R4). Nevertheless, the reason for the surface enhanced reactivity had remained elusive.
(R1)
(R2)
(R3)
(R4)
The traditional approach to study the chemical composition at the aqueous solution–air interface through the contribution of constituents to the surface free energy is via recording the surface tension as a function of solute concentration. (28) However, this is not straightforward for complex solutions, because the synergistic effects and their composition dependence make it extremely difficult to assign concentration dependent contributions to the surface tension for individual components in solution. Both chemical composition and processes at interfaces can be characterized by X-ray photoelectron spectroscopy (XPS), which provides both chemical selectivity and surface sensitivity. (29) Liquid jet XPS directly provides the composition of inorganic and organic compounds at the aqueous solution–vapor interface within the topmost molecular layers of the liquid. (30−33) Using this technique, supporting theoretical calculation and additional kinetic experiments, Artiglia et al. (20) reported direct experimental evidence for the ozonide in R1 and found it to exhibit a high propensity for the liquid–vapor interface. This surface active intermediate turned out to be the cause of the surface enhanced reaction rate, rather than the debated abundance of bromide itself at the interface. (34)
In an attempt to address the impact of organics on the oxidation of bromide by O3, Lee et al. (35) recently studied the reaction of bromide with ozone in the presence and absence of citric acid, a proxy for highly functionalized organic compounds in the atmosphere, under ambient conditions. With citric acid, the uptake kinetics of O3 was faster than that predicted by bulk reaction-limited uptake and also faster than expected on the basis of an acid-catalyzed mechanism. Parallel liquid jet XPS revealed that bromide became depleted by around 30% within the probe depth of the experiment of around 1 nm. In 2019, Lee et al. (33) found an opposing effect of butanol and butyric acid on the abundance of bromide and iodide at the liquid–vapor interface. In comparison to the pure aqueous halide solution, 1-butanol increased the interfacial density of bromide by 25%, while butyric acid reduced it by 40%, respectively, which is probably controlled by a subtle interplay of electrostatic, dipole, and hydrogen bonding interactions. Therefore, looking at the effects of surfactant cosolutes with different properties is an important task for better constraining the interfacial reactivity of halides under environmental conditions.
Tetrabutylammonium (TBA) may be considered as a proxy for atmospherically relevant organic amines and other cationic surfactants derived from biogenic oceanic material. (12,36) Its amphiphilic character with aliphatic side chains makes it strongly surface-active in aqueous solution. On the basis of surface tension measurements, TBA bromide is expected to exhibit a surface excess of ∼3.0 × 1014 molecules per cm2 at 0.1 M. (13) TBA exhibits also a strong ion-pairing capacity, which makes TBA ions important in various areas of chemistry, e.g., in phase-transfer catalysis, where relatively hydrophobic cations are used for precipitating large anions. (37) Several studies have addressed the interfacial properties of TBA containing iodide solutions (including mixtures with bromide) with VUV photoemission. (38−41) Also molecular beam scattering experiments of N2O5 interacting with a liquid jet containing tetraalkylammonium surfactants indicated interactions between the positively charged surfactant and reactants or products, also depending on the solvent. (42,43) Overall, the details of how charged surfactant ions affect the halide ions, their reactivity, and potentially also reaction products have remained open.
In this work, we used liquid jet XPS to directly assess the impact of TBA on the abundance of bromide and the bromide ozonide at the aqueous solution–air interface and to compare the spectroscopic information with the results of O3 uptake kinetic experiments performed in parallel.

Experimental Section

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Materials

This study was conducted using sodium bromide (NaBr, Sigma-Aldrich, > 99.0%), sodium chloride (NaCl, Sigma-Aldrich, > 99.0%), and tetrabutylammonium bromide (TBA-Br, Sigma-Aldrich, > 99.0%) without further purification. Sample solutions were prepared by adding stock solutions to Milli-Q water (Millipore, 18.2 MΩ cm at 25 °C). NaBr (0.1 M), 0.1 M NaBr/0.55 M NaCl, 0.1 M TBA-Br, 0.1 M TBA-Br/0.55 M NaCl, and 0.1 M TBA-Br/0.1 M NaBr/0.55 M NaCl aqueous solutions were prepared for liquid jet XPS and kinetic experiments.

Liquid Microjet X-ray Photoelectron Spectroscopy (XPS)

XPS experiments using a liquid microjet were conducted at the Surfaces/Interfaces: Microscopy (SIM) beamline of the Swiss Light Source (SLS) (44) using the near ambient pressure photoemission (NAPP) endstation. (44,45) The electron analyzer uses a three-stage differentially pumped electrostatic lens system (Scienta HiPP-2) and a hemispherical analyzer (Scienta R4000) to collect photoelectrons from samples in chamber pressures up to a few millibar. For the present experiments, a quartz nozzle (MicroLiquids), forming a liquid microjet with a diameter of 25 μm, was used to deliver a liquid sample into the analysis chamber.
The liquid jet was operated with a flow rate of 0.5 mL/min. The capillary transporting the liquid was immersed in a cooling bath set to 277 K upstream of the feedthrough into the chamber. The characterization of aqueous solutions, without gas dosing, was performed in a vacuum (1.0 × 10–3–1.0 × 10–4 mbar). The diameter of the entrance orifice of the electron sampling aperture into the prelens and the working distance to the liquid jet were both 500 μm. The electron analyzer was operated at 20 eV pass energy (photoelectron kinetic energy at 155 eV) and 50 eV pass energy (photoelectron kinetic energy at 370 eV) with a 0.1 eV step size. The liquid filament position was adjusted to spatially overlap with the 100 μm (vertical) by 60 μm (horizontal) synchrotron light beam. (44) Optimum alignment was achieved by monitoring the condensed phase O 1s at 900 eV photon energy.
For experiments, in which the liquid jet was exposed to gas phase O3, we used a gas delivery system, which has been described in our previous work. (20) In brief, a second gas nozzle was fixed concentrically around the quartz nozzle delivering the liquid. The second gas nozzle reaches about 0.1 mm beyond the liquid jet nozzle. The gas starts to interact with the liquid wire from the end of the quartz nozzle delivering the liquid jet before expansion into the vacuum chamber at the end of the second nozzle. The admitted gas was either pure oxygen or a mixture of up to a few percents of ozone in oxygen. Before dosing the gas, the pressure in the experimental chamber was raised to 1 × 10–3 mbar (with the turbo molecular pump stopped and a SiNx window mounted between the X-ray beamline and the liquid jet chamber). While dosing the gas, the pressure was set to 0.25 mbar by means of a leak valve connected to the gas nozzle via a 1/16″ PEEK tube, leading to a gas flow rate of around 15 sccm/min. Ozone was generated online by means of a home-built corona discharge ozone generator. We varied the ozone concentration by changing the flow rate of O2 through the corona discharge unit in the range 2–12 mL/min. The corresponding change in the dilution ratio (around 1:7000) was taken into account for the ozone concentration calibration. The mixing ratio of O3 in O2 in the gas admitted to the experimental chamber was in the range 1%–3%. The efficiency of O2 to O3 conversion in the ozone generator was checked in separate experiments by means of the same ozone analyzer, as described further below for the kinetics experiments. The gas composition in the analysis chamber with respect to the major components N2, O2, H2O, and CO2 was checked by means of a quadrupole mass spectrometer installed in the second differential pumping stage of the electron analyzer.
Core level spectra of Br 3d, N 1s, C 1s, Cl 2p, and O 1s were acquired at photon energies allowing for photoelectron kinetic energies at 155 and 370 eV. Due to the high photon flux at the SIM beamline, using first order light to ionize the O 1s orbital of solutions would lead to potentially damaging count rates at the detector. We therefore made use of the around 10% of photon flux associated with second order light, which simultaneously passes the monochromator, to ionize the O 1s orbital. Thus, the monochromator was set to 348 and 450 eV to obtain O 1s spectra with excitation energies of 696 and 900 eV for KE values of 155 and 370 eV, respectively. Spectra were acquired by a sequence of sweeps over the regions of each element, and sequences were repeated until sufficient signal-to-noise ratios were obtained. Signal intensity ratios within one experiment thus take into account varying jet positions that would lead to intensity changes between sequences.
Reported binding energies are relative to the vacuum level and calibrated to the O 1b1 orbital of liquid water at 11.31 eV. (46) Exemplary valence spectra are shown in the Supporting Information (SI), Figure S1. The total photoionization cross section (σtot) was calculated by considering cross sections (σ) and asymmetry parameters (β) as follows: (47,48)
(1)
Core level spectra were fit using pure Gaussian functions following standard linear background subtraction, except for the Br 3d spectra related to the experiments with O3, where a Shirley background was subtracted. For C 1s, the full width at half-maximum (fwhm) of the peaks was constrained to the same value for the peaks contributed by the carbon atoms attached to the ammonium ion and by the butyl chain carbons. The spin–orbit split (SOS) for Br 3d was fixed at 1.03 eV for both bromide in pure NaBr solutions and the bromide ozonide also present when dosing O3. (20) We forced the fwhm at the same value for the spin–orbit split peaks of Br 3d (3d3/2, 3d5/2) of bromide and of Cl 2p (2p1/2, 2p3/2) of chloride, respectively, at 1.03 eV. The fwhm of the Br 3d peaks of bromide ozonide was 1.05 eV. The chemical shift between bromide and bromide ozonide was +0.70 eV. (20)

Flow Reactor

Kinetic experiments were conducted in a flow reactor setup previously described by Lee et al. (35) and Artiglia et al. (20) Briefly, the setup comprises a temperature regulated Teflon trough (surface area = 102 cm2) on which 15 mL of the reactive solution is loaded uniformly. The trough was kept at 4 °C for all experiments. Ozone was generated by 185 nm photolysis of O2 at different light intensities in a quartz cell at a flow rate of 400 mL/min O2 and then mixed with 2000 mL/min N2 (all flow rates given for 1 atm and 0 °C). Part of this gas flow (980 mL/min) was humidified to the saturation water vapor pressure at the temperature of the trough before admission to the trough. The gas flow was alternated between a bypass to measure the initial O3 concentration and the trough to measure the O3 concentration remaining after reactive uptake by the solution. The O3 concentration was measured using a commercial ozone monitor (Teledyne API model 400).
After about 1 h of stabilizing the background O3 concentration measured while the gas flow was bypassing the flow reactor, the gas flow was switched to the trough reactor, which led to exposure of the film to O3 allowing the multiphase reactions to take place. Finally, the concentration after the reactor was measured in bypass mode again to confirm that the background did not change during the experiment. The uptake coefficient of O3, γ, is equal to the rate of O3 loss to the aqueous phase divided by the gas kinetic collision rate (eq 2). The fractional loss of O3 was obtained from the average ozone concentration through the bypass ([O3]bypass) line measured before and after exposing the trough and that while the gas passed through the flow tube ([O3]flow tube) for each cycle. (35)
(2)
(3)
where φ is the flow rate of O3 through the flow tube (980 mL/min); ωO3 is the mean thermal velocity of O3 in the gaseous phase (cm/s); SA is the exposed internal surface area of the tube; and MO3 is the molecular weight of O3.
The average O3 uptake coefficient of the three cycles between the bypass and the flow tube per replicate was taken as the mean uptake coefficient for the experiment. We note that, for the low uptake rates observed in this work, gas phase diffusion was not limiting O3 loss, and the observed γ was used without further correction. The uptake coefficient was measured as a function of the partial pressure of O3 in the gas phase. This allows for disentangling the contributions by the bulk aqueous phase reaction in the reacto-diffusive regime and the surface reaction, (19,35) as described in more detail in the SI.

Results and Discussion

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Parts a and b of Figure 1 show O 1s and Br 3d photoelectron spectra, respectively, of 0.1 M NaBr, and 0.1 M TBA-Br aqueous solutions at photon energies of 900 eV (2nd order light) and 450 eV, respectively. The O 1s region in Figure 1a is fitted by two components that are assigned to gas phase water at ca. 541 eV binding energy and liquid water at ca. 539 eV binding energy. The chemical shift between O 1s of liquid and gas phase water is different for NaBr and TBA-Br solutions. This is also apparent in the valence spectra shown in Figure S1, which were used to align the binding energy scale with the O 1b1 level of liquid water. This shift may be due to different surface potentials, and a similar effect was observed for different solutions in our previous work. (33) The substantial photoemission intensity from gas phase water is related to the fact that the beam width of 60 μm is larger than the liquid filament diameter of 25 μm, so that photoelectrons from excitations in the gas phase surrounding the liquid are also collected. The Br 3d spectrum (Figure 1b) exhibits a double-peak structure due to spin–orbit splitting into 3d5/2 and 3d3/2. TBA-Br is expected to exhibit a surface excess of ∼3 × 1014 molecule per cm2 at 0.1 M. (13)

Figure 1

Figure 1. (a) O 1s and (b) Br 3d photoelectron spectra of 0.1 M TBA-Br and 0.1 M NaBr aqueous solutions at photon energies of 900 and 450 eV, respectively. (c) O 1s and (d) Br 3d photoelectron spectra of 0.1 M TBA-Br and 0.1 M NaBr aqueous solutions in the presence of O3, at photon energies of 900 and 450 eV, respectively. The spectra within each panel share the y-axis scale.

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It becomes already apparent from the spectra shown in Figure 1b that the Br 3d signal intensity, when referenced to the condensed O 1s signal, is substantially larger in TBA bromide solutions than in pure NaBr solutions. This is likely related to the positive surface excess of TBA and to either ion pairing or longer range electrostatic interaction with the positively charged TBA. This way more Br– ions are attracted into the liquid–vapor interface than in the neat NaBr solution with the same bromide bulk concentration. The surface activity of TBA, resulting in a carbon-rich layer at the interface, leads to attenuation of both Br 3d and O 1s photoemission signals, which is directly apparent for the O 1s signal of liquid water and will be quantitatively analyzed together with the C 1s spectra further below. Note that the y-axis in terms of the count-rate is the same for the spectra within each panel; however, the intensity may also vary due to changes in the jet position from experiment to experiment. Therefore, it is not clear whether the different gas phase signals in Figure 1a indicate an effect of TBA on the evaporation of H2O from the liquid.
The same O 1s (Figure 1c) and Br 3d (Figure 1d) spectra were taken in the presence of O3/O2 to probe the bromide ozonide (intermediate in the reaction to hypobromite) at the same information depth. The relatively larger contribution of gas phase water compared to the experiments without gas dosing is due to the presence of gas phase oxygen (0.25 mbar), which leads to a higher local water vapor concentration around the liquid filament due to diffusion limitation. The higher pressure also leads to more attenuation of the O 1s signal from condensed phase water. Note that the O 1s peak related to gas phase oxygen is at a binding energy about 7 eV higher than that of gas phase water (see Figure S2), thus outside the binding energy range shown in Figure 1c.
In Figure 1d, both Br species show two spin orbit split doublets, which are assigned to Br– and the [Br·OOO]− intermediate. The doublet assigned to the [Br·OOO]− intermediate is positively shifted by 0.7 eV with respect to Br–, in line with the previous study by Artiglia et al., (20) which also provides a more detailed explanation for the fitting procedure. In support of the presence of this second Br species, we added the spectra of Figure 1d to Figure S2, using a fit with just one bromine species, bromide, but using width and spin–orbit split constrained by the measurement in absence of O3. The residuals clearly show the need to add this second species to properly fit the spectra. In a vacuum, the Br 3d signal intensity was clearly larger in TBA bromide containing solutions than that in pure NaBr solutions. In the presence of O2/O3, the ratio between the two is even larger. Note that even though the ratio of the signal intensity contributed by the [Br·OOO]− intermediate to that contributed by the Br– species is rather similar in the presence and absence of TBA-Br, at 0.21 ± 0.04 and 0.15 ± 0.03, respectively, the concentration and stability of the intermediate are clearly different in the presence of TBA, as discussed in detail in the second part.
In parallel, we performed kinetic experiments of the reactivity of O3 with the same solutions. The uptake kinetics is expressed by the uptake coefficient, representing the rate of O3 loss from the gas phase normalized to the gas-kinetic collision rate, defined in eq 2. Figure 2a shows the measured and parametrized uptake coefficients of O3 as a function of gas phase O3 concentration for aqueous solutions containing 0.1 M NaBr (black), 0.1 M NaBr/0.55 M NaCl (gray), 0.1 M TBA-Br (red), and 0.1 M TBA-Br/0.55 M NaCl (dark-blue), which directly demonstrate the obvious enhancement of reactivity for the TBA containing solutions at low O3 mixing ratios. Lines are fits with a kinetic model consisting of a combination of a Langmuir–Hinshelwood type surface reaction and a reaction-diffusion mechanism in the bulk phase based on our previous study (20) and as described in the Supporting Information, Section VIII. At high ozone concentrations (above 200 ppb), the uptake coefficients are constant, whereas the uptake coefficients are increasing toward the lower atmospherically relevant ozone mixing ratios (between 100 and 30 ppb). In previous studies, (19,20) this behavior has been attributed to a surface reaction dominating at a low ozone concentration. It results from the fact that the surface coverage of O3 is saturating at a higher concentration, which leads to the surface reaction rate saturating with a higher ozone concentration, as described by eq S21 in the SI. In contrast, the bulk phase concentration of O3 scales linearly with the gas phase partial pressure (Henry’s law) in the relevant concentration range, which leads to the bulk reaction rate remaining independent of the ozone concentration in the gas phase (eq S22 in the SI). In a recent study with a similar reactor of comparable geometry, it has been suggested that liquid phase diffusion may limit the uptake coefficient. (49) As also explained in the SI, the bulk diffusion limitation of bromide can be excluded under the present conditions. The measured ozone uptake coefficients in the absence of TBA are consistent with previous studies from our group (20) and the work by Oldridge and Abbatt. (19) The small difference between the pure NaBr and the mixed NaBr/NaCl solutions at a high ozone concentration is explained by the 10% lower solubility of O3 due to salting out by the 0.55 M NaCl and the small difference in diffusivity caused by a small change in viscosity. Both are included in the parametrization for the uptake coefficient (see the Supporting Information, section VIII). In the presence of TBA, the ozone uptake coefficient is higher than those on the pure NaBr and NaBr/NaCl mixed solutions at low ozone concentrations, whereas they tend to be similar to the systems without TBA at higher ozone concentrations, indicating that the surface reaction contribution is more strongly affected by the presence of TBA than the bulk reaction. The rather small difference between ozone uptake in solutions with and without TBA at a high ozone concentration could be explained by 11.5% larger viscosity and 1.5% larger solubility of O3 in TBA-Br solutions compared with those of pure NaBr. In the presence of TBA, the effect of 0.55 M NaCl is also seen, especially at a high ozone concentration, which is due to both the higher viscosity (11.5% higher) and the lower solubility of O3 (7.8% lower) compared with those of pure NaBr. For the bulk reaction, the parametrization for the uptake coefficient is based solely on known parameters (solubility, rate coefficient, diffusivity) without any additional adjustable parameters. For the loss rate on the surface, as described in the Supporting Information (section VIII), the essential parameters are the equilibrium constant for the formation of the intermediate (KLang in eq S21), the maximum surface coverage of the intermediate (Nmax), and the first-order decay rate coefficient (ks) for the formation of the product BrO–. Whereas the value for KLang was taken from Artiglia et al., (20) which was also consistent with Oldridge and Abbatt, (19) the maximum surface coverage was constrained by the XPS data (as described further below), and the rate coefficient was the only adjustable parameter used to fit the data, leading to very good fits for each solution, as shown in Figure 2a.

Figure 2

Figure 2. (a)nMeasured and parametrized uptake coefficients of O3 as a function of gas phase O3 concentration for 0.1 M NaBr (black), 0.1 M NaBr/0.55 M NaCl (gray), 0.1 M TBA-Br (red), and 0.1 M TBA-Br/0.55 M NaCl (dark-blue) in the aqueous solutions. (b) Uptake coefficient of O3 at 36 ppb compared with the measured [Br·OOO]−/O intensity ratio for three different aqueous solutions.

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The strikingly parallel behavior of the enhancement of the surface contribution of the uptake coefficient in the presence of TBA and that of the increased presence of both bromide and the reaction intermediate, as determined by XPS, supports the hypothesis that the positively charged ammonium group in TBA helps to attract Br– ions to the interface and establishes an enhanced surface concentration of the [Br·OOO]− intermediate limiting the reaction rate. Sobyra et al. (42) studied the production of Br2 from the reaction of N2O5 with Br– in TBA-Br solutions. They found a reduction of Br2 formation in the presence of TBA and attributed that to ion-pairing of TBA+ with Br3– at the liquid–vapor interface. Since our experiments are not sensitive to the products, neither in the kinetics nor in the spectroscopy experiment, we cannot assess the fate of BrO– in our case. Similarly, a possibly enhanced loss rate of N2O5 to a bromide enriched interface would have remained undetected in the experiments by Sobyra et al. To make the rate-limiting role of the [Br·OOO]− intermediate directly apparent, Figure 2b shows the linear correlation between the uptake coefficient of O3 at 36 ppb and the measured ratio of the Br 3d photoemission intensity from the [Br·OOO]− intermediate to the O 1s intensity of liquid water for three different aqueous solutions. Note that it was not possible to reliably fit the Br 3d spectrum in terms of the intermediate in the case of the mixed solution of 0.1 M TBA-Br and 0.55 M NaCl. Note that, in the XPS experiment, we cannot quantify the local O3 pressure near the liquid surface but assume that it is higher than in the kinetic experiments. This leads to saturating surface concentrations of the intermediate. In the kinetic experiments, at such a high concentration, the bulk reaction is dominating the loss of O3, even though the loss rate at the surface remains the same as at the lowest partial pressures of O3. As already discussed in Artiglia et al., (34) the BrO– product produced in the bulk or at the surface is not detected by XPS due to fast diffusional exchange in the liquid phase beyond the probe depth of XPS.
In an attempt to link the enhanced reactivity more quantitatively to the local interfacial concentration of bromide, we developed an attenuation model to account for the attenuation of photoelectrons by the “layer” formed by the aliphatic carbon chains of the TBA surfactant that are residing at the interface (Figure 3). This model is then constrained by the available photoemission data. The attenuation model used in the present work is following the one developed by Lee et al. (33) Its setup, depicted in Figure 3, assumes that the interfacial region contains TBA, the concentration of which is constrained by surface tension measurements. In more detail, we assume that the cationic N and its surrounding C atoms reside on the bulk side of the interface, with three of the remaining aliphatic chains above it, within a layer of thickness d1, and one aliphatic chain pointing toward the bulk, extending to a depth d2, inspired by molecular dynamics simulations presented by Winter et al. (39) for TBA iodide. We further consider a region of thickness Δ within which the bromide concentration differs from that in the bulk aqueous phase, as in Lee et al. (33) Its thickness Δ is independent of whether TBA is present or not. The details of the attenuation model and the derivation of the equations describing the photoemission signals are provided in the Supporting Information (Section VI). These equations fully account for the exponentially decaying contribution of photoelectrons from atoms with depth below the surface. For each element, these contributions are integrated over the density profiles as described above. Since the structure of the bromide ozonide intermediate at the TBA covered interface is not clear and its coverage on the surface remains small, we refrain from applying the model in any way to the Br 3d photoemission intensities of the intermediate.

Figure 3

Figure 3. Scheme of the TBA covered interface used for the attenuation model. The reference level 0 for the depth scale (z) denotes the position where the water density drops to zero and is put just above the N-group of TBA, such that the aliphatic carbons of three of the butyl chains reside at – d1 < z < 0 (on the vacuum side). The aliphatic carbons of the fourth chain are within z < d2. The layer 0 < z < Δ is representing the layer in which the concentration of bromide is deviating from its bulk value, nb,Br, by the factor f. Red, blue, and dark and light gray spheres denote bromide, nitrogen, carbon, and hydrogen atoms, respectively.

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We first used the C 1s photoemission data shown in Figure S4 to constrain the thickness, d1, of the top layer (-d1 < z < 0), which is the basis for the attenuation of all photoemission signals originating from the bulk. As shown in Figure 4a, the aliphatic group C 1s photoemission intensity for the TBA-Br solutions measured at 660 eV photon energy as a function of the concentration from 0.01 to 0.2 M (see individual spectra in the Supporting Information, Section IV and Figure S4), which essentially tracks the evolution of the surface excess as derived from surface tension data (Supporting Information, Section VII and Figures S6 and S7). (13)

Figure 4

Figure 4. (a) Normalized methyl carbon C 1s and (b) liquid water O 1s photoemission intensity as a function of TBA-Br concentration for four different TBA-Br concentrations, measured at photon energies of 660 and 900 eV, respectively. (c) Normalized C/O intensity ratio as a function of TBA-Br concentration from the data in (a) and (b). Normalization as described in the text. Symbols present the experimental data, and the lines are the calculated quantities returned by the attenuation model described in the text.

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Meanwhile, the correlation between C 1s photoemission intensity and the surface excess has been demonstrated for many surface active organic species. (32,33,50−53) The surface excess formed the basis for the retrieval of the effective thickness of the layer formed by the aliphatic carbons from the calculated C 1s signal fitted to the data (eq S6). The purpose was to replace detailed electron scattering calculations by assuming a homogeneous layer consisting of liquid butane, for which we could approximate the inelastic mean free path by that of liquid water (see the Supporting Information, Section VII). In Figure 4b, we show the concomitant decrease of the condensed phase O 1s signal of H2O. We note that the decrease is less pronounced than expected from the attenuation of photoelectrons by the increasing effective thickness of the aliphatic carbon layer as calculated by the model (eq S7), possibly because water molecules hydrating the central cation are filling a larger fraction of the carbon chain than assumed in the model. The ratio of the two signals is shown in Figure 4c exhibiting the typical feature for surfactant behavior. (29,51) Note that the calculated lines were scaled with a factor, since the absolute detection efficiency is not known. For the ratio in Figure 4c, this provides the calibration factor for the C 1s to O 1s photoemission intensity ratio, A/B, in eq S10. The calculated effective layer thickness, d1, as a function of the TBA bulk concentration led to good agreement with the data. This thickness was then used for the quantitative analysis of the bromine signals further below. Apart from providing surface composition data, the ratio of photoemission intensities contributed by the aliphatic carbons to that by the amine coupled carbons contains information about the orientation of the surfactants. (31,51,54) For simple monocarboxylic acids, the headgroup is solvated while the aliphatic chains are residing above the surface. Therefore, photoelectrons from the aliphatic carbons are less attenuated than those from the headgroup carbon, leading to enhanced photoemission signal intensity ratios. However, in the case of TBA, this effect is rather weak (Figure S5), because only one of the butyl chains is pointing upward, while two are lying flat on the surface and one is pointing into the solution, (38) as schematically depicted in Figure 3. In the bulk phase, the complete hydration of TBA with around 20 water molecules as well as counterions between the hydrocarbon arms of TBA was derived from molecular dynamics simulations. (55) No aggregation was apparent. At the surface, our results of the C/O intensity ratio indicate that at least part of the aliphatic carbon chains is not hydrated. This might be part of the driving force for residing at the surface. In addition, the large polarizability and size of TBA ions also contribute to their surface propensity. (38)
Figure 5 shows the photoemission spectra of the Br 3d (a), O 1s (b), C 1s (c), N 1s (d), and Cl 2p (e) core level regions for 0.1 M TBA-Br (red), 0.1 M TBA-Br/0.55 M NaCl (dark blue), 0.1 M TBA-Br/0.1 M NaBr (pink), and 0.1 M TBA-Br/0.1 M NaBr/0.55 M NaCl (light blue) aqueous solutions. We used photon energies of 229 eV for Br 3d, 696 eV for O 1s (2nd order light component of the 348 eV photon energy adjusted at the monochromator), 448 eV for C 1s, and 560 eV for N 1s to obtain the same kinetic energy of around 155 eV. Thus, the data in Figure 5 was obtained at a smaller kinetic energy than those in Figure 1 to achieve a higher surface sensitivity. We measured the [Br·OOO]− intermediate at a kinetic energy of 370 eV to have better signal-to-noise ratio for quantitative analysis and for comparison with our previous work. (20) The shapes of O 1s and Br 3d have already been discussed above in relation to Figure 1. The lower kinetic energy leads to a higher ratio of gas phase to condensed phase water signal for the O 1s level. C 1s (Figure 5c) exhibits, as also seen in Figure S4, two features representing aliphatic chain carbon (−C3H7) and the ammonium coupled carbon (−CH2–N) at binding energies of 290.6 and 291.9 eV, respectively. The N 1s spectrum (Figure 5d) shows a single peak at a binding energy of 408.0 eV.

Figure 5

Figure 5. (a) Br 3d, (b) O 1s, (c) C 1s, (d) N 1s, and (e) Cl 2p photoemission spectra of aqueous solutions taken at a kinetic energy of 155 eV for 0.1 M TBA-Br (red), 0.1 M TBA-Br/0.55 M NaCl (dark blue), 0.1 M TBA-Br/0.1 M NaBr (pink), and 0.1 M TBA-Br/0.1 M NaBr/0.55 M NaCl (light blue), normalized to the the number of sweeps. Lines with symbols represent the measured data, and the shaded areas represent the fitted contributions of the corresponding core levels.

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The first step toward the quantification of the surface composition is to consider the signal intensity ratioed to that of O 1s, since then several uncertainty factors, such as the transmission function of the analyzer, or a variable jet position are canceling out. Table 1 summarizes the ratios of Br 3d, C 1s, N 1s, and Cl 2p intensities to that of O 1s. Each signal intensity has also been normalized to the total photoionization cross section and photon flux. Since for the O 1s measurement we used second order light, for which we have not quantified the photon flux precisely, these ratios are not absolute elemental ratios but should be considered relative with respect to the different solutions. For the C 1s to O 1s signal intensity ratio, we note that, on the basis of the calibration factor obtained from fitting the TBA concentration dependent data (Figure 4), we can use the TBA-Br solution with its known surface excess to derive the TBA surface excess of the other solutions, as C 1s signal intensity ratios scale linearly with the surface excess for different solutions. (33,51,53)
Table 1. Ratios of Normalized Photoemission Signal Intensity of Br 3d, C 1s, N 1s, and Cl 2p to that of O 1s of Liquid H2O, Calculated Interfacial Concentrations of Bromide, Their Driving Parameters as well as the First Order Loss Rate Coefficient of the Intermediate, ksa
solutionBr/O–CH2–N/O–C3H7/ON/OCl/OΓTBA [1013 cm–2]fanBr,Δ [M]nBr,ΔΔ [1013 cm–2]ks [10–3 s–1]
0.1 M NaBr0.06     0.5 0.050.304.5
0.1 M TBA-Br0.751.244.030.18 29.69.917.00.995.960.43
0.1 M TBA-Br/0.1 M NaBr0.951.063.540.14 28.0b15.827.81.609.63 
0.1 M NaBr/0.55 M NaCl0.24   0.13 3.0 0.301.810.38
0.1 M TBA-Br/0.55 M NaCl0.341.435.40.450.3433.2b4.30.420.432.590.94
0.1 M TBA-Br/0.1 M NaBr/0.55 M NaCl0.561.986.40.530.2535.4b9.01.90.905.42 
a

The error associated with the individual photoemission signal intensities is estimated at around ±10%, which considers uncertainties due to the variability of the liquid jet XPS experiment, the solution preparation, and spectral fitting. Propagation leads to around 15% for elemental ratios and around 20% for the concentrations given. This does not include systematic errors related to the choice of the value for Δ or other inherent assumptions of the attenuation model.

b

Calculated on the basis of calibration of C/O signal intensity ratio with the TBA-Br solution.

Qualitatively, and in extension to the data presented in Figure 1, the Br spectra in Figure 5 and Br/O ratios presented in the first column of Table 1 show the dramatic enhancement of the Br signal in the presence of TBA, as well as a partial suppression of this enhancement by 0.5 M NaCl. In addition, salting out of bromide to the surface by NaCl is apparent in absence of TBA. Furthermore, the C 1s and N 1s data in Figure 5 and Table 1 indicate a salting out of TBA in the presence of NaCl, meaning that more TBA is pushed to the interface in the presence of NaCl. These features will be discussed one by one below.
For a quantitative interpretation of the Br data and its link with the reactivity discussed above, we have used the observed Br/O signal intensity ratios to obtain the interfacial concentration of bromide, nBr,Δ, within the layer of thickness Δ (see the conceptual model of the interface, Figure 3). This is described by the factor, f, representing the enhancement (f > 1) or depletion (f < 1) in comparison to the bromide concentration in the bulk, nBr,b (Figure 3), nBr,Δ = fnBr,b. The results are listed in Table 1 both in terms of nBr,Δ in units of M and as effective surface coverage, nBr,ΔΔ, in units of molecules cm–2. For the pure NaBr solution, we used the same approach as in Lee et al. (33) to link the Br/O signal intensity ratio to the surface excess (Supporting Information, Section VI, eqs S11 and S14). Note that the choice of Δ = 1 nm is somewhat arbitrary. But, this depth seems reasonable to represent the interfacial region in view of a number of molecular dynamics simulations on such systems. (34,38,39,42) We note that all other surface concentrations discussed below are depending on this choice, leading to systematic uncertainty. f0 = 0.5 (for pure 0.1 M NaBr) was obtained from the surface excess of −3 × 1012 molecules per cm–2 (eq S11), which is consistent with surface tension data at 0.1 M concentration. (56) This means that, within this surface layer, the average concentration of bromide is about 50% of its bulk value, thus 0.05 M or an effective surface concentration of 3 × 1012 ions cm–2 (see Table 1). The depleted character at the surface of halide solutions is thus in agreement with surface tension data and also other liquid jet photoemission studies and the most recent molecular dynamics simulations with revised force fields. (34,57,58)
In the presence of TBA, the deviation of f from f0 is described as a linear function of the surface coverage of TBA, with the parameter a describing the maximum enhancement at saturating coverage (SI, eq S13). The parameter f was obtained from eq S13 and using the calibration factor for the Br/O signal intensity ratio determined from the pure NaBr solution (Supporting Information, eq S15). Using f, we obtained the interfacial bromide concentration, which is enhanced by a factor of 20 in comparison to that of the pure NaBr solution. This takes into account the attenuation by TBA on the surface, which leads nearly to a doubling of the relative enhancement in comparison to that apparent from the Br 3d signal. This enhancement is likely due to electrostatic interactions between bromide and the positively charged TBA, including the formation of ion pairs. Such interactions have been found earlier for other surfactant systems (30) and specifically also for solutions containing TBA iodide. (38,39,59−61) Using He backscattering, Zhao et al. (62) determined that bromide is distributed within a width of around one nanometer at the interface for tetrahexylammonium (THA) bromide in glycerol as a solvent. Note that this is compatible with our choice of Δ used to calculate local concentrations. In turn, the probe depth of our experiment, typically defined as three times the mean escape depth (around 1 nm, see the Supporting Information, Section VI for details), is larger. Nevertheless, while 95% of the signal originates from around 3 nm, still about 80% comes from the first nanometer. However, all of this is embodied in the integrations to calculate the signal intensities on the basis of the attenuation model. The TBA surface coverage given in the table for TBA-Br is the same as that used for the fits in Figure 4 and is based on surface tension measurements at 0.1 M. (13) In turn, the effective surface coverage of bromide is a factor of 5 lower, meaning that not all TBA ions have formed pairs with bromide. Bhowmik et al. (55) suggested that, in solutions with higher bulk concentrations, bromide resides in the spaces between the butyl chains in fully hydrated form. Therefore, even if at the interface part of these chains are avoiding the aqueous phase, there would be sufficient room for equimolar amounts of bromide to approach the cations. Also, on the basis of the C/O and Br/O ratios and the concentrations derived, the substantial amounts of water (52,63) (in terms of mole fraction) at the interface should not be a limiting factor for bromide approaching the interfacial region. The question remains whether OH– is competing with bromide or whether neutral TBAOH (TBA hydroxide) is stabilized at the interface. In the presence of additional 0.1 M NaBr, thus doubling the amount of bromide in the bulk, the interfacial bromide concentration increases by 60%, thus less than a factor of 2. This nonlinear response to additional bromide is also consistent with the presence of such competing processes. Note that, in the calculation of the surface concentrations from recorded XPS intensities, the contribution by the increasing bulk concentration is taken into account (Supporting Information, eq S12), although it remains very small due to the predominant contribution of bromide at the interface. The surface excess of TBA, calculated by linear scaling on the basis of the C/O ratios and using the 0.1 M TBA-Br solution as reference, did not change significantly in the presence of additional 0.1 M NaBr added to TBA-Br (the calculated value is actually below that of TBA-Br but is considered remaining within the error bounds of the 0.1 M TBA-Br solution).
When 0.55 M NaCl (representing roughly ocean water chloride concentration) is present together with 0.1 M NaBr, but in absence of TBA, the interfacial concentration of Br– calculated from the Br/O photoemission intensity ratio is 0.30 M, which is a factor of 6 higher than in the case of the pure NaBr solution. This apparent salting out of bromide, or, in other words, enhanced Br/Cl ratio at the interface due to the higher polarizability of bromide versus that of chloride, has been reported and discussed before. (64) Exploring it further was not the scope of the present study.
In the presence of both NaCl and TBA bromide, several effects come together. Apart from the higher surface propensity of bromide in the presence of chloride, TBA experiences salting out, too, and chloride may compete with bromide for ion-pairing with TBA at the interface. Taking the calibration for the aliphatic C 1s to water O 1s photoemission ratio for the TBA-Br solution, the 20% increase of the C/O ratio leads to a surface excess of 3.3 × 1014 cm–2 of TBA in the presence of 0.55 M NaCl, thus an increase by about 10% compared to the 0.1 M TBA-Br solution. Salting effects of organics in the presence of inorganic electrolytes, with salting out being the more common case, are a well-described phenomenon, but predictive tools remain poorly constrained. (65,66) Salting out has been substantiated also by XPS for butanol in the presence of iodide (67) or by scattering for THA bromide in the presence of 0.3 M NaBr. (62) In the latter case, though in glycerol, a widening of the depth profile of THA has been observed, possibly beyond the thickness of a monolayer. In the present work, the photoemission signals of the carbons directly attached at the amine nitrogen changed in accordance with the aliphatic carbons, meaning that no substantial change in average orientation is apparent. On the contrary, the N 1s to O 1s signal intensity ratio changed by more than a factor of 2. It could indicate that the amine group of a fraction of the TBA ions has moved toward the vacuum side of the interface, which would also point toward a more complex structure than the simple ideal monolayer assumed in our attenuation model. More detailed kinetic energy dependent XPS experiments would be required to explore this further. The analysis of the Br/O ratios and the estimation of the interfacial bromide concentration within 0 < z < Δ would not be affected by such a potentially thicker overlayer at z < 0, as Br and O photoemission signals would experience the same degree of attenuation.
While the amount of TBA at the surface increases in the presence of chloride, a 3-fold decrease of the Br/O signal intensity ratio was observed, corresponding to a decrease of the interfacial concentration within 0 < z < Δ by about 60% in comparison to that of the 0.1 M TBA-Br solution in the absence of NaCl. The decrease in the bromide concentration can be rationalized by the competition between Cl– and Br– for ion-pairing with TBA. The association constant of TBA with Br– is about 1 order of magnitude higher than that with Cl–. (68) This explains why in spite of a factor of 5 excess of Cl– still 40% of the Br– concentration determined for the case of 0.1 M TBA-Br remains at the interface. A similar difference in association constants for Br– and Cl– exists with NH4+. (69) For alkylammonium cations, the association constants decrease with anion size and polarizability, e.g., for the pairs of TBA-I and TBA-ClO4 (70) or for TBA-I and TBA-Br. (71) For the latter pair, Winter et al. (39) found only a small decrease of the iodine photoemission signal when adding NaBr to TBA-I, comparable to our observations. When looking at the chlorine signal in our experiments, the Cl/O ratio (see Table 1) increased by nearly a factor of 3 from the 0.1 M NaBr/0.55 M NaCl solution to that with 0.1 M TBA-Br/0.55 M NaCl. In turn, when adding another 0.1 M NaBr, the Cl/O ratio again decreases by about one-third due to the more competitive association of Br– with TBA. For the latter solution, the interfacial Br– concentration reaches nearly 60% (0.9 M) of the corresponding solution without NaCl (1.6 M).
In Figure 2b, we observed a clear correlation between the uptake coefficient of O3 with the photoemission signal from the bromide ozonide intermediate. With the estimated interfacial bromide concentrations, we can assess the relationship between the uptake coefficient at 36 ppb (where it is dominated by the surface reaction) and the interfacial bromide concentration (Figure 6). In the absence of NaCl, the uptake coefficient, thus the overall turnover of O3 at the surface, increases by about 60%. This is paralleled by a 20-fold increase of the interfacial bromide concentration (red dotted arrow in Figure 6). In turn only a 3-fold increase of the intermediate signal (Figure 2b) was observed. Even if taking into account a similar ratio between signal and concentration as for bromide, the steady state concentration of the intermediate increases by much less than that of bromide itself but still considerably more than the uptake coefficient. Therefore, limitations seem to be at work that prevent interfacial bromide from being more efficiently reacted in the presence of TBA. This could be related to limitations imposed by the high density of alkyl chains at the interface. However, a previous study has shown that even strongly ordered monolayers of fatty acids have permeabilities sufficiently large to allow uptake coefficients of O3 2 orders of magnitude larger than in the present work. (72) Therefore, it is more likely that the stability of TBA-Br ion pairs lowers the reactivity with O3 to form the bromide ozonide intermediate. In addition, on the basis of the first order rate coefficients of the intermediate, ks (last column of Table 1), which were retrieved from the fits to the kinetic data, the presence of TBA affects the lifetime of the intermediate by about 1 order of magnitude when comparing 0.1 M NaBr and 0.1 M TBA-Br. In the presence of NaCl, but in the absence of TBA, in spite of the substantially increased interfacial bromide concentration, the uptake coefficient is 60% lower than that for pure NaBr, which is more in line with the reduced abundance of the intermediate. Thus, even for this inorganic mixture, the abundances of bromide and of the bromide ozonide intermediate are not in accord with each other, which justifies further work. In the presence of TBA and NaCl combined, the uptake coefficient of O3 was nearly as high as that in the absence of NaCl, even though the interfacial bromide concentration was almost 60% lower. This again indicates that the interfacial abundance of bromide is not the sole indicator for reactivity but rather that the details of how O3 may accommodate to the surface in the presence of TBA and the way the ozonide intermediate may be stabilized are important.

Figure 6

Figure 6. Uptake coefficient of O3 at 36 ppb compared with the measured Br–/O intensity ratio (lower x-axis, green) and calculated Br– interfacial concentration (upper x-axis, pink) for four different aqueous solutions.

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Conclusion

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In this study, we measured the surface propensity of cationic tetrabutylammonium at the aqueous liquid–vapor interface by liquid microjet X-ray photoelectron spectroscopy and the effect of this surfactant on ozone uptake to aqueous bromide solutions. The positively charged nitrogen group in TBA, along with its surface activity, is leading to enhanced interfacial concentration of bromide and the [Br·OOO]– intermediate due to electrostatic interactions. In parallel, in kinetic experiments for the same system, a strongly enhanced ozone loss rate in the presence of TBA on the surface of bromide solutions was observed. An attenuation model was developed to account for the attenuation of photoelectrons by the carbon-rich layer of the TBA surfactant. The more quantitative analysis demonstrates that TBA-Br increases the local density of bromide ions by a factor of 20 above that of neat aqueous bromide solutions at the same bulk concentration. Similarly, mixing TBA-Br with NaCl at seawater concentration led to an interfacial bromide ion density enhanced by about 43% compared to the corresponding mixture of just NaBr and NaCl. Still, the reaction rates of O3 with these solutions were not simply proportional to the interfacial bromide concentrations, as other effects, such as the different interfacial structure, or the stabilization of the reaction intermediate are additional factors influencing reactivity.
Aliphatic amines and amino acids are important positively charged surfactants at the sea surface microlayer (the topmost organic-rich layer), with average concentrations in the range 50–1500 ng L–1. (12,36,73) This work shows that they may exert strong effects on halogen activation processes and their presence should be considered when it comes to assess the impact of halogen chemistry on the atmospheric oxidation capacity and the climate.

Supporting Information

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The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acsearthspacechem.1c00233.

  • Figures of valence spectra, O 1s and Br 3d photoelectron spectra, O 1s and C 1s photoemission spectra, ratio of C1s photoemission intensity of aliphatic carbon to that of amine coupled carbon, measured surface tension, and surface excess of TBA-Br, discussions of calculation of photoemission signal intensity ratios based on the attenuation model, surface excess of TBA-Br derived from surface tension measurements, and calculation of the uptake coefficient (PDF)

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Author Information

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  • Corresponding Author
  • Authors
    • Shuzhen Chen - Laboratory of Environmental Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland;  Institute of Atmospheric and Climate Sciences, ETH Zürich, 8006 Zürich, Switzerland
    • Luca Artiglia - Laboratory of Environmental Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland;  Orcidhttps://orcid.org/0000-0003-4683-6447
    • Fabrizio Orlando - Laboratory of Environmental Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland;  Present Address: Omya International AG, Baslerstrasse 42, CH-4665 Oftringen, Switzerland
    • Jacinta Edebeli - Laboratory of Environmental Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland;  Institute of Atmospheric and Climate Sciences, ETH Zürich, 8006 Zürich, Switzerland
    • Xiangrui Kong - Center for Atmospheric Research, University of Oulu, P.O. Box 4500, 90014 Oulu, Finland;  Present Address: Department of Chemistry and Molecular Biology, University of Gothenburg, 41296 Göteborg, Sweden
    • Huanyu Yang - Laboratory of Environmental Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland;  Institute of Atmospheric and Climate Sciences, ETH Zürich, 8006 Zürich, Switzerland;  Orcidhttps://orcid.org/0000-0002-0927-9621
    • Anthony Boucly - Laboratory of Environmental Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland;  Orcidhttps://orcid.org/0000-0003-1436-3462
    • Pablo Corral Arroyo - Laboratory of Environmental Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland;  Present Address: Department of Chemistry and Applied Biosciences, Laboratory of Physical Chemistry, ETH Zurich, Vladimir-Prelog-Weg 2, Zurich 8093, Switzerland;  Orcidhttps://orcid.org/0000-0003-4090-1623
    • Nønne Prisle - Center for Atmospheric Research, University of Oulu, P.O. Box 4500, 90014 Oulu, Finland;  Orcidhttps://orcid.org/0000-0002-2041-6105
  • Author Contributions

    The manuscript was written through contributions of all authors. All authors have given approval to the final version of the manuscript.

  • Funding

    This project was supported by the Swiss National Science Foundation (grant no 169176). This project received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program, Project SURFACE (grant agreement no. 717022). N.P. also gratefully acknowledges the financial contribution from the Academy of Finland, including grant nos. 308238, 314175, and 335649.

  • Notes
    The authors declare no competing financial interest.

Acknowledgments

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This work was performed at the SIM beamline of the Swiss Light Source, Paul Scherrer Institute, Villigen PSI, Switzerland. The authors would like to thank Dr. Xing Wang from University of Bern for helpful discussions on the attenuation modelling.

References

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    Halogen chemistry reduces tropospheric O3 radiative forcing
    Sherwen, Tomas; Evans, Mat J.; Carpenter, Lucy J.; Schmidt, Johan A.; Mickley, Loretta J.
    Atmospheric Chemistry and Physics (2017), 17 (2), 1557-1569CODEN: ACPTCE; ISSN:1680-7324. (Copernicus Publications)
    Tropospheric ozone (O3) is a global warming gas, but the lack of a firm observational record since the preindustrial period means that ests. of its radiative forcing (RFTO3) rely on model calcns. Recent observational evidence shows that halogens are pervasive in the troposphere and need to be represented in chem.-transport models for an accurate simulation of present-day O3. Using the GEOSChem model we show that tropospheric halogen chem. is likely more active in the present day than in the preindustrial. This is due to increased oceanic iodine emissions driven by increased surface O3, higher anthropogenic emissions of bromo-carbons, and an increased flux of bromine from the stratosphere. We calc. preindustrial to present-day increases in the tropospheric O3 burden of 113 Tg without halogens but only 90 Tg with, leading to a redn. in RFTO3 from 0.43 to 0.35Wm-2. We attribute ∼ 50% of this redn. to increased bromine flux from the stratosphere, ∼ 35% to the ocean-atm. iodine feedback, and ∼ 15% to increased tropospheric sources of anthropogenic halogens. This redn. of tropospheric O3 radiative forcing due to halogens (0.087Wm-2) is greater than that from the radiative forcing of stratospheric O3 (∼ 0.05Wm-2). Ests. of RFTO3 that fail to consider halogen chem. are likely overestimates ( ∼ 25%).
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  4. 4
    Carpenter, L. J.; MacDonald, S. M.; Shaw, M. D.; Kumar, R.; Saunders, R. W.; Parthipan, R.; Wilson, J.; Plane, J. M. C. Atmospheric iodine levels influenced by sea surface emissions of inorganic iodine. Nat. Geosci. 2013, 6 (2), 108– 111,  DOI: 10.1038/ngeo1687
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    4
    Atmospheric iodine levels influenced by sea surface emissions of inorganic iodine
    Carpenter, Lucy J.; MacDonald, Samantha M.; Shaw, Marvin D.; Kumar, Ravi; Saunders, Russell W.; Parthipan, Rajendran; Wilson, Julie; Plane, John M. C.
    Nature Geoscience (2013), 6 (2), 108-111CODEN: NGAEBU; ISSN:1752-0894. (Nature Publishing Group)
    Naturally occurring bromine- and iodine-contg. compds. substantially reduce regional, and possibly even global, tropospheric ozone levels. As such, these halogen gases reduce the global warming effects of ozone in the troposphere, and its capacity to initiate the chem. removal of hydrocarbons such as methane. The majority of halogen-related surface ozone destruction is attributable to iodine chem. So far, org. iodine compds. have been assumed to serve as the main source of oceanic iodine emissions. However, known org. sources of atm. iodine cannot account for gas-phase iodine oxide concns. in the lower troposphere over the tropical oceans. Here, we quantify gaseous emissions of inorg. iodine following the reaction of iodide with ozone in a series of lab. expts. We show that the reaction of iodide with ozone leads to the formation of both mol. iodine and hypoiodous acid. Using a kinetic box model of the sea surface layer and a one-dimensional model of the marine boundary layer, we show that the reaction of ozone with iodide on the sea surface could account for around 75% of obsd. iodine oxide levels over the tropical Atlantic Ocean. According to the sea surface model, hypoiodous acid-not previously considered as an oceanic source of iodine-is emitted at a rate ten-fold higher than that of mol. iodine under ambient conditions.
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  5. 5
    Wang, S.; Schmidt, J. A.; Baidar, S.; Coburn, S.; Dix, B.; Koenig, T. K.; Apel, E.; Bowdalo, D.; Campos, T. L.; Eloranta, E.; Evans, M. J.; DiGangi, J. P.; Zondlo, M. A.; Gao, R.-S.; Haggerty, J. A.; Hall, S. R.; Hornbrook, R. S.; Jacob, D.; Morley, B.; Pierce, B.; Reeves, M.; Romashkin, P.; ter Schure, A.; Volkamer, R. Active and widespread halogen chemistry in the tropical and subtropical free troposphere. Proc. Natl. Acad. Sci. U. S. A. 2015, 112 (30), 9281– 9286,  DOI: 10.1073/pnas.1505142112
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    5
    Active and widespread halogen chemistry in the tropical and subtropical free troposphere
    Wang, Siyuan; Schmidt, Johan A.; Baidar, Sunil; Coburn, Sean; Dix, Barbara; Koenig, Theodore K.; Apel, Eric; Bowdalo, Dene; Campos, Teresa L.; Eloranta, Ed; Evans, Mathew J.; DiGangi, Joshua P.; Zondlo, Mark A.; Gao, Ru-Shan; Haggerty, Julie A.; Hall, Samuel R.; Hornbrook, Rebecca S.; Jacob, Daniel; Morley, Bruce; Pierce, Bradley; Reeves, Mike; Romashkin, Pavel; ter Schure, Arnout; Volkamer, Rainer
    Proceedings of the National Academy of Sciences of the United States of America (2015), 112 (30), 9281-9286CODEN: PNASA6; ISSN:0027-8424. (National Academy of Sciences)
    Halogens in the troposphere are increasingly recognized as playing an important role for atm. chem., and possibly climate. Bromine and iodine react catalytically to destroy ozone (O3), oxidize mercury, and modify oxidative capacity that is relevant for the lifetime of greenhouse gases. Most of the tropospheric O3 and methane (CH4) loss occurs at tropical latitudes. Here we report simultaneous measurements of vertical profiles of bromine oxide (BrO) and iodine oxide (IO) in the tropical and subtropical free troposphere (10°N to 40°S), and show that these halogens are responsible for 34% of the column-integrated loss of tropospheric O3. The obsd. BrO concns. increase strongly with altitude (∼3.4 pptv at 13.5 km), and are 2-4 times higher than predicted in the tropical free troposphere. BrO resembles model predictions more closely in stratospheric air. The largest model low bias is obsd. in the lower tropical transition layer (TTL) over the tropical eastern Pacific Ocean, and may reflect a missing inorg. bromine source supplying an addnl. 2.5-6.4 pptv total inorg. bromine (Bry), or model overestimated Bry wet scavenging. Our results highlight the importance of heterogeneous chem. on ice clouds, and imply an addnl. Bry source from the debromination of sea salt residue in the lower TTL. The obsd. levels of bromine oxidize mercury up to 3.5 times faster than models predict, possibly increasing mercury deposition to the ocean. The halogen-catalyzed loss of tropospheric O3 needs to be considered when estg. past and future ozone radiative effects.
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  6. 6
    Simpson, W. R.; Brown, S. S.; Saiz-Lopez, A.; Thornton, J. A.; von Glasow, R. Tropospheric Halogen Chemistry: Sources, Cycling, and Impacts. Chem. Rev. 2015, 115 (10), 4035– 4062,  DOI: 10.1021/cr5006638
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    6
    Tropospheric Halogen Chemistry: Sources, Cycling, and Impacts
    Simpson, William R.; Brown, Steven S.; Saiz-Lopez, Alfonso; Thornton, Joel A.; von Glasow, Roland
    Chemical Reviews (Washington, DC, United States) (2015), 115 (10), 4035-4062CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)
    A review concerning tropospheric reactive halogen chem., i.e., sources, cycling, and impacts, is given. Topics discussed include: introduction/history; synthesis of halogen chem. (halogen radical reactions, halogen sources and observations); recent advances in tropospheric halogen chem. (polar regions, marine boundary layer, NOx pollution-related halogen chem., regional and global halogen chem.); impacts of halogen chem. (O3 and troposphere oxidizing capacity, polar, marine boundary layer, polluted regions); future research needs; and conclusions.
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  7. 7
    Koenig, T. K.; Baidar, S.; Campuzano-Jost, P.; Cuevas, C. A.; Dix, B.; Fernandez, R. P.; Guo, H.; Hall, S. R.; Kinnison, D.; Nault, B. A.; Ullmann, K.; Jimenez, J. L.; Saiz-Lopez, A.; Volkamer, R. Quantitative detection of iodine in the stratosphere. Proc. Natl. Acad. Sci. U. S. A. 2020, 117 (4), 1860– 1866,  DOI: 10.1073/pnas.1916828117
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    7
    Quantitative detection of iodine in the stratosphere
    Koenig, Theodore K.; Baidar, Sunil; Campuzano-Jost, Pedro; Cuevas, Carlos A.; Dix, Barbara; Fernandez, Rafael P.; Guo, Hongyu; Hall, Samuel R.; Kinnison, Douglas; Nault, Benjamin A.; Ullmann, Kirk; Jimenez, Jose L.; Saiz-Lopez, Alfonso; Volkamer, Rainer
    Proceedings of the National Academy of Sciences of the United States of America (2020), 117 (4), 1860-1866CODEN: PNASA6; ISSN:0027-8424. (National Academy of Sciences)
    Oceanic emissions of iodine destroy ozone, modify oxidative capacity, and can form new particles in the troposphere. However, the impact of iodine in the stratosphere is highly uncertain due to the lack of previous quant. measurements. Here, we report quant. measurements of iodine monoxide radicals and particulate iodine (Iy,part) from aircraft in the stratosphere. These measurements support that 0.77 ± 0.10 parts per trillion by vol. (pptv) total inorg. iodine (Iy) is injected to the stratosphere. These high Iy amts. are indicative of active iodine recycling on ice in the upper troposphere (UT), support the upper end of recent Iy ests. (0 to 0.8 pptv) by the World Meteorol. Organization, and are incompatible with zero stratospheric iodine injection. Gas-phase iodine (Iy,gas) in the UT (0.67 ± 0.09 pptv) converts to Iy,part sharply near the tropopause. In the stratosphere, IO radicals remain detectable (0.06 ± 0.03 pptv), indicating persistent Iy,part recycling back to Iy,gas as a result of active multiphase chem. At the obsd. levels, iodine is responsible for 32% of the halogen-induced ozone loss (bromine 40%, chlorine 28%), due primarily to previously unconsidered heterogeneous chem. Anthropogenic (pollution) ozone has increased iodine emissions since preindustrial times (∼factor of 3 since 1950) and could be partly responsible for the continued decrease of ozone in the lower stratosphere. Increasing iodine emissions have implications for ozone radiative forcing and possibly new particle formation near the tropopause.
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  8. 8
    Abbatt, J. P. D.; Waschewsky, G. C. G. Heterogeneous Interactions of HOBr, HNO3, O3, and NO2 with Deliquescent NaCl Aerosols at Room Temperature. J. Phys. Chem. A 1998, 102 (21), 3719– 3725,  DOI: 10.1021/jp980932d
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    8
    Heterogeneous Interactions of HOBr, HNO3, O3, and NO2 with Deliquescent NaCl Aerosols at Room Temperature
    Abbatt, J. P. D.; Waschewsky, G. C. G.
    Journal of Physical Chemistry A (1998), 102 (21), 3719-3725CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)
    To better quantify the rates at which key trace gases interact with sea-salt aerosols, the kinetics of uptake of HOBr, HNO3, O3, and NO2 by deliquescent NaCl aerosols at 75% relative humidity (RH) and room temp. have been studied using an aerosol kinetics flow tube technique. Results for HOBr indicate that the uptake coeff. (γ) is larger than 0.2 for highly acidic aerosols at pH 0.3 and for aerosols that have been buffered to pH 7.2 using a 0.25 M NaH2PO4/Na2HPO4 buffer. For unbuffered NaCl aerosols, the HOBr uptake coeff. due to reaction is less than 1.5 × 10-3. For HNO3, the uptake coeff. on unbuffered, NaCl aerosols is greater than 0.2, being driven by the very high soly. of HNO3 in aq. salt solns. Both NO2 and O3 show low reactivity on pH neutral aerosols with upper limits to the uptake coeffs. of 10-4. With acidic aerosols, slight O3 loss occurs either on the walls of the flow tube or on the aerosols, giving rise to Cl2. These expts. are the first reported kinetics studies of the loss of HOBr, HNO3, and O3 on aq. NaCl solns., and they imply that gas-phase diffusion, and not reaction kinetics, dets. the mass-transfer rates of gas-phase HNO3 and HOBr to marine aerosols in the boundary layer. Also, the HOBr results support modeling studies which have proposed that HOBr uptake initiates autocatalytic release of bromide from sea-salt aerosols.
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  9. 9
    Simpson, W. R.; von Glasow, R.; Riedel, K.; Anderson, P.; Ariya, P.; Bottenheim, J.; Burrows, J.; Carpenter, L. J.; Frieß, U.; Goodsite, M. E.; Heard, D.; Hutterli, M.; Jacobi, H. W.; Kaleschke, L.; Neff, B.; Plane, J.; Platt, U.; Richter, A.; Roscoe, H.; Sander, R.; Shepson, P.; Sodeau, J.; Steffen, A.; Wagner, T.; Wolff, E. Halogens and their role in polar boundary-layer ozone depletion. Atmos. Chem. Phys. 2007, 7 (16), 4375– 4418,  DOI: 10.5194/acp-7-4375-2007
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    9
    Halogens and their role in polar boundary-layer ozone depletion
    Simpson, W. R.; von Glasow, R.; Riedel, K.; Anderson, P.; Ariya, P.; Bottenheim, J.; Burrows, J.; Carpenter, L. J.; Friess, U.; Goodsite, M. E.; Heard, D.; Hutterli, M.; Jacobi, H.-W.; Kaleschke, L.; Neff, B.; Plane, J.; Platt, U.; Richter, A.; Roscoe, H.; Sander, R.; Shepson, P.; Sodeau, J.; Steffen, A.; Wagner, T.; Wolff, E.
    Atmospheric Chemistry and Physics (2007), 7 (16), 4375-4418CODEN: ACPTCE; ISSN:1680-7316. (Copernicus Publications)
    A review. During springtime in the polar regions, unique photochem. converts inert halide salt ions (e.g. Br-) into reactive halogen species (e.g. Br atoms and BrO) that deplete ozone in the boundary layer to near zero levels. Since their discovery in the late 1980s, research on ozone depletion events (ODEs) has made great advances; however many key processes remain poorly understood. In this article we history, chem., dependence on environmental conditions, and impacts of ODEs are reviewed. This research has shown the central role of bromine photochem., but how salts are transported from the ocean and are oxidized to become reactive halogen species in the air is still not fully understood. Halogens other than bromine (chlorine and iodine) are also activated through incompletely understood mechanisms that are probably coupled to bromine chem. The main consequence of halogen activation is chem. destruction of ozone, which removes the primary precursor of atm. oxidn., and generation of reactive halogen atoms/oxides that become the primary oxidizing species. The different reactivity of halogens as compared to OH and ozone has broad impacts on atm. chem., including near complete removal and deposition of mercury, alteration of oxidn. fates for org. gases, and export of bromine into the free troposphere. Recent changes in the climate of the Arctic and state of the Arctic sea ice cover are likely to have strong effects on halogen activation and ODEs; however, more research is needed to make meaningful predictions of these changes.
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  10. 10
    O’Dowd, C. D.; Facchini, M. C.; Cavalli, F.; Ceburnis, D.; Mircea, M.; Decesari, S.; Fuzzi, S.; Yoon, Y. J.; Putaud, J.-P. Biogenically driven organic contribution to marine aerosol. Nature 2004, 431 (7009), 676– 680,  DOI: 10.1038/nature02959
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    10
    Biogenically driven organic contribution to marine aerosol
    O'Dowd, Colin D.; Facchini, Maria Cristina; Cavalli, Fabrizia; Ceburnis, Darius; Mircea, Mihaela; Decesari, Stefano; Fuzzi, Sandro; Yoon, Young Jun; Putaud, Jean-Philippe
    Nature (London, United Kingdom) (2004), 431 (7009), 676-680CODEN: NATUAS; ISSN:0028-0836. (Nature Publishing Group)
    Marine aerosol contributes significantly to the global aerosol load and consequently has an important impact on both the Earth's albedo and climate. So far, much of the focus on marine aerosol has centered on the prodn. of aerosol from sea-salt and non-sea-salt sulfates. Recent field expts., however, have shown that known aerosol prodn. processes for inorg. species cannot account for the entire aerosol mass that occurs in submicrometer sizes. Several exptl. studies have pointed to the presence of significant concns. of org. matter in marine aerosol. There is some information available about the compn. of org. matter, but the contribution of org. matter to marine aerosol, as a function of aerosol size, as well as its characterization as hydrophilic or hydrophobic, has been lacking. Here we measure the phys. and chem. characteristics of ≤ 1 μm marine aerosol over the North Atlantic Ocean during plankton blooms progressing from spring through to autumn. We find that during bloom periods, the org. fraction dominates and contributes 63% to the submicrometer aerosol mass (about 45% is water-insol. and about 18% water-sol.). In winter, when biol. activity is at its lowest, the org. fraction decreases to 15%. Our model simulations indicate that org. matter can enhance the cloud droplet concn. by 15% to more than 100% and is therefore an important component of the aerosol-cloud-climate feedback system involving marine biota.
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  11. 11
    Prather, K. A.; Bertram, T. H.; Grassian, V. H.; Deane, G. B.; Stokes, M. D.; DeMott, P. J.; Aluwihare, L. I.; Palenik, B. P.; Azam, F.; Seinfeld, J. H.; Moffet, R. C.; Molina, M. J.; Cappa, C. D.; Geiger, F. M.; Roberts, G. C.; Russell, L. M.; Ault, A. P.; Baltrusaitis, J.; Collins, D. B.; Corrigan, C. E.; Cuadra-Rodriguez, L. A.; Ebben, C. J.; Forestieri, S. D.; Guasco, T. L.; Hersey, S. P.; Kim, M. J.; Lambert, W. F.; Modini, R. L.; Mui, W.; Pedler, B. E.; Ruppel, M. J.; Ryder, O. S.; Schoepp, N. G.; Sullivan, R. C.; Zhao, D. Bringing the ocean into the laboratory to probe the chemical complexity of sea spray aerosol. Proc. Natl. Acad. Sci. U. S. A. 2013, 110 (19), 7550– 7555,  DOI: 10.1073/pnas.1300262110
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    11
    Bringing the ocean into the laboratory to probe the chemical complexity of sea spray aerosol
    Prather, Kimberly A.; Bertram, Timothy H.; Grassian, Vicki H.; Deane, Grant B.; Stokes, M. Dale; DeMott, Paul J.; Aluwihare, Lihini I.; Palenik, Brian P.; Azam, Farooq; Seinfeld, John H.; Moffet, Ryan C.; Molina, Mario J.; Cappa, Christopher D.; Geiger, Franz M.; Roberts, Gregory C.; Russell, Lynn M.; Ault, Andrew P.; Baltrusaitis, Jonas; Collins, Douglas B.; Corrigan, Craig E.; Cuadra-Rodriguez, Luis A.; Ebben, Carlena J.; Forestieri, Sara D.; Guasco, Timothy L.; Hersey, Scott P.; Kim, Michelle J.; Lambert, William F.; Modini, Robin L.; Mui, Wilton; Pedler, Byron E.; Ruppel, Matthew J.; Ryder, Olivia S.; Schoepp, Nathan G.; Sullivan, Ryan C.; Zhao, Defeng
    Proceedings of the National Academy of Sciences of the United States of America (2013), 110 (19), 7550-7555, S7550/1-S7550/10CODEN: PNASA6; ISSN:0027-8424. (National Academy of Sciences)
    The prodn., size, and chem. compn. of sea spray aerosol (SSA) particles strongly depend on seawater chem., which is controlled by phys., chem., and biol. processes. Despite decades of marine environment studies, a direct relationship has yet to be established between ocean biol. and physicochem. SSA properties. The ability to establish such relationships is hindered because SSA measurements are typically dominated by overwhelming background aerosol concns., even in remote marine environments. This work describes a newly developed approach to reproduce SSA chem. complexity a lab. setting, comprising a unique ocean/atm. facility equipped with actual breaking waves. A mesocosm expt., performed with natural seawater using controlled phytoplankton and heterotrophic bacteria concns., showed SSA size and chem. mixing state are acutely sensitive to the aerosol prodn. mechanism and to the type of biol. species present. The largest redn. in SSA hygroscopicity occurred as heterotrophic bacteria concns. increased, whereas phytoplankton and chlorophyll-a concns. decreased, directly corresponding to a change in mixing state in the smallest size range (60-180 nm). Using this newly developed approach to generate realistic SSA, systematic studies can now be performed to advance the fundamental understanding of the effect of ocean biol. on SSA chem. mixing state, heterogeneous reactivity, and resulting climate-relevant properties.
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  12. 12
    van Pinxteren, M.; Fomba, K. W.; Triesch, N.; Stolle, C.; Wurl, O.; Bahlmann, E.; Gong, X.; Voigtländer, J.; Wex, H.; Robinson, T. B.; Barthel, S.; Zeppenfeld, S.; Hoffmann, E. H.; Roveretto, M.; Li, C.; Grosselin, B.; Daële, V.; Senf, F.; van Pinxteren, D.; Manzi, M.; Zabalegui, N.; Frka, S.; Gašparović, B.; Pereira, R.; Li, T.; Wen, L.; Li, J.; Zhu, C.; Chen, H.; Chen, J.; Fiedler, B.; von Tümpling, W.; Read, K. A.; Punjabi, S.; Lewis, A. C.; Hopkins, J. R.; Carpenter, L. J.; Peeken, I.; Rixen, T.; Schulz-Bull, D.; Monge, M. E.; Mellouki, A.; George, C.; Stratmann, F.; Herrmann, H. Marine organic matter in the remote environment of the Cape Verde islands – an introduction and overview to the MarParCloud campaign. Atmos. Chem. Phys. 2020, 20 (11), 6921– 6951,  DOI: 10.5194/acp-20-6921-2020
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    12
    Marine organic matter in the remote environment of the Cape Verde islands - an introduction and overview to the MarParCloud campaign
    van Pinxteren, Manuela; Fomba, Khanneh Wadinga; Triesch, Nadja; Stolle, Christian; Wurl, Oliver; Bahlmann, Enno; Gong, Xianda; Voigtlaender, Jens; Wex, Heike; Robinson, Tiera-Brandy; Barthel, Stefan; Zeppenfeld, Sebastian; Hoffmann, Erik Hans; Roveretto, Marie; Li, Chunlin; Grosselin, Benoit; Daele, Veronique; Senf, Fabian; van Pinxteren, Dominik; Manzi, Malena; Zabalegui, Nicolas; Frka, Sanja; Gasparovic, BlaZenka; Pereira, Ryan; Li, Tao; Wen, Liang; Li, Jiarong; Zhu, Chao; Chen, Hui; Chen, Jianmin; Fiedler, Bjoern; von Tuempling, Wolf; Read, Katie Alana; Punjabi, Shalini; Lewis, Alastair Charles; Hopkins, James Roland; Carpenter, Lucy Jane; Peeken, Ilka; Rixen, Tim; Schulz-Bull, Detlef; Monge, Maria Eugenia; Mellouki, Abdelwahid; George, Christian; Stratmann, Frank; Herrmann, Hartmut
    Atmospheric Chemistry and Physics (2020), 20 (11), 6921-6951CODEN: ACPTCE; ISSN:1680-7324. (Copernicus Publications)
    The project MarParCloud (Marine biol. prodn., org. aerosol Particles and marine Clouds: a process chain) aims to improve our understanding of the genesis, modification and impact of marine org. matter (OM) from its biol. prodn., to its export to marine aerosol particles and, finally, to its ability to act as ice nucleating particles (INPs) and cloud condensation nuclei (CCN). A field campaign at the Cape Verde Atm. Observatory (CVAO) in the tropics in Sept.-Oct. 2017 formed the core of this project that was jointly performed with the project MARSU (MARine atm. Science Unravelled). A suite of chem., phys., biol. and meteorol. techniques was applied, and comprehensive measurements of bulk water, the sea surface microlayer (SML), cloud water and ambient aerosol particles collected at a ground based and a mountain station took place. Key variables comprised the chem. characterization of the atmospherically relevant OM components in the ocean and the atm. as well as measurements of INPs and CCN. Moreover, bacterial cell counts, mercury species and trace gases were analyzed. To interpret the results, the measurements were accompanied by various auxiliary parameters such as air mass back-trajectory anal., vertical atm. profile anal., cloud observations and pigment measurements in seawater. Addnl. modeling studies supported the exptl. anal. During the campaign, the CVAO exhibited marine air masses with low and partly moderate dust influences. The marine boundary layer was well mixed as indicated by an almost uniform particle no. size distribution within the boundary layer. Lipid biomarkers were present in the aerosol particles in typical concns. of marine background conditions. Accumulation and coarse mode particles served as CCN and were efficiently transferred to the cloud water. The ascent of ocean derived compds., such as sea salt and sugar like compds., to the cloud level, as derived from chem. anal. and atm. transfer modeling results, denotes an influence of marine emissions on cloud formation. Org. nitrogen compds. (free amino acids) were enriched by several orders of magnitude in submicron aerosol particles and in cloud water compared to seawater. However, INP measurements also indicated a significant contribution of other non marine sources to the local INP concn., as (biol. active) INPs were mainly present in supermicron aerosol particles that are not suggested to undergo strong enrichment during ocean atm. transfer. In addn., the no. of CCN at the supersatn. of 0.30% was about 2.5 times higher during dust periods compared to marine periods. Lipids, sugar like compds., UV-absorbing (UV: UV) humic like substances and low mol. wt. neutral components were important org. compds. in the seawater, and highly surface-active lipids were enriched within the SML. The selective enrichment of specific org. compds. in the SML needs to be studied in further detail and implemented in an OM source function for emission modeling to better understand transfer patterns, the mechanisms of marine OM transformation in the atm. and the role of addnl. sources. In summary, when looking at particulate mass, we see oceanic compds. transferred to the atm. aerosol and to the cloud level, while from a perspective of particle no. concns., sea spray aerosol (i.e., primary marine aerosol) contributions to both CCN and INPs are rather limited.
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  13. 13
    Mata, J.; Varade, D.; Ghosh, G.; Bahadur, P. Effect of tetrabutylammonium bromide on the micelles of sodium dodecyl sulfate. Colloids Surf., A 2004, 245 (1), 69– 73,  DOI: 10.1016/j.colsurfa.2004.07.009
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    Effect of tetrabutylammonium bromide on the micelles of sodium dodecyl sulfate
    Mata, J.; Varade, D.; Ghosh, G.; Bahadur, P.
    Colloids and Surfaces, A: Physicochemical and Engineering Aspects (2004), 245 (1-3), 69-73CODEN: CPEAEH; ISSN:0927-7757. (Elsevier B.V.)
    Micellar behavior of sodium dodecyl sulfate (NaDS) was examd. in the presence of tetrabutylammonium bromide (TBABr) by surface tension, viscosity, dynamic light scattering (DLS), dye solubilization, and cloud point measurements. NaDS showed enhanced solubilization properties and a remarkable decrease in surface tension and crit. micelle concn. (CMC) in presence of TBABr. Both viscosity and DLS showed growth in NaDS micelles (50 mM) above 100 mM TBABr concn.; sphere-to-rod transition and micellar growth obsd. till 200 mM, above which soln. undergoes phase sepn. The results are explained on the basis of the binding ability of bulky tetrabutylammonium ion on NaDS.
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  14. 14
    Cochran, R. E.; Ryder, O. S.; Grassian, V. H.; Prather, K. A. Sea Spray Aerosol: The Chemical Link between the Oceans, Atmosphere, and Climate. Acc. Chem. Res. 2017, 50 (3), 599– 604,  DOI: 10.1021/acs.accounts.6b00603
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    14
    Sea Spray Aerosol: The Chemical Link between the Oceans, Atmosphere, and Climate
    Cochran, Richard E.; Ryder, Olivia S.; Grassian, Vicki H.; Prather, Kimberly A.
    Accounts of Chemical Research (2017), 50 (3), 599-604CODEN: ACHRE4; ISSN:0001-4842. (American Chemical Society)
    To make connections between lab. and field study results, unique approaches have been developed to bring real-world complexity of sea spray aerosols (SSA) into the lab. to allow direct investigation of microscopic and mol. processes. From these studies, it was discovered that nascent SSA contains a highly diverse population of particles with respect to chem. compn. which is directly affected by dynamic phys. and biol. processes occurring in the ocean. While some properties of nascent SSA, including ice nucleating ability and particle morphol., have displayed strong changes in response to microbial-induced alterations to SSA chem. compn., others, such as cloud condensation nuclei propensity and heterogeneous reactions with certain trace gases remain surprisingly unaffected. Results of gas-phase mols. and water uptake by nascent SSA has been shown to differ from those obtained using simple model system. This suggests the interfacial chem. of nascent SSA involves a synergistic array of multiple processes and interactions. Topics discussed include: ocean and atm. inter-connected through chem.; producing representative SSA; understanding the effect of interfacial interactions and ocean biol. on SSA compn.; chem.-driven interactions among SSA, trace atm. gases, and water; and summary and future prospects.
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  15. 15
    Ciuraru, R.; Fine, L.; van Pinxteren, M.; D’Anna, B.; Herrmann, H.; George, C. Photosensitized production of functionalized and unsaturated organic compounds at the air-sea interface. Sci. Rep. 2015, 5 (1), 12741,  DOI: 10.1038/srep12741
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    15
    Photosensitized production of functionalized and unsaturated organic compounds at the air-sea interface
    Ciuraru, Raluca; Fine, Ludovic; van Pinxteren, Manuela; D'Anna, Barbara; Herrmann, Hartmut; George, Christian
    Scientific Reports (2015), 5 (), 12741CODEN: SRCEC3; ISSN:2045-2322. (Nature Publishing Group)
    The sea-surface microlayer (SML) has different phys., chem. and biol. properties compared to the subsurface water, with an enrichment of org. matter i.e., dissolved org. matter including UV absorbing humic substances, fatty acids and many others. Here we present exptl. evidence that dissolved org. matter, such as humic acids, when exposed to sunlight, can photosensitize the chem. conversion of linear satd. fatty acids at the air-water interface into unsatd. functionalized gas phase products (i.e. satd. and unsatd. aldehydes and acids, alkenes and dienes,...) which are known precursors of secondary org. aerosols. These functionalized mols. have previously been thought to be of biol. origin, but here we demonstrate that abiotic interfacial photochem. has the potential to produce such mols. As the ocean is widely covered by the SML, this new understanding will impact on our ability to describe atm. chem. in the marine environment.
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  16. 16
    Alpert, P. A.; Ciuraru, R.; Rossignol, S.; Passananti, M.; Tinel, L.; Perrier, S.; Dupart, Y.; Steimer, S. S.; Ammann, M.; Donaldson, D. J.; George, C. Fatty Acid Surfactant Photochemistry Results in New Particle Formation. Sci. Rep. 2017, 7 (1), 12693,  DOI: 10.1038/s41598-017-12601-2
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    16
    Fatty Acid Surfactant Photochemistry Results in New Particle Formation
    Alpert Peter A; Ciuraru Raluca; Rossignol Stephanie; Passananti Monica; Tinel Liselotte; Perrier Sebastien; Dupart Yoan; George Christian; Alpert Peter A; Steimer Sarah S; Ammann Markus; Ciuraru Raluca; Rossignol Stephanie; Passananti Monica; Tinel Liselotte; Steimer Sarah S; Donaldson D James
    Scientific reports (2017), 7 (1), 12693 ISSN:.
    Organic interfaces that exist at the sea surface microlayer or as surfactant coatings on cloud droplets are highly concentrated and chemically distinct from the underlying bulk or overlying gas phase. Therefore, they may be potentially unique locations for chemical or photochemical reactions. Recently, photochemical production of volatile organic compounds (VOCs) was reported at a nonanoic acid interface however, subsequent secondary organic aerosol (SOA) particle production was incapable of being observed. We investigated SOA particle formation due to photochemical reactions occurring at an air-water interface in presence of model saturated long chain fatty acid and alcohol surfactants, nonanoic acid and nonanol, respectively. Ozonolysis of the gas phase photochemical products in the dark or under continued UV irradiation both resulted in nucleation and growth of SOA particles. Irradiation of nonanol did not yield detectable VOC or SOA production. Organic carbon functionalities of the SOA were probed using X-ray microspectroscopy and compared with other laboratory generated and field collected particles. Carbon-carbon double bonds were identified in the condensed phase which survived ozonolysis during new particle formation and growth. The implications of photochemical processes occurring at organic coated surfaces are discussed in the context of marine SOA particle atmospheric fluxes.
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  17. 17
    Ammann, M.; Cox, R. A.; Crowley, J. N.; Jenkin, M. E.; Mellouki, A.; Rossi, M. J.; Troe, J.; Wallington, T. J. Evaluated kinetic and photochemical data for atmospheric chemistry: Volume VI – heterogeneous reactions with liquid substrates. Atmos. Chem. Phys. 2013, 13 (16), 8045– 8228,  DOI: 10.5194/acp-13-8045-2013
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    17
    Evaluated kinetic and photochemical data for atmospheric chemistry: Volume VI - heterogeneous reactions with liquid substrates
    Ammann, M.; Cox, R. A.; Crowley, J. N.; Jenkin, M. E.; Mellouki, A.; Rossi, M. J.; Troe, J.; Wallington, T. J.
    Atmospheric Chemistry and Physics (2013), 13 (16), 8045-8228, 184 pp.CODEN: ACPTCE; ISSN:1680-7324. (Copernicus Publications)
    A review. This article, the sixth in the ACP journal series, presents data evaluated by the IUPAC Task Group on Atm. Chem. Kinetic Data Evaluation. It covers the heterogeneous processes involving liq. particles present in the atm. with an emphasis on those relevant for the upper troposphere/lower stratosphere and the marine boundary layer, for which uptake coeffs. and adsorption parameters have been presented on the IUPAC website since 2009. The article consists of an introduction and guide to the evaluation, giving a unifying framework for parameterisation of atm. heterogeneous processes. We provide summary sheets contg. the recommended uptake parameters for the evaluated processes. The exptl. data on which the recommendations are based are provided in data sheets in sep. appendices for the four surfaces considered: liq. water, deliquesced halide salts, other aq. electrolytes and sulfuric acid.
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  18. 18
    Clifford, D.; Donaldson, D. J. Direct Experimental Evidence for a Heterogeneous Reaction of Ozone with Bromide at the Air–Aqueous Interface. J. Phys. Chem. A 2007, 111 (39), 9809– 9814,  DOI: 10.1021/jp074315d
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    18
    Direct Experimental Evidence for a Heterogeneous Reaction of Ozone with Bromide at the Air-Aqueous Interface
    Clifford, Daniel; Donaldson, D. J.
    Journal of Physical Chemistry A (2007), 111 (39), 9809-9814CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)
    Recent exptl. and theor. evidence has indicated an enhancement of the heavier halide ions at the air-aq. interface, relative to their bulk concns. This, along with an order of magnitude discrepancy between measured and predicted Br2 prodn. in the reaction of ozone with deliquesced NaBr aerosol, has led to the suggestion that an interface reaction occurs between ozone and bromide. We have used harmine, a β-carboline alkaloid, as an interface-sensitive fluorescent pH probe in order to measure pH changes assocd. with the interfacial reaction of ozone and bromide. The rate of pH change depends upon the bulk bromide concn. in a way which is well described by a Langmuir-Hinshelwood kinetic model. In the presence of octanol at the interface, the rate of pH change tracks the octanol adsorption isotherm, as expected if octanol enhances the concn. of ozone at the surface.
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  19. 19
    Oldridge, N. W.; Abbatt, J. P. D. Formation of Gas-Phase Bromine from Interaction of Ozone with Frozen and Liquid NaCl/NaBr Solutions: Quantitative Separation of Surficial Chemistry from Bulk-Phase Reaction. J. Phys. Chem. A 2011, 115 (12), 2590– 2598,  DOI: 10.1021/jp200074u
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    19
    Formation of Gas-Phase Bromine from Interaction of Ozone with Frozen and Liquid NaCl/NaBr Solutions: Quantitative Separation of Surficial Chemistry from Bulk-Phase Reaction
    Oldridge, N. W.; Abbatt, J. P. D.
    Journal of Physical Chemistry A (2011), 115 (12), 2590-2598CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)
    The formation kinetics of gas-phase bromine (Br2) from interaction of gas-phase ozone (O3) with frozen and liq. solns. of NaCl (0.55 M) and NaBr (largely from 1.7 to 8.5 mM) have been studied from -40° to 0° in a coated-wall flow tube coupled to a chem. ionization mass spectrometer. The reactive uptake coeff. for O3 is deduced from the product formation rate and then studied as a function of exptl. conditions. In particular, for both the liq. and frozen solns., we find that the uptake coeff. is inversely dependent on the gas-phase O3 concn. in a manner that is quant. consistent with both surface- and bulk-phase kinetics. The reaction is fastest on acidic media (pH of the starting soln. down to 2) but also proceeds at an appreciable rate on neutral substrates. Above 253 K, the uptake coeff. increases with increasing temp. on frozen solns., consistent with an increasing brine content. The similarity of the abs. magnitude and form of the kinetics on the frozen and liq. substrates suggests that the reaction on the frozen soln. is occurring with the assocd. brine, and not with the ice bulk or a quasi-liq. layer existing on the ice. The implications of these results to bromine activation in the tropospheric boundary layer are made.
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  20. 20
    Artiglia, L.; Edebeli, J.; Orlando, F.; Chen, S.; Lee, M.-T.; Corral Arroyo, P.; Gilgen, A.; Bartels-Rausch, T.; Kleibert, A.; Vazdar, M.; Andres Carignano, M.; Francisco, J. S.; Shepson, P. B.; Gladich, I.; Ammann, M. A surface-stabilized ozonide triggers bromide oxidation at the aqueous solution-vapour interface. Nat. Commun. 2017, 8 (1), 700,  DOI: 10.1038/s41467-017-00823-x
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    20
    A surface-stabilized ozonide triggers bromide oxidation at the aqueous solution-vapour interface
    Artiglia Luca; Edebeli Jacinta; Orlando Fabrizio; Chen Shuzhen; Lee Ming-Tao; Corral Arroyo Pablo; Gilgen Anina; Bartels-Rausch Thorsten; Ammann Markus; Artiglia Luca; Edebeli Jacinta; Chen Shuzhen; Gilgen Anina; Lee Ming-Tao; Corral Arroyo Pablo; Kleibert Armin; Vazdar Mario; Andres Carignano Marcelo; Gladich Ivan; Francisco Joseph S; Shepson Paul B
    Nature communications (2017), 8 (1), 700 ISSN:.
    Oxidation of bromide in aqueous environments initiates the formation of molecular halogen compounds, which is important for the global tropospheric ozone budget. In the aqueous bulk, oxidation of bromide by ozone involves a [Br•OOO(-)] complex as intermediate. Here we report liquid jet X-ray photoelectron spectroscopy measurements that provide direct experimental evidence for the ozonide and establish its propensity for the solution-vapour interface. Theoretical calculations support these findings, showing that water stabilizes the ozonide and lowers the energy of the transition state at neutral pH. Kinetic experiments confirm the dominance of the heterogeneous oxidation route established by this precursor at low, atmospherically relevant ozone concentrations. Taken together, our results provide a strong case of different reaction kinetics and mechanisms of reactions occurring at the aqueous phase-vapour interface compared with the bulk aqueous phase.Heterogeneous oxidation of bromide in atmospheric aqueous environments has long been suspected to be accelerated at the interface between aqueous solution and air. Here, the authors provide spectroscopic, kinetic and theoretical evidence for a rate limiting, surface active ozonide formed at the interface.
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  21. 21
    Edebeli, J.; Ammann, M.; Bartels-Rausch, T. Microphysics of the aqueous bulk counters the water activity driven rate acceleration of bromide oxidation by ozone from 289–245 K. Environ. Sci.: Processes Impacts 2019, 21 (1), 63– 73,  DOI: 10.1039/C8EM00417J
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    21
    Microphysics of the aqueous bulk counters the water activity driven rate acceleration of bromide oxidation by ozone from 289-245 K
    Edebeli, Jacinta; Ammann, Markus; Bartels-Rausch, Thorsten
    Environmental Science: Processes & Impacts (2019), 21 (1), 63-73CODEN: ESPICZ; ISSN:2050-7895. (Royal Society of Chemistry)
    The reaction of ozone with bromide is an initiation process in bromine activation resulting in the formation of reactive bromine species with impacts on the fate of compds. in the lower atm. Environmental halide sources often contain orgs., which are known to influence aq. bulk reactivity. Here, we present a study investigating the temp. dependence of bromide oxidn. by ozone using a coated wall flow tube reactor coated with an aq. mixt. of citric acid, as a proxy for oxidized secondary org. matter, and sodium bromide. Using the resistor model formulation, we quantify changes in the properties of the aq. bulk relevant for the obsd. reactivity. The reactive uptake coeff. decreased from 2 × 10-6 at 289 K to 0.5 × 10-6 at 245 K. Our anal. indicates that the humidity-driven increase in concn. with a corresponding increase in the pseudo-first order reaction rate was countered by the colligative change in ozone soly. and the effect of the org. fraction via increased viscosity and decreased diffusivity of ozone as the temp. decreased. From our parameterization, we provide an extension of the temp. dependence of the reaction rate coeffs. driving the oxidn. of bromide, and assess the temp.-dependent salting effects of citric acid on ozone soly. This study shows the effects of the org. species at relatively mild temps., between the f.p. and eutectic temp. of sea as is typical for the Earth's cryosphere. Thus, this study may be relevant for atm. models at different scales describing halogen activation in the marine boundary layer or free troposphere including matrixes such as sea-spray aerosol and brine in sea ice, snow, and around mid-latitude salt lakes.
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  22. 22
    Sakamoto, Y.; Goda, M.; Hirokawa, J. Kinetics Study of Heterogeneous Bromine Release from the Reaction between Gaseous Ozone and Aqueous Bromide Solution. J. Phys. Chem. A 2018, 122 (10), 2723– 2731,  DOI: 10.1021/acs.jpca.7b12819
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    22
    Kinetics Study of Heterogeneous Bromine Release from the Reaction between Gaseous Ozone and Aqueous Bromide Solution
    Sakamoto, Yosuke; Goda, Motoki; Hirokawa, Jun
    Journal of Physical Chemistry A (2018), 122 (10), 2723-2731CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)
    The heterogeneous release of mol. bromine, Br2, from the reaction between gaseous ozone and aq. bromide ion in seawater ice and sea salt aerosols is considered to be an initial source of reactive bromine species in the troposphere. Recent studies have demonstrated that the uptake of ozone by aq. bromide soln. is promoted by reactions at the gas-liq. interface. The present work investigated the heterogeneous reaction between gaseous ozone and aq. bromide soln. at atm. pressure and room temp. using a wetted wall flow reactor combined with a chem. ionization mass spectrometer. The emission rate of Br2 was measured as a function of gaseous ozone concn., aq. bromide concn., and pH. In addn., we conducted a simple kinetics model simulation that included only bulk aq.-phase reactions and compared the theor. values with the exptl. detd. values. The Br2 emission rates measured exptl. differ from the simulated rates at relatively high bromide concn., as well as in the pH region of 6-9. These differences might be explained by different Br- concn. and/or deprotonation efficiency near the interface region and those in the bulk soln.
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  23. 23
    Jung, Y.; Hong, E.; Kwon, M.; Kang, J.-W. A kinetic study of ozone decay and bromine formation in saltwater ozonation: Effect of O3 dose, salinity, pH, and temperature. Chem. Eng. J. 2017, 312, 30– 38,  DOI: 10.1016/j.cej.2016.11.113
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    23
    A kinetic study of ozone decay and bromine formation in saltwater ozonation: Effect of O3 dose, salinity, pH, and temperature
    Jung, Youmi; Hong, Eunkyung; Kwon, Minhwan; Kang, Joon-Wun
    Chemical Engineering Journal (Amsterdam, Netherlands) (2017), 312 (), 30-38CODEN: CMEJAJ; ISSN:1385-8947. (Elsevier B.V.)
    Saltwater ozonization is used to remove invasive or pathogenic organisms from ballast water and water in the aquaculture industry. Ozone chem. in saltwater is considerably different to that in freshwater. In saltwater, ozone rapidly decomps. to produce bromine, which is a main disinfectant in saltwater ozonization. It is very difficult to sep. ozone and bromine in saltwater ozonization. In this study, we developed a model for prediction of residual ozone and bromine concns., and applied this model to calc. Ct value (Concn. of disinfectant x Contact time) for disinfection. The contributions of ozone-Ct and bromine-Ct to organism removal were studied using the zooplankton, Artemia salina. Interestingly, the removal efficiency of saltwater ozonization for A. salina (47%) was the same as the sum of the removal efficiencies for bromine (32%) and ozone (14%) used on their own. This indicates that both bromine and trace ozone kill A. salina during saltwater ozonization. The prediction model for residual ozone and bromine formation was verified in different ozone dose, water salinity, pH, and temp., which affect ozone decompn. and bromine formation.
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  24. 24
    Moreno, C.; Baeza-Romero, M. T. A kinetic model for ozone uptake by solutions and aqueous particles containing I– and Br–, including seawater and sea-salt aerosol. Phys. Chem. Chem. Phys. 2019, 21 (36), 19835– 19856,  DOI: 10.1039/C9CP03430G
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    24
    A kinetic model for ozone uptake by solutions and aqueous particles containing I- and Br-, including seawater and sea-salt aerosol
    Moreno, Carolina; Baeza-Romero, Maria Teresa
    Physical Chemistry Chemical Physics (2019), 21 (36), 19835-19856CODEN: PPCPFQ; ISSN:1463-9076. (Royal Society of Chemistry)
    The heterogeneous interactions of gaseous ozone (O3) with seawater and with sea-salt aerosols are known to generate volatile halogen species, which, in turn, lead to further destruction of O3. Here, a kinetic model for the interaction of ozone (O3) with Br- and I- solns. and aq. particles has been proposed that satisfactorily explains previous literature studies about this process. Apart from the aq.-phase reactions X- + O3 (X = I, Br), the interaction also involves the surface reactions X- + O3 that occur via O3 adsorption on the aq. surface. In single salt solns. and aerosols, the partial order in ozone and the total order of the surface reactions are one, but the apparent total order is second order because the no. of ozone sites where reaction can occur is equal to the surficial concn. of X- ([X-]surf). In the presence of Cl-, the surface reactions are enhanced by a factor equal to 1 + krX-[Cl-]surf where krI- ≈ 3 x 10-4. Therefore, we have inferred that Cl- acts as a catalyst in the surface reactions X- + O3. The model has been applied to est. ozone uptake by the reaction with these halides in/on seawater and in/on sea-salt aerosol, where it has been concluded that the Cl--catalyzed surface reaction is important relative to total ozone uptake and should therefore be considered to model Y/YO (Y = I, Br, Cl) levels in the troposphere.
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  25. 25
    Hunt, S. W.; Roeselová, M.; Wang, W.; Wingen, L. M.; Knipping, E. M.; Tobias, D. J.; Dabdub, D.; Finlayson-Pitts, B. J. Formation of Molecular Bromine from the Reaction of Ozone with Deliquesced NaBr Aerosol: Evidence for Interface Chemistry. J. Phys. Chem. A 2004, 108 (52), 11559– 11572,  DOI: 10.1021/jp0467346
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    25
    Formation of Molecular Bromine from the Reaction of Ozone with Deliquesced NaBr Aerosol: Evidence for Interface Chemistry
    Hunt, S. W.; Roeselova, M.; Wang, W.; Wingen, L. M.; Knipping, E. M.; Tobias, D. J.; Dabdub, D.; Finlayson-Pitts, B. J.
    Journal of Physical Chemistry A (2004), 108 (52), 11559-11572CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)
    The reaction of ozone with aq. sodium bromide particles is investigated with a combination of aerosol chamber expts., kinetics modeling, and mol. dynamics simulations. The mol. bromine prodn. in the chamber expts. is approx. an order of magnitude greater than that predicted by known chem. in the gas and bulk aq. phases with use of a comprehensive computer kinetics model. Mol. dynamics simulations indicate that ozone has significant residence time at the air-soln. interface, while making frequent contacts with bromide ions for as long as 50 ps in the surface layer of a 6.1 M NaBr soln. The formation of a complex between ozone and bromide ion, [O3···Br-], which can lead to prodn. of Br2 by reaction at the air-water interface, is therefore feasible. Exptl. obsd. Br2 is well predicted by including an interface process with a reaction probability of [1.9 ± 0.8] × 10-6 (1 s) as the first step in a surface mechanism to produce addnl. gas-phase Br2. An est. of the impact of this interface reaction on bromine formation in the marine boundary layer shows that several ppt of bromine could potentially be produced during the night from this proposed surface chem.
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    Oum, K. W.; Lakin, M. J.; Finlayson-Pitts, B. J. Bromine activation in the troposphere by the dark reaction of O3 with seawater ice. Geophys. Res. Lett. 1998, 25 (21), 3923– 3926,  DOI: 10.1029/1998GL900078
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    26
    Bromine activation in the troposphere by the dark reaction of O3 with seawater ice
    Oum, K. W.; Lakin, M. J.; Finlayson-Pitts, B. J.
    Geophysical Research Letters (1998), 25 (21), 3923-3926CODEN: GPRLAJ; ISSN:0094-8276. (American Geophysical Union)
    There is increasing evidence that Br2 atoms play a role in tropospheric chem. in the marine boundary layer. In addn., they are believed to lead to rapid depletion of surface level O3 in the Arctic at polar sunrise. While mechanisms have been proposed for recycling Br2 atoms from sea salt particles, the initial reaction(s) leading to the formation of Br atom precursors is not known. Formation of gaseous Br2 from the reaction of seawater ice with O3 in the dark is reported. These observations suggested this reaction is a potential source of tropospheric photolyzable Br2 in high latitude coastal regions in winter. In addn., it may be the source of the photolyzable Br2 gas measured recently in the Arctic by G.A. Impey, et al. (1997), believed to be responsible for O3 destruction at polar sunrise.
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    Liu, Q.; Schurter, L. M.; Muller, C. E.; Aloisio, S.; Francisco, J. S.; Margerum, D. W. Kinetics and Mechanisms of Aqueous Ozone Reactions with Bromide, Sulfite, Hydrogen Sulfite, Iodide, and Nitrite Ions. Inorg. Chem. 2001, 40 (17), 4436– 4442,  DOI: 10.1021/ic000919j
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    27
    Kinetics and Mechanisms of Aqueous Ozone Reactions with Bromide, Sulfite, Hydrogen Sulfite, Iodide, and Nitrite Ions
    Liu, Qian; Schurter, Lynn M.; Muller, Charles E.; Aloisio, Simone; Francisco, Joseph S.; Margerum, Dale W.
    Inorganic Chemistry (2001), 40 (17), 4436-4442CODEN: INOCAJ; ISSN:0020-1669. (American Chemical Society)
    Reactions of ozone with Br-, SO32-, HSO3-, I-, and NO2-, studied by stopped-flow and pulsed-accelerated-flow techniques, are 1st order in the concn. of O3(aq) and 1st order in the concn. of each anion. The rate consts. increase by a factor of 5 × 106 as the nucleophilicities of the anions increase from Br- to SO32-. Ozone adducts with the nucleophiles are proposed as steady-state intermediates prior to oxygen atom transfer with release of O2. Ab initio calcns. show possible structures for the intermediates. The reaction between Br- and O3 is accelerated by H+ but exhibits a kinetic satn. effect as the acidity increases. The kinetics indicate formation of BrOOO- as a steady-state intermediate with an acid-assisted step to give BrOH and O2. Temp. dependencies of the reactions of Br- and HSO3- with O3 in acidic solns. are detd. from 1 to 25°. These kinetics are important in studies of annual ozone depletion in the Arctic troposphere at polar sunrise.
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    Donaldson, D. J.; Anderson, D. Does molecular HNO3 adsorb onto sulfuric acid droplet surfaces?. Geophys. Res. Lett. 1999, 26 (24), 3625– 3628,  DOI: 10.1029/1999GL010894
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    Does molecular HNO3 adsorb onto sulfuric acid droplet surfaces?
    Donaldson, D. J.; Anderson, Darren
    Geophysical Research Letters (1999), 26 (24), 3625-3628CODEN: GPRLAJ; ISSN:0094-8276. (American Geophysical Union)
    Room temp. surface tension measurements on the ternary system: nitric acid-sulfuric acid-water are reported. There is a dramatic decrease in the surface tension of sulfuric acid-water solns. as nitric acid is added. This decrease is most pronounced in the stratospherically-relevant range of sulfuric acid concns., between 50 and 75 wt% sulfuric acid. The surface tension decrease indicates a change in surface energy and surface compn. and/or structure assocd. with partitioning of mol. HNO3 to the surface. The presence of HNO3 at the surface may be related to the reported changes in heterogeneous reactivity of sulfuric acid solns. when exposed to nitric acid.
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    Ammann, M.; Artiglia, L.; Bartels-Rausch, T. Chapter 6 - X-Ray Excited Electron Spectroscopy to Study Gas–Liquid Interfaces of Atmospheric Relevance. In Physical Chemistry of Gas-Liquid Interfaces; Faust, J. A., House, J. E., Eds.; Elsevier, 2018; pp 135– 166.
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    Öhrwall, G.; Prisle, N. L.; Ottosson, N.; Werner, J.; Ekholm, V.; Walz, M.-M.; Björneholm, O. Acid–Base Speciation of Carboxylate Ions in the Surface Region of Aqueous Solutions in the Presence of Ammonium and Aminium Ions. J. Phys. Chem. B 2015, 119 (10), 4033– 4040,  DOI: 10.1021/jp509945g
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    Acid-base speciation of carboxylate ions in the surface region of aqueous solutions in the presence of ammonium and aminium ions
    Ohrwall Gunnar; Prisle Nonne L; Ottosson Niklas; Werner Josephina; Ekholm Victor; Walz Marie-Madeleine; Bjorneholm Olle
    The journal of physical chemistry. B (2015), 119 (10), 4033-40 ISSN:.
    The acid-base speciation of surface-active carboxylate ions in the surface region of aqueous solutions was studied with synchrotron-radiation-based photoelectron spectroscopy. The protonated form was found at an extraordinarily large fraction compared to that expected from the bulk pH. When adding salts containing the weak acid NH4(+) to the solution, the fraction of the acidic form at the surface increases, and to a much greater extent than expected from the bulk pH of the solution. We show that ammonium ions also are overrepresented in the surface region, and propose that the interaction between the surface-active anionic carboxylates and cationic ammonium ions creates a carboxylate-ammonium bilayer close to the surface, which increases the probability of the protonation of the carboxylate ions. By comparing the situation when a salt of the less volatile amine diethanolamine is used, we also show that the observed evaporation of ammonia that occurs after such an event only affects the equilibrium marginally.
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    Prisle, N.; Ottosson, N.; Öhrwall, G.; Söderström, J.; Maso, M. D.; Björneholm, O. Surface/bulk partitioning and acid/base speciation of aqueous decanoate: direct observations and atmospheric implications. Atmos. Chem. Phys. 2012, 12 (24), 12227– 12242,  DOI: 10.5194/acp-12-12227-2012
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    Surface/bulk partitioning and acid/base speciation of aqueous decanoate: direct observations and atmospheric implications
    Prisle, N. L.; Ottosson, N.; Ohrwall, G.; Soderstrom, J.; Dal Maso, M.; Bjorneholm, O.
    Atmospheric Chemistry and Physics (2012), 12 (24), 12227-12242CODEN: ACPTCE; ISSN:1680-7316. (Copernicus Publications)
    Dil. aq. solns. of the atm. org. surfactant sodium decanoate have been studied using surface sensitive XPS combined with synchrotron radiation. The decanoate/decanoic acid speciation and preferential adsorption was studied at the vapor-liq. interface, and the responses to mixing in soln. with some of the most common atm. inorg. ions, Na+, NH+4, Cl-, and SO2-4. Little or no influence of Na+, Cl-, or SO2-4 ions was obsd., on neither the relative speciation nor the individual adsorption properties of decanoate and decanoic acid. In particular, no significant salting-out effect due to common Na+ cations of the org. and inorg. salts was obsd. for these solns. On the other hand, mixing with NH+4 cations resulted in a pronounced surface enhancement of decanoic acid, which is attributed to surface specific acid-base chem. These changes in surface/bulk partitioning and surface speciation may significantly affect properties of aq. droplets contg. decanoate/decanoic acid, and potential implications for several processes crit. to the climate effects of atm. aerosols are discussed.
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    Lee, M.-T.; Brown, M. A.; Kato, S.; Kleibert, A.; Türler, A.; Ammann, M. Competition between organics and bromide at the aqueous solution–air interface as seen from ozone uptake kinetics and X-ray photoelectron spectroscopy. J. Phys. Chem. A 2015, 119 (19), 4600– 4608,  DOI: 10.1021/jp510707s
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    Competition between Organics and Bromide at the Aqueous Solution-Air Interface as Seen from Ozone Uptake Kinetics and X-ray Photoelectron Spectroscopy
    Lee, Ming-Tao; Brown, Matthew A.; Kato, Shunsuke; Kleibert, Armin; Turler, Andreas; Ammann, Markus
    Journal of Physical Chemistry A (2015), 119 (19), 4600-4608CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)
    Reaction of ozone (O3) with NaBr solns. in the presence and absence of citric acid (C6H8O7) under ambient conditions has been studied. Citric acid was used as a proxy for oxidized org. material present at the ocean surface or in sea spray aerosol. On neat NaBr solns., the obsd. kinetics was consistent with bulk reaction-limited uptake, and a second-order rate const. for the reaction of O3 + Br- is 57 ± 10 M-1 s-1. On mixed NaBr-citric acid aq. solns., the uptake kinetics was faster than that predicted by bulk reaction-limited uptake and also faster than expected based on an acid-catalyzed mechanism. XPS spectra on a liq. microjet of the same solns. at 1.0·10-3-1.0·10-4 mbar was used to obtain quant. insight into the interfacial compn. relative to that of the bulk solns. It revealed that the bromide anion was depleted by 30 ± 10% while the sodium cation gets enhanced by 40 ± 20% at the aq. soln.-air interface of a 0.12 M NaBr soln. mixed with 2.5 M citric acid in the bulk, attributed to the role of citric acid as a weak surfactant. Therefore, the enhanced reactivity of bromide solns. obsd. in the presence of citric acid was not necessarily attributable to a surface reaction but could also result from an increased soly. of ozone at higher citric acid concns. Whether the acid-catalyzed chem. may have a larger effect on the surface than in the bulk to offset the effect of bromide depletion also remains open.
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    Lee, M.-T.; Orlando, F.; Khabiri, M.; Roeselová, M.; Brown, M. A.; Ammann, M. The opposing effect of butanol and butyric acid on the abundance of bromide and iodide at the aqueous solution–air interface. Phys. Chem. Chem. Phys. 2019, 21 (16), 8418– 8427,  DOI: 10.1039/C8CP07448H
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    The opposing effect of butanol and butyric acid on the abundance of bromide and iodide at the aqueous solution-air interface
    Lee, Ming-Tao; Orlando, Fabrizio; Khabiri, Morteza; Roeselova, Martina; Brown, Matthew A.; Ammann, Markus
    Physical Chemistry Chemical Physics (2019), 21 (16), 8418-8427CODEN: PPCPFQ; ISSN:1463-9076. (Royal Society of Chemistry)
    The efficient oxidn. of iodide and bromide at the aq. soln.-air interface of the ocean or of sea spray aerosol particles had been suggested to be related to their surface propensity. The ubiquitous presence of org. material at the ocean surface calls for an assessment of the impact of often surface-active org. compds. on the interfacial d. of halide ions. The authors used in situ XPS with a liq. micro-jet to obtain chem. compn. information at aq. soln.-vapor interfaces from mixed aq. solns. contg. bromide or iodide and 1-butanol or butyric acid as org. surfactants. Core level spectra of Br 3d, Na 2s, C 1s and O 1s at ∼160 eV kinetic energy and core level spectra of I 4d and O 1s at ∼400 eV kinetic energy are compared for solns. with 1-butanol and butyric acid as a function of org. concn. A simple model was developed to account for the attenuation of photoelectrons by the aliph. C layer of the surfactants and for changing local d. of bromide and iodide in response to the presence of the surfactants. 1-Butanol increases the interfacial d. of bromide by 25%, while butyric acid reduces it by 40%, both in comparison to the pure aq. halide soln. Qual. similar behavior was obsd. for the case of iodide. Classical mol. dynamics simulations failed to reproduce the details of the response of the halide ions to the presence of the 2 orgs. This is attributed to the lack of correct monovalent ion parameters at low concn. possibly leading to an overestimation of the halide ion concn. at the interface in absence of orgs. Org. surfactants change the electrostatic interactions near the interface with headgroup specific effects. This has implications for halogen activation processes specifically when oxidants interact with halide ions at the aq. soln.-air interfaces of the ocean surface or sea spray aerosol particles.
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    Gladich, I.; Chen, S.; Vazdar, M.; Boucly, A.; Yang, H.; Ammann, M.; Artiglia, L. Surface Propensity of Aqueous Atmospheric Bromine at the Liquid–Gas Interface. J. Phys. Chem. Lett. 2020, 11 (9), 3422– 3429,  DOI: 10.1021/acs.jpclett.0c00633
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    Surface Propensity of Aqueous Atmospheric Bromine at the Liquid-Gas Interface
    Gladich, Ivan; Chen, Shuzhen; Vazdar, Mario; Boucly, Anthony; Yang, Huanyu; Ammann, Markus; Artiglia, Luca
    Journal of Physical Chemistry Letters (2020), 11 (9), 3422-3429CODEN: JPCLCD; ISSN:1948-7185. (American Chemical Society)
    Multiphase reactions of halide ions in aq. solns. exposed to the atm. initiate the formation of mol. halogen compds. in the gas phase. Their photolysis leads to halogen atoms, which are catalytic sinks for ozone, making these processes relevant for the regional and global tropospheric ozone budget. The affinity of halide ions in aq. soln. for the liq.-gas interface, which may influence their reactivity with gaseous species, has been debated. Our study focuses on the surface properties of the bromide ion and its oxidn. products. In situ XPS carried out on a liq. jet combined with classical and first-principles mol. dynamics calcns. was used to investigate the interfacial depth profile of bromide, hypobromite, hypobromous acid, and bromate. The simulated core electron binding energies support the exptl. obsd. values, which follow a correlation with bromine oxidn. state for the anion series. Bromide ions are homogeneously distributed in the soln. Hypobromous acid, a key species in the multiphase cycling of bromine, is the only species showing surface propensity, which suggests a more important role of the interface in multiphase bromine chem. than thought so far.
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    Lee, M.-T.; Brown, M. A.; Kato, S.; Kleibert, A.; Türler, A.; Ammann, M. Competition between Organics and Bromide at the Aqueous Solution–Air Interface as Seen from Ozone Uptake Kinetics and X-ray Photoelectron Spectroscopy. J. Phys. Chem. A 2015, 119 (19), 4600– 4608,  DOI: 10.1021/jp510707s
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    35
    Competition between Organics and Bromide at the Aqueous Solution-Air Interface as Seen from Ozone Uptake Kinetics and X-ray Photoelectron Spectroscopy
    Lee, Ming-Tao; Brown, Matthew A.; Kato, Shunsuke; Kleibert, Armin; Turler, Andreas; Ammann, Markus
    Journal of Physical Chemistry A (2015), 119 (19), 4600-4608CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)
    Reaction of ozone (O3) with NaBr solns. in the presence and absence of citric acid (C6H8O7) under ambient conditions has been studied. Citric acid was used as a proxy for oxidized org. material present at the ocean surface or in sea spray aerosol. On neat NaBr solns., the obsd. kinetics was consistent with bulk reaction-limited uptake, and a second-order rate const. for the reaction of O3 + Br- is 57 ± 10 M-1 s-1. On mixed NaBr-citric acid aq. solns., the uptake kinetics was faster than that predicted by bulk reaction-limited uptake and also faster than expected based on an acid-catalyzed mechanism. XPS spectra on a liq. microjet of the same solns. at 1.0·10-3-1.0·10-4 mbar was used to obtain quant. insight into the interfacial compn. relative to that of the bulk solns. It revealed that the bromide anion was depleted by 30 ± 10% while the sodium cation gets enhanced by 40 ± 20% at the aq. soln.-air interface of a 0.12 M NaBr soln. mixed with 2.5 M citric acid in the bulk, attributed to the role of citric acid as a weak surfactant. Therefore, the enhanced reactivity of bromide solns. obsd. in the presence of citric acid was not necessarily attributable to a surface reaction but could also result from an increased soly. of ozone at higher citric acid concns. Whether the acid-catalyzed chem. may have a larger effect on the surface than in the bulk to offset the effect of bromide depletion also remains open.
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    Ge, X.; Wexler, A. S.; Clegg, S. L. Atmospheric amines – Part I. A review. Atmos. Environ. 2011, 45 (3), 524– 546,  DOI: 10.1016/j.atmosenv.2010.10.012
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    Atmospheric amines - Part I. A review
    Ge, Xinlei; Wexler, Anthony S.; Clegg, Simon L.
    Atmospheric Environment (2011), 45 (3), 524-546CODEN: AENVEQ; ISSN:1352-2310. (Elsevier Ltd.)
    A review presenting the current knowledge of atmospherically-relevant amines with respect to their sources, fluxes, and dynamics, including gas-phase reactions, gas-to-particle conversion, and deposition, is given. Health effects of aliph. and arom. amines are briefly summarized as are the atm. occurrence and reactivity of amino acids and urea. Topics discussed include: atm. sources (anthropogenic [animal husbandry, industry and combustion, composting operations, automobiles, other human activities], natural sources [ocean, biomass burning, vegetation, geol. sources]); estd. global flux and ambient concns.; atm. behavior (gas-phase reactions [oxidn., nitrosamines], gas/particle conversion [particulate amines, acid-base chem.], surface deposition); health effects (aliph. amines and amides, arom. amines); amino acids and urea (atm. occurrence and reactivity); and summary.
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    Ohtani, N.; Ohta, T.; Hosoda, Y.; Yamashita, T. Phase Behavior and Phase-Transfer Catalysis of Tetrabutylammonium Salts. Interface-Mediated Catalysis. Langmuir 2004, 20 (2), 409– 415,  DOI: 10.1021/la035462f
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    Phase Behavior and Phase-Transfer Catalysis of Tetrabutylammonium Salts. Interface-Mediated Catalysis
    Ohtani, Noritaka; Ohta, Tomoaki; Hosoda, Yasuhiro; Yamashita, Tsuyoshi
    Langmuir (2004), 20 (2), 409-415CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)
    The phase behavior and component compn. of the coexisting phases in the tetrabutylammonium bromide (TBABr)/benzene/water/NaBr four-component system were strongly influenced by the temp., TBABr content, and NaBr concn. The phase-transfer catalytic activity of TBABr for the reaction of decyl methanesulfonate with sodium bromide was closely related to the phase behavior. Under O (oil-rich phase) + L (TBABr-rich liq. phase) + W (aq. phase) triphase conditions, the influences of temp. and stirring speed on the phase-transfer catalytic activity were small compared with those under O + W biphase conditions. The addn. of other quaternary salts that were able to form w/o aggregates in the O phase enhanced the TBABr catalytic activity even under O + W conditions. The relationship between phase behavior and catalytic activity of tetrabutylammonium chloride or iodide (TBACl or TBAI) was also examd. The results strongly suggested that the catalysis of TBAX was attributable to the interfacial reactions of TBAX with the substrate. The interface includes the water-oil microinterface formed in the microemulsion-like L phase as well as the bulk water-oil interface.
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    Winter, B.; Weber, R.; Schmidt, P. M.; Hertel, I. V.; Faubel, M.; Vrbka, L.; Jungwirth, P. Molecular Structure of Surface-Active Salt Solutions: Photoelectron Spectroscopy and Molecular Dynamics Simulations of Aqueous Tetrabutylammonium Iodide. J. Phys. Chem. B 2004, 108 (38), 14558– 14564,  DOI: 10.1021/jp0493531
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    Molecular Structure of Surface-Active Salt Solutions: Photoelectron Spectroscopy and Molecular Dynamics Simulations of Aqueous Tetrabutylammonium Iodide
    Winter, Bernd; Weber, Ramona; Schmidt, Philipp M.; Hertel, Ingolf V.; Faubel, Manfred; Vrbka, Lubos; Jungwirth, Pavel
    Journal of Physical Chemistry B (2004), 108 (38), 14558-14564CODEN: JPCBFK; ISSN:1520-6106. (American Chemical Society)
    We report photoelectron measurements and mol. dynamics (MD) simulations with a polarizable force field of surface-active tetrabutylammonium iodide (TBAI) in aq. soln. Photoemission is studied for a photon energy of 100 eV, using a 6-μm-diam. liq. jet. Surfactant activity of the TBAI salt at the soln. surface is proved by a dramatic (×70) increase of the I-(4d) signal, as compared to that of a NaI aq. soln. for identical salt concns. Completion of the segregation monolayer is suggested through the growth of the iodide photoelectron emission signal, as a function of the salt concn. Our expts. reveal identical electron binding energies of iodide in TBAI and NaI aq. solns., which are independent of the salt concn. Zero or very small spectral shifts of any feature, including the low-energy cutoff, suggest that no dipole is formed by TBA+ and I- ion pairs perpendicular to the surface, which is in accord with the simulated ionic d. profiles. Both cations and anions exhibit strong surfactant activity, thus failing to form a strong elec. double layer. While the cations are surface-bound due to hydrophobic interactions, iodide is driven to the vacuum/water interface by its large polarizability. MD simulations also allow characterization of the thermally averaged geometries of the surface-active cations, in particular the orientations of the Bu chains with respect to the water surface.
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    Winter, B.; Weber, R.; Hertel, I. V.; Faubel, M.; Vrbka, L.; Jungwirth, P. Effect of bromide on the interfacial structure of aqueous tetrabutylammonium iodide: Photoelectron spectroscopy and molecular dynamics simulations. Chem. Phys. Lett. 2005, 410 (4), 222– 227,  DOI: 10.1016/j.cplett.2005.05.084
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    Effect of bromide on the interfacial structure of aqueous tetrabutylammonium iodide: Photoelectron spectroscopy and molecular dynamics simulations
    Winter, Bernd; Weber, Ramona; Hertel, Ingolf V.; Faubel, Manfred; Vrbka, Lubos; Jungwirth, Pavel
    Chemical Physics Letters (2005), 410 (4-6), 222-227CODEN: CHPLBC; ISSN:0009-2614. (Elsevier B.V.)
    Solvation of surface-active tetrabutylammonium iodide (TBAI) in liq. water and in NaBr aq. soln. was investigated by VUV photoelectron spectroscopy and by mol. dynamics simulations. The obsd. signal intensity changes in the photoemission spectra are consistent with the varying propensities of the different ions for the soln. interface. While the cations are surface-bound due to hydrophobic interactions, the anions are driven to the vacuum/soln. interface by their large polarizability and size. Iodide is more polarizable, and hence more surface-active than bromide, which explains the relatively small decrease of the iodide photoemission signal when TBAI is dissolved in bromide soln.
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    Karashima, S.; Suzuki, T. Charge-Transfer-to-Solvent Reaction in a Hydrophobic Tetrabutylammonium Iodide Molecular Layer in Aqueous Solution. J. Phys. Chem. B 2019, 123 (17), 3769– 3775,  DOI: 10.1021/acs.jpcb.8b12210
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    Charge-Transfer-to-Solvent Reaction in a Hydrophobic Tetrabutylammonium Iodide Molecular Layer in Aqueous Solution
    Karashima, Shutaro; Suzuki, Toshinori
    Journal of Physical Chemistry B (2019), 123 (17), 3769-3775CODEN: JPCBFK; ISSN:1520-5207. (American Chemical Society)
    We present ultrafast photoelectron spectroscopy of the charge-transfer-to-solvent reaction in a segregated TBAI (tetrabutylammonium iodide) mol. layer in aq. soln. The reaction times and electron binding energies of transient species vary with TBAI concn. from a very low value of 1 × 10-3 mol L-1, which is in contrast to NaI soln. exhibiting no concn. (0.01-1.0 mol L-1) dependence. The result from soft X-ray N(1s) spectroscopy indicates that the photoelectron intensity in TBAI aq. soln. is about 70 times enhanced as compared to that in NH4Cl aq. soln. for an identical salt concn., and TBA+ drags I- to the surface region. At high TBAI concns., electrons released from I- are trapped and held in the TBAI mol. layer owing to electrostatic attraction by TBA+.
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    Watanabe, I.; Takahashi, N.; Tanida, H. Dehydration of iodide segregated by tetraalkylammonium at the air/solution interface studied by photoelectron emission spectroscopy. Chem. Phys. Lett. 1998, 287 (5), 714– 718,  DOI: 10.1016/S0009-2614(98)00231-0
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    Dehydration of iodide segregated by tetraalkylammonium at the air/solution interface studied by photoelectron emission spectroscopy
    Watanabe, Iwao; Takahashi, Naoko; Tanida, Hajime
    Chemical Physics Letters (1998), 287 (5,6), 714-718CODEN: CHPLBC; ISSN:0009-2614. (Elsevier Science B.V.)
    Photoelectron emission spectroscopy was used to detect iodide anion at the aq. soln. surface. The photoelectron emission threshold energies Et for the iodide segregated by tetraalkylammonium cations differ from those for solns. with surface inactive cations. The smaller Et values found for larger alkylammonium salt solns. seem to be due to dehydration of iodide at the surface layer. When tetrabutylammonium is used as the surfactant, the dehydration proceeds in a stepwise way with increasing bulk concn.
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    Sobyra, T. B.; Pliszka, H.; Bertram, T. H.; Nathanson, G. M. Production of Br2 from N2O5 and Br– in Salty and Surfactant-Coated Water Microjets. J. Phys. Chem. A 2019, 123 (41), 8942– 8953,  DOI: 10.1021/acs.jpca.9b04225
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    Production of Br2 from N2O5 and Br- in Salty and Surfactant-Coated Water Microjets
    Sobyra, Thomas B.; Pliszka, Helena; Bertram, Timothy H.; Nathanson, Gilbert M.
    Journal of Physical Chemistry A (2019), 123 (41), 8942-8953CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)
    Gas-liq. scattering expts. are used to investigate the oxidn.-redn. reaction N2O5(g) + 2Br-(aq) → Br2(g) + NO3-(aq) + NO2-(aq), a model for the nighttime absorption of N2O5 into aerosol droplets contg. halide ions. The detection of evapg. Br2 mols. provides our first observation of a gaseous reaction product generated by a water microjet in vacuum. N2O5 mols. are directed at a 35 μm diam. jet of 6 or 8 m LiBr in water at 263 or 240 K, followed by detection of both unreacted N2O5 and product Br2 mols. by velocity-resolved mass spectrometry. The N2O5 reaction probability at near-thermal collision energy is too small to be measured and likely lies below 0.2. However, the evapg. Br2 product can be detected and controlled by the presence of surfactants. The addn. of 0.02 m 1-butanol, which creates ∼40% of a compact monolayer, reduces Br2 prodn. by 35%. Following earlier studies, this redn. may be attributed to surface butanol mols. that block N2O5 entry or alter the near-surface distribution of Br-. Remarkably, addn. of the cationic surfactant tetrabutylammonium bromide (TBABr) at 0.005 m (9% of a monolayer) reduces the Br2 signal by 85%, and a 0.050 m soln. (58% of a monolayer) causes the Br2 signal to disappear entirely. A detailed anal. suggests that TBA+ efficiently suppresses Br2 evapn. because it tightly bonds to the Br3- intermediate formed in the highly concd. Br- soln. and thereby hinders the rapid release and evapn. of Br2.
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  43. 43
    Shaloski, M. A.; Gord, J. R.; Staudt, S.; Quinn, S. L.; Bertram, T. H.; Nathanson, G. M. Reactions of N2O5 with Salty and Surfactant-Coated Glycerol: Interfacial Conversion of Br– to Br2 Mediated by Alkylammonium Cations. J. Phys. Chem. A 2017, 121 (19), 3708– 3719,  DOI: 10.1021/acs.jpca.7b02040
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    43
    Reactions of N2O5 with Salty and Surfactant-Coated Glycerol: Interfacial Conversion of Br- to Br2 Mediated by Alkylammonium Cations
    Shaloski, Michael A.; Gord, Joseph R.; Staudt, Sean; Quinn, Sarah L.; Bertram, Timothy H.; Nathanson, Gilbert M.
    Journal of Physical Chemistry A (2017), 121 (19), 3708-3719CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)
    Gas-liq. scattering and product-yield expts. are used to investigate reactions of N2O5 with glycerol contg. Br- and surfactant ions. N2O5 oxidizes Br- to Br2 for every soln. tested: 2.7 M NaBr, 0.03 M tetrahexylammonium bromide (THABr), 0.03 M THABr + 0.5 M NaBr, 0.03 M THABr + 0.5 M NaCl, 0.03 M THABr + 0.01 M sodium dodecyl sulfate (SDS), and 0.01 M cetyltrimethylammonium bromide (CTABr). N2O5 also reacts with glycerol itself to produce mono- and dinitroglycerin. Surface tension measurements indicate that 0.03 M THABr and 2.7 M NaBr have similar interfacial Br- concns., though their bulk Br- concns. differ by 90-fold. We find that twice as much Br2 is produced in the presence of THA+, implying that the conversion of Br- to Br2 is initiated at the interface, perhaps mediated by the charged, hydrophobic pocket within the surface THA+ cation. The addn. of 0.5 M NaBr, 0.5 M NaCl, or 0.01 M SDS to 0.03 M THABr lowers the Br2 prodn. rate by 23%, 63%, and 67% of the THABr value, resp. When CTA+ is substituted for THA+, Br2 prodn. drops to 12% of the THABr value. The generation of Br2 under such different conditions implies that trace amts. of surface-active alkylammonium ions can catalyze interfacial N2O5 reactions, even when salts and other surfactants are present.
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  44. 44
    Flechsig, U.; Nolting, F.; Fraile Rodriguez, A.; Krempasky, J.; Quitmann, C.; Schmidt, T.; Spielmann, S.; Zimoch, D.; Garrett, R.; Gentle, I.; Nugent, K.; Wilkins, S. Performance Measurements at the SLS SIM Beamline. AIP Conf. Proc. 2009, 1234, 319– 322,  DOI: 10.1063/1.3463200
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    Brown, M. A.; Redondo, A. B.; Jordan, I.; Duyckaerts, N.; Lee, M.-T.; Ammann, M.; Nolting, F.; Kleibert, A.; Huthwelker, T.; Mächler, J.-P.; Birrer, M.; Honegger, J.; Wetter, R.; Wörner, H. J.; Bokhoven, J. A. v. A new endstation at the Swiss Light Source for ultraviolet photoelectron spectroscopy, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy measurements of liquid solutions. Rev. Sci. Instrum. 2013, 84 (7), 073904,  DOI: 10.1063/1.4812786
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    46
    A new endstation at the Swiss Light Source for ultraviolet photoelectron spectroscopy, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy measurements of liquid solutions
    Brown, Matthew A.; Redondo, Amaia Beloqui; Jordan, Inga; Duyckaerts, Nicolas; Lee, Ming-Tao; Ammann, Markus; Nolting, Frithjof; Kleibert, Armin; Huthwelker, Thomas; Maechler, Jean-Pierre; Birrer, Mario; Honegger, Juri; Wetter, Reto; Woerner, Hans Jakob; van Bokhoven, Jeroen A.
    Review of Scientific Instruments (2013), 84 (7), 073904/1-073904/8CODEN: RSINAK; ISSN:0034-6748. (American Institute of Physics)
    A new liq. microjet endstation designed for UV (UPS) and x-ray (XPS) photoelectron, and partial electron yield X-ray absorption (XAS) spectroscopies at the Swiss Light Source is presented. The new endstation, which is based on a Scienta HiPP-2 R4000 electron spectrometer, is the 1st liq. microjet endstation capable of operating in vacuum and in ambient pressures up to the equil. vapor pressure of liq. H2O at room temp. The Scienta HiPP-2 R4000 energy analyzer of this new endstation allows for XPS measurements up to 7000 eV electron kinetic energy that will enable electronic structure measurements of bulk solns. and buried interfaces from liq. microjet samples. The endstation is designed to operate at the soft x-ray SIM beamline and at the tender X-ray Phoenix beamline. The endstation can also be operated using a Scienta 5 K UV He lamp for dedicated UPS measurements at the vapor-liq. interface using either He I or He II α lines. The design concept, 1st results from UPS, soft x-ray XPS, and partial electron yield XAS measurements, and an outlook to the potential of this endstation are presented. (c) 2013 American Institute of Physics.
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  46. 46
    Winter, B.; Weber, R.; Widdra, W.; Dittmar, M.; Faubel, M.; Hertel, I. V. Full Valence Band Photoemission from Liquid Water Using EUV Synchrotron Radiation. J. Phys. Chem. A 2004, 108 (14), 2625– 2632,  DOI: 10.1021/jp030263q
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    Full Valence Band Photoemission from Liquid Water Using EUV Synchrotron Radiation
    Winter, B.; Weber, R.; Widdra, W.; Dittmar, M.; Faubel, M.; Hertel, I. V.
    Journal of Physical Chemistry A (2004), 108 (14), 2625-2632CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)
    The valence band photoelectron spectra of liq. water (H2O and D2O) are studied in the photon energy range from hν = 60 to 120 eV. The expts. use a 6 μm diam. liq.-jet free vacuum surface at the MBI undulator beamline of the synchrotron radiation facility BESSY. Photoelectron emission from all four valence MOs is obsd. In comparison to those of the gas phase, the peaks are significantly broadened and shifted to lower binding energies by about 1.5 eV. This is attributed primarily to the electronic polarization of the solvent mols. around an ionized water mol. Energy shifts, peak broadening, and relative peak intensities for the four MOs differ because of their specific participation in the hydrogen bonding in liq. water. Relative photoionization cross sections for MOs were measured for hν = 60, 80, and 100 eV. The main difference for liq. water, as compared to the gas phase, is the relative intensity decrease of the 1b2 and 3a1 orbitals, reflecting changes of the MOs due to H-bonding.
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    Yeh, J. J.; Lindau, I. Atomic subshell photoionization cross sections and asymmetry parameters: 1 ⩽ Z ⩽ 103. At. Data Nucl. Data Tables 1985, 32 (1), 1– 155,  DOI: 10.1016/0092-640X(85)90016-6
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    Atomic subshell photoionization cross sections and asymmetry parameters: 1 ≤ Z ≤ 103
    Yeh, J. J.; Lindau, I.
    Atomic Data and Nuclear Data Tables (1985), 32 (1), 1-155CODEN: ADNDAT; ISSN:0092-640X.
    At. subshell photoionization cross sections and asymmetry parameters are calcd. with the Hartree-Fock-Slater one-electron central potential model (dipole approxn.) for all elements Z = 1-103. The cross-section results are plotted for all subshells in the energy region 0-1500 eV, and cross sections and asymmetry parameters are tabulated for selected energies in the region 10.2-8047.8 eV. In addn., more detailed graphs are given for the 4d (Z = 39-71) and 5d (Z = 64-100) subshell cross sections in the vicinity of the Cooper min. These data should be particularly useful for work based on spectroscopic investigations of at. subshells using synchrotron radiation and/or discrete line sources.
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    Ottosson, N.; Faubel, M.; Bradforth, S. E.; Jungwirth, P.; Winter, B. Photoelectron spectroscopy of liquid water and aqueous solution: Electron effective attenuation lengths and emission-angle anisotropy. J. Electron Spectrosc. Relat. Phenom. 2010, 177 (2–3), 60– 70,  DOI: 10.1016/j.elspec.2009.08.007
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    49
    Photoelectron spectroscopy of liquid water and aqueous solution: Electron effective attenuation lengths and emission-angle anisotropy
    Ottosson, Niklas; Faubel, Manfred; Bradforth, Stephen E.; Jungwirth, Pavel; Winter, Bernd
    Journal of Electron Spectroscopy and Related Phenomena (2010), 177 (2-3), 60-70CODEN: JESRAW; ISSN:0368-2048. (Elsevier B.V.)
    Photoelectron (PE) spectroscopy measurements from liq. water and from a 4 m NaI aq. soln. are performed using a liq. microjet in combination with soft X-ray synchrotron radiation. From the oxygen 1s PE signal intensity from liq. water, measured as a function of photon energy (up to 1500 eV), we quant. det. relative electron inelastic effective attenuation lengths (EAL) for (photo)electron kinetic energies in the 70-900 eV range. In order to det. the abs. electron escape depths a calibration point is needed, which is not directly accessible by expt. This information can instead be indirectly derived by comparing PE expts. and mol. dynamics (MD) simulations of an aq. soln. interface where d. profiles of water, anions, and cations are distinctively different. We have chosen sodium iodide in water because iodide has a considerable propensity for the soln. surface, whereas the sodium cation is repelled from the surface. By measuring the intensities of photoelectrons emitted from different orbitals of different symmetries from each aq. ion we also evaluate whether gas-phase ionization cross sections and asymmetry parameters can describe the photoemission from ions at and near the aq. soln./vapor interface. We show that gas-phase data reproduce surprisingly well the exptl. observations for hydrated ions as long as the photon energy is sufficiently far above the ionization threshold. Electrons detected at the higher photon energies originate predominantly from deeper layers, suggesting that bulk-soln. electron elastic scattering is relatively weak.
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    Schneider, S. R.; Lakey, P. S. J.; Shiraiwa, M.; Abbatt, J. P. D. Reactive Uptake of Ozone to Simulated Seawater: Evidence for Iodide Depletion. J. Phys. Chem. A 2020, 124 (47), 9844– 9853,  DOI: 10.1021/acs.jpca.0c08917
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    Reactive uptake of ozone to simulated seawater: Evidence for iodide depletion
    Schneider, Stephanie R.; Lakey, Pascale S. J.; Shiraiwa, Manabu; Abbatt, Jonathan P. D.
    Journal of Physical Chemistry A (2020), 124 (47), 9844-9853CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)
    The reaction of ozone with iodide in the ocean is a major ozone dry deposition pathway, as well as an important source of reactive iodine to the marine troposphere. Few prior lab. expts. have been conducted with environmentally relevant ozone mixing ratios and iodide concns., leading to uncertainties in the rate of the reaction under marine boundary layer conditions. As well, there remains disagreement in the literature assessment of the relative contributions of an interfacial reaction via ozone adsorbed to the ocean surface vs. a bulk reaction with dissolved ozone. In this study, we measure the uptake coeff. of ozone over a buffered, pH 8 salt soln. replicating the concns. of iodide, bromide, and chloride in the ocean over an ozone mixing ratio of 60-500 ppb. Due to iodide depletion in the soln., the measured ozone uptake coeff. is dependent on the exposure time of the soln. to ozone and its mixing ratio. A kinetic multilayer model confirms that iodide depletion is occurring not only within ozone's reactodiffusive depth, which is on the order of microns for environmental conditions, but also deeper into the soln. as well. Best model-measurement agreement arises when some degree of nondiffusive mixing is occurring in the soln., transporting iodide from deeper in the soln. to a thin, diffusively mixed upper layer. If such mixing occurs rapidly in the environment, iodide depletion is unlikely to reduce ozone dry deposition rates. Unrealistically high bulk-to-interface partitioning of iodide is required for the model to predict a substantial interfacial component to the reaction, indicating that the Langmuir-Hinshelwood mechanism is not dominant under environmental conditions.
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  50. 50
    Pruyne, J. G.; Lee, M.-T.; Fábri, C.; Beloqui Redondo, A.; Kleibert, A.; Ammann, M.; Brown, M. A.; Krisch, M. J. Liquid–Vapor Interface of Formic Acid Solutions in Salt Water: A Comparison of Macroscopic Surface Tension and Microscopic in Situ X-ray Photoelectron Spectroscopy Measurements. J. Phys. Chem. C 2014, 118 (50), 29350– 29360,  DOI: 10.1021/jp5056039
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    Liquid-vapor interface of formic acid solutions in salt water: A comparison of macroscopic surface tension and microscopic in situ x-ray photoelectron spectroscopy measurement
    Pruyne, Jefferson G.; Lee, Ming-Tao; Fabri, Csaba; Beloqui Redondo, Amaia; Kleibert, Armin; Ammann, Markus; Brown, Matthew A.; Krisch, Maria J.
    Journal of Physical Chemistry C (2014), 118 (50), 29350-29360CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)
    The liq.-vapor interface is difficult to access exptl. but is of interest from a theor. and applied point of view and has particular importance in atm. aerosol chem. Here we examine the liq.-vapor interface for mixts. of water, sodium chloride, and formic acid, an abundant chem. in the atm. We compare the results of surface tension and XPS measurements over a wide range of formic acid concns. Surface tension measurements provide a macroscopic characterization of solns. ranging from 0 to 3 M sodium chloride and from 0 to over 0.5 mol fraction formic acid. Sodium chloride was found to be a weak salting out agent for formic acid with surface excess depending only slightly on salt concn. In situ XPS provides a complementary mol. level description about the liq.-vapor interface. XPS measurements over an exptl. probe depth of 51 Å gave the C 1s to O 1s ratio for both total oxygen and oxygen from water. XPS also provides detailed electronic structure information that is inaccessible by surface tension. D. functional theory calcns. were performed to understand the obsd. shift in C 1s binding energies to lower values with increasing formic acid concn. Part of the exptl. -0.2 eV shift can be assigned to the soln. compn. changing from predominantly monomers of formic acid to a combination of monomers and dimers; however, the lack of an appropriate ref. to calibrate the abs. BE scale at high formic acid mole fraction complicates the interpretation. Our data are consistent with surface tension measurements yielding a significantly more surface sensitive measurement than XPS due to the relatively weak propensity of formic acid for the interface. A simple model allowed us to replicate the XPS results under the assumption that the surface excess was contained in the top four angstroms of soln.
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    Lee, M.-T.; Orlando, F.; Artiglia, L.; Chen, S.; Ammann, M. Chemical Composition and Properties of the Liquid–Vapor Interface of Aqueous C1 to C4 Monofunctional Acid and Alcohol Solutions. J. Phys. Chem. A 2016, 120 (49), 9749– 9758,  DOI: 10.1021/acs.jpca.6b09261
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    Chemical Composition and Properties of the Liquid-Vapor Interface of Aqueous C1 to C4 Monofunctional Acid and Alcohol Solutions
    Lee, Ming-Tao; Orlando, Fabrizio; Artiglia, Luca; Chen, Shuzhen; Ammann, Markus
    Journal of Physical Chemistry A (2016), 120 (49), 9749-9758CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)
    The liq.-vapor interface is playing an important role in aerosol and cloud chem. in cloud droplet activation by aerosol particles and potentially also in ice nucleation. The authors have employed the surface sensitive and chem. selective XPS technique to examine the liq.-vapor interface for mixts. of water and small alcs. or small carboxylic acids (C1 to C4), abundant chems. in the atm. in concn. ranges relevant for cloud chem. or aerosol particles at the point of activation into a cloud droplet. A linear correlation was found between the headgroup carbon 1s core-level signal intensity and the surface excess derived from literature surface tension data with the offset being explained by the bulk contribution to the photoemission signal. The relative interfacial enhancement of the carboxylic acids over the carboxylates at the same bulk concn. is highest (nearly 20) for propionic acid/propionate and still ∼5 for formic acid/formate, also in fair agreement with surface tension measurements. This provides direct spectroscopic evidence for high carboxylic acid concns. at aq. soln.-air interfaces that may be responsible for acid catalyzed chem. under moderately acidic conditions with respect to their bulk aq. phase acidity const. By assessing the ratio of aliph. to headgroup C 1s signal intensities XPS also provides information about the orientation of the mols. The results indicate an increasing orientation of alcs. and neutral acids toward the surface normal as a function of chain length, along with increasing importance of lateral hydrophobic interactions at higher surface coverage. In turn, the carboxylate ions exhibit stronger orientation toward the surface normal than the corresponding neutral acids, likely caused by the stronger hydration of the charged headgroup.
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    Walz, M. M.; Werner, J.; Ekholm, V.; Prisle, N. L.; Öhrwall, G.; Björneholm, O. Alcohols at the aqueous surface: chain length and isomer effects. Phys. Chem. Chem. Phys. 2016, 18 (9), 6648– 6656,  DOI: 10.1039/C5CP06463E
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    Alcohols at the aqueous surface: chain length and isomer effects
    Walz, M.-M.; Werner, J.; Ekholm, V.; Prisle, N. L.; Oehrwall, G.; Bjoerneholm, O.
    Physical Chemistry Chemical Physics (2016), 18 (9), 6648-6656CODEN: PPCPFQ; ISSN:1463-9076. (Royal Society of Chemistry)
    Surface-active org. mols. at the liq.-vapor interface are of great importance in atm. science. Therefore, we studied the surface behavior of alc. isomers with different chain lengths (C4-C6) in aq. soln. with surface- and chem. sensitive XPS, which reveals information about the surface structure on a mol. level. Gibbs free energies of adsorption and surface concns. are detd. from the XPS results using a std. Langmuir adsorption isotherm model. The free energies of adsorption, ranging from around -15 to -19 kJ mol-1 (C4-C6), scale linearly with the no. of carbon atoms within the alcs. with ΔGAds per -CH2- ≈ -2 kJ mol-1. While for the linear alcs., surface concns. lie around 2.4 × 1014 mols. per cm2 at the bulk concns. where monolayers are formed, the studied branched alcs. show lower surface concns. of around 1.6 × 1014 mols. per cm2, both of which are in line with the mol. structure and their orientation at the interface. Interestingly, we find that there is a max. in the surface enrichment factor for linear alcs. at low concns., which is not obsd. for the shorter branched alcs. This is interpreted in terms of a cooperative effect, which we suggest to be the result of more effective van der Waals interactions between the linear alc. alkyl chains at the aq. surface, making it energetically even more favorable to reside at the liq.-vapor interface.
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  53. 53
    Toribio, A. R.; Prisle, N. L.; Wexler, A. S. Statistical Mechanics of Multilayer Sorption: Surface Concentration Modeling and XPS Measurement. J. Phys. Chem. Lett. 2018, 9 (6), 1461– 1464,  DOI: 10.1021/acs.jpclett.8b00332
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    Statistical Mechanics of Multilayer Sorption: Surface Concentration Modeling and XPS Measurement
    Toribio, Anthony R.; Prisle, Noenne L.; Wexler, Anthony S.
    Journal of Physical Chemistry Letters (2018), 9 (6), 1461-1464CODEN: JPCLCD; ISSN:1948-7185. (American Chemical Society)
    The concn. of solute mols. at the surface of a liq. is a factor in heterogeneous reactions, surface tension, and Marangoni-effect-driven surface flows. Increasingly, XPS has enabled surface concns. to be measured. In prior work, the authors employed statistical mechanics to derive expressions for surface tension as a function of solute activity in a binary soln. Here the authors use a Gibbs relation to derive concomitant expressions for surface concn. Surface tension data from the literature for 5 alcs. are used to identify parameters in the surface tension equation. These parameters are then used in the surface concn. equation to predict surface concns. Comparison of these predictions to those measured with XPS shows a factor of 3 difference between measured and predicted surface concns. Potential reasons for the discrepancy are discussed, including lack of surface-bulk equil. in the measurements.
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  54. 54
    Ottosson, N.; Wernersson, E.; Söderström, J.; Pokapanich, W.; Kaufmann, S.; Svensson, S.; Persson, I.; Öhrwall, G.; Björneholm, O. The protonation state of small carboxylic acids at the water surface from photoelectron spectroscopy. Phys. Chem. Chem. Phys. 2011, 13 (26), 12261– 12267,  DOI: 10.1039/c1cp20245f
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    The protonation state of small carboxylic acids at the water surface from photoelectron spectroscopy
    Ottosson, Niklas; Wernersson, Erik; Soederstroem, Johan; Pokapanich, Wandared; Kaufmann, Susanna; Svensson, Svante; Persson, Ingmar; Oehrwall, Gunnar; Bjoerneholm, Olle
    Physical Chemistry Chemical Physics (2011), 13 (26), 12261-12267CODEN: PPCPFQ; ISSN:1463-9076. (Royal Society of Chemistry)
    We report highly surface sensitive core-level photoelectron spectra of small carboxylic acids (formic, acetic and butyric acid) and their resp. carboxylate conjugate base forms (formate, acetate and butyrate) in aq. soln. The relative surface propensity of the carboxylic acids and carboxylates is obtained by monitoring their resp. C1s signal intensities from a soln. in which their bulk concns. are equal. All the acids are found to be enriched at the surface relative to the corresponding carboxylates. By monitoring the PE signals of acetic acid and acetate as a function of total concn., we find that the protonation of acetic acid is nearly complete in the interface layer. This is in agreement with literature surface tension data, from which it is inferred that the acids are enriched at the surface while (sodium) formate and acetate, but not butyrate, are depleted. For butyric acid, we conclude that the carboxylate form co-exists with the acid in the interface layer. The free energy cost of replacing an adsorbed butyric acid mol. with a butyrate ion at 1.0 M concn. is estd. to be >5 kJ mol-1. By comparing concn. dependent surface excess data with the evolution of the corresponding photoemission signals it is furthermore possible to draw conclusions about how the distribution of mols. that contribute to the excess is altered with bulk concn.
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  55. 55
    Bhowmik, D.; Malikova, N.; Mériguet, G.; Bernard, O.; Teixeira, J.; Turq, P. Aqueous solutions of tetraalkylammonium halides: ion hydration, dynamics and ion–ion interactions in light of steric effects. Phys. Chem. Chem. Phys. 2014, 16 (26), 13447– 13457,  DOI: 10.1039/C4CP01164C
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    56
    Aqueous solutions of tetraalkylammonium halides: ion hydration, dynamics and ion-ion interactions in light of steric effects
    Bhowmik, Debsindhu; Malikova, Natalie; Meriguet, Guillaume; Bernard, Olivier; Teixeira, Jose; Turq, Pierre
    Physical Chemistry Chemical Physics (2014), 16 (26), 13447-13457CODEN: PPCPFQ; ISSN:1463-9076. (Royal Society of Chemistry)
    Mol. simulations have allowed us to probe the at. details of aq. solns. of tetramethylammonium (TMA) and tetrabutylammonium (TBA) bromide, across a wide range of concns. (0.5 to 3-4 m). We highlight the space-filling (TMA+) vs. penetrable (TBA+) nature of these polyat. cations and its consequence for ion hydration, ion dynamics and ion-ion interactions. A well-established hydration is seen for both TMA+ and TBA+ throughout the concn. range studied. A clear penetration of water mols., as well as counterions, between the hydrocarbon arms of TBA+, which remain in an extended configuration, is seen. Global rotation of individual TBA+ points towards isolated rather than aggregated ions (from dil. up to 1 m concn.). Only for highly concd. solns., in which inter-penetration of adjacent TBA+s cannot be avoided, does the rotational time increase dramatically. From both structural and dynamic data we conclude that there is absence of hydrophobicity-driven cation-cation aggregation in both TMABr and TBABr solns. studied. The link between these real systems and the theor. predictions for spherical hydrophobic solutes of varying size does not seem straightforward.
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    Shah, A.-u.-H. A.; Ali, K.; Bilal, S. Surface tension, surface excess concentration, enthalpy and entropy of surface formation of aqueous salt solutions. Colloids Surf., A 2013, 417, 183– 190,  DOI: 10.1016/j.colsurfa.2012.10.054
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    Surface tension, surface excess concentration, enthalpy and entropy of surface formation of aqueous salt solutions
    Shah, Anwar-ul-Haq Ali; Ali, Khurshid; Bilal, Salma
    Colloids and Surfaces, A: Physicochemical and Engineering Aspects (2013), 417 (), 183-190CODEN: CPEAEH; ISSN:0927-7757. (Elsevier B.V.)
    Surface tensions of aq. solns. of sodium salts of chloride, bromide and nitrate; potassium salts of chloride, bromide and nitrate; lithium chloride and potassium iodide has been detd. exptl. at different concns. and temps. ranging from 0.10 to 2.00 mol kg-1 and 10-30 °C, resp. Concn. and temp. dependence of the surface tension of the selected salts has been studied for further estn. of surface excess concn., enthalpy and entropy of surface formation. The results show that the surface excess concn. decreases linearly with concn. but remains almost const. with the variations of temp. Similarly the enthalpy of surface formation was obsd. to decrease with concn. but remained almost const. with the change in temp. The entropy of surface formation was found to decrease with concn. in most cases.
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  57. 57
    Ottosson, N.; Vácha, R.; Aziz, E. F.; Pokapanich, W.; Eberhardt, W.; Svensson, S.; Öhrwall, G.; Jungwirth, P.; Björneholm, O.; Winter, B. Large variations in the propensity of aqueous oxychlorine anions for the solution/vapor interface. J. Chem. Phys. 2009, 131 (12), 124706,  DOI: 10.1063/1.3236805
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    Large variations in the propensity of aqueous oxychlorine anions for the solution/vapor interface
    Ottosson, Niklas; Vacha, Robert; Aziz, Emad F.; Pokapanich, Wandared; Eberhardt, Wolfgang; Svensson, Svante; Oehrwall, Gunnar; Jungwirth, Pavel; Bjoerneholm, Olle; Winter, Bernd
    Journal of Chemical Physics (2009), 131 (12), 124706/1-124706/7CODEN: JCPSA6; ISSN:0021-9606. (American Institute of Physics)
    Core-level photoelectron spectroscopy measurements have been performed of aq. solns. of NaCl co-dissolved with NaClOn (n = 1-4). Each species has a distinct Cl 2p electron binding energy, which can be exploited for depth-profiling expts. to study the competition between Cl- and ClOn- anions for residing in the outermost layers of the soln./vapor interface. Strongest propensity for the surface is obsd. for n = 4 (perchlorate), followed by n = 3 (chlorate), n = 2 (chlorite), n = 0 (chloride), and n = 1 (hypochlorite). Mol. dynamics simulations rationalize the greatest surface propensity of the most oxidized anions in terms of their larger size and polarizability. The anomalous behavior of hypochlorite, being less surface-active than chloride, although it is both larger and more polarizable, is suggested to arise from the charge asymmetry over the anion, increasing its efficiency for bulk solvation. (c) 2009 American Institute of Physics.
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  58. 58
    Olivieri, G.; Parry, K. M.; D’Auria, R.; Tobias, D. J.; Brown, M. A. Specific Anion Effects on Na+ Adsorption at the Aqueous Solution–Air Interface: MD Simulations, SESSA Calculations, and Photoelectron Spectroscopy Experiments. J. Phys. Chem. B 2018, 122 (2), 910– 918,  DOI: 10.1021/acs.jpcb.7b06981
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    59
    Specific Anion Effects on Na(+) Adsorption at the Aqueous Solution-Air Interface: MD Simulations, SESSA Calculations, and Photoelectron Spectroscopy Experiments
    Olivieri Giorgia; Brown Matthew A; Parry Krista M; D'Auria Raffaella; Tobias Douglas J
    The journal of physical chemistry. B (2018), 122 (2), 910-918 ISSN:.
    Specific ion effects of the large halide anions have been shown to moderate anion adsorption to the air-water interface (AWI), but little quantitative attention has been paid to the behavior of alkali cations. Here we investigate the concentration and local distribution of sodium (Na(+)) at the AWI in dilute (<1 M) aqueous solutions of NaCl, NaBr, and NaI using a combination of molecular dynamics (MD) and SESSA simulations, and liquid jet ambient pressure photoelectron spectroscopy measurements. We use SESSA to simulate Na 2p photoelectron intensities on the basis of the atom density profiles obtained from MD simulations, and we compare the simulation results with photoelectron spectroscopy experiments to evaluate the performance of a nonpolarizable force field model versus that of an induced dipole polarizable one. Our results show that the nonpolarizable force model developed by Horinek and co-workers (Chem. Phys. Lett. 2009, 479, 173-183) accurately predicts the local concentration and distribution of Na(+) near the AWI for all three electrolytes, whereas the polarizable model does not. To our knowledge, this is the first interface-specific spectroscopic validation of a MD force field. The molecular origins of the unique Na(+) distributions for the three electrolytes are analyzed on the basis of electrostatic arguments, and shown to arise from an indirect anion effect wherein the identity of the anion affects the strength of the attractive Na(+)-H2O electrostatic interaction. Finally, we use the photoelectron spectroscopy results to constrain the range of inelastic mean free paths (IMFPs) for the three electrolyte solutions used in the SESSA simulations that are able to reproduce the experimental intensities. Our results suggest that earlier estimates of IMFPs for aqueous solutions are likely too high.
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    Eschen, F.; Heyerhoff, M.; Morgner, H.; Vogt, J. The concentration-depth profile at the surface of a solution of tetrabutylammonium iodide in formamide, based on angle-resolved photoelectron spectroscopy. J. Phys.: Condens. Matter 1995, 7 (10), 1961– 1978,  DOI: 10.1088/0953-8984/7/10/006
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    The concentration-depth profile at the surface of a solution of tetrabutylammonium iodide in formamide, based on angle-resolved photoelectron spectroscopy
    Eschen, F.; Heyerhoff, M.; Morgner, H.; Vogt, J.
    Journal of Physics: Condensed Matter (1995), 7 (10), 1961-78CODEN: JCOMEL; ISSN:0953-8984. (Institute of Physics Publishing)
    We have investigated a soln. of tetrabutylammonium iodide (TBAI) in the polar solvent formamide (FA) using angle-resolved photoelectron spectroscopy at the Berlin Electron Storage Ring for Synchrotron Radiation (BESSY). The concn. was set to 0.5 molality. We have evaluated the signals from C 1s pertaining to TBAI and FA sep., varying the photon energy between 310 and 540 eV as well as the e-emission angle with respect to the surface normal. The combination of these data with earlier results from ARXPS obtained by Siegbahn and co-workers allowed us to establish a concn.-depth profile of the surface-active salt TBAI. For this purpose we have employed a new theor. formulation and developed a new elaborate fitting program based on a genetic algorithm. The concn. of the salt could be followed down to a depth of about 45 Å below the surface. Cross sections for the inelastic energy loss of electrons in the liq. could be established as a function of electron energy. Comparison with conventional surface tension measurements allowed us to derive abs. values for the cross sections.
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    Bergersen, H.; Marinho, R. R. T.; Pokapanich, W.; Lindblad, A.; Björneholm, O.; Sæthre, L. J.; Öhrwall, G. A photoelectron spectroscopic study of aqueous tetrabutylammonium iodide. J. Phys.: Condens. Matter 2007, 19 (32), 326101,  DOI: 10.1088/0953-8984/19/32/326101
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    A photoelectron spectroscopic study of aqueous tetrabutylammonium iodide
    Bergersen, H.; Marinho, R. R. T.; Pokapanich, W.; Lindblad, A.; Bjoerneholm, O.; Saethre, L. J.; Oehrwall, G.
    Journal of Physics: Condensed Matter (2007), 19 (32), 326101/1-326101/9CODEN: JCOMEL; ISSN:0953-8984. (Institute of Physics Publishing)
    Photoelectron spectra of Bu4NI (TBAI) dissolved in H2O were recorded using a novel exptl. set-up, which enables photoelectron spectroscopy of volatile liqs. The set-up is described. Ionization energies are reported for I- 5p, I- 4d, C 1s and N 1s. The C 1s spectrum shows evidence of inelastic scattering of the photoelectrons, that differs from the case of TBAI in formamide.
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    Woods, E.; Konys, C. A.; Rossi, S. R. Photoemission of Iodide from Aqueous Aerosol Particle Surfaces. J. Phys. Chem. A 2019, 123 (13), 2901– 2907,  DOI: 10.1021/acs.jpca.8b12323
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    Photoemission of iodide from aqueous aerosol particle surfaces
    Woods, Ephraim; Konys, Casey A.; Rossi, Sean R.
    Journal of Physical Chemistry A (2019), 123 (13), 2901-2907CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)
    The photoemission of iodide from aq. aerosol particle surfaces measures the surface concn. of iodide in predominantly supersatd. NaCl aerosol particles. Using the Langmuir model to describe the adsorption to the surface of aq. iodide anions, the std. Gibbs free energy of adsorption is -15 kJ/mol in these systems. The presence of charged surfactants on the particle surfaces changes the adsorption behavior of iodide. The addn. of sodium docecylsulfate (SDS) reduces the coverage of iodide, consistent with a competitive adsorption scenario. For surfaces coated with C12-, C14-, or C16-trimethylammonium chloride, the addn. of iodide results in the formation of iodide-surfactant ion pairs at the surface with enhanced photoemission. The adsorption free energy for iodide in these systems is -21 kJ/mol. The results demonstrate the surface enhancement of iodide in supersatd., atmospherically relevant conditions and demonstrate important differences between single-salt solns. and mixts. in the limit of high concn.
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    Zhao, X.; Nathanson, G. M.; Andersson, G. G. Experimental Depth Profiles of Surfactants, Ions, and Solvent at the Angstrom Scale: Studies of Cationic and Anionic Surfactants and their Salting Out. J. Phys. Chem. B 2020, 124 (11), 2218– 2229,  DOI: 10.1021/acs.jpcb.9b11686
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    Experimental Depth Profiles of Surfactants, Ions, and Solvent at the Angstrom Scale: Studies of Cationic and Anionic Surfactants and Their Salting Out
    Zhao, Xianyuan; Nathanson, Gilbert M.; Andersson, Gunther G.
    Journal of Physical Chemistry B (2020), 124 (11), 2218-2229CODEN: JPCBFK; ISSN:1520-5207. (American Chemical Society)
    Neutral impact ion scattering spectroscopy (NICISS) is used to measure the depth profiles of ionic surfactants, counterions, and solvent mols. on the angstrom scale. The chosen surfactants are 0.010 m tetrahexylammonium bromide (THA+/Br-) and 0.0050 m sodium dodecyl sulfate (Na+/DS-) in the absence and presence of 0.30 m NaBr in liq. glycerol. NICISS dets. the depth profiles of the elements C, O, Na, S, and Br through the loss in energy of 5 keV He atoms that travel into and out of the liq., which is then converted into depth. In the absence of NaBr, we find that THA+ and its Br- counterion segregate together because of charge attraction, forming a narrow double layer that is 10 Å wide and 150 times more concd. than in the bulk. With the addn. of NaBr, THA+ is "salted out" to the surface, increasing the interfacial Br- concn. by 3-fold and spreading the anions over a ∼30 Å depth. Added NaBr similarly increases the interfacial concn. of DS- ions and broadens their positions. Conversely, the dissolved Br- ions are significantly depleted over a depth of 0-40 Å from the surface because of charge repulsion from DS- ions within the interfacial region. These different interfacial Br- propensities correlate with previously measured gas-liq. reactivities: gaseous Cl2 readily reacts with Br- ions in the presence of THA+ but drops 70-fold in the presence of DS-, demonstrating that surfactant headgroup charge controls the reactivity of Br- through changes in its depth profile.
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    Walz, M. M.; Caleman, C.; Werner, J.; Ekholm, V.; Lundberg, D.; Prisle, N. L.; Ohrwall, G.; Bjorneholm, O. Surface behavior of amphiphiles in aqueous solution: a comparison between different pentanol isomers. Phys. Chem. Chem. Phys. 2015, 17 (21), 14036– 14044,  DOI: 10.1039/C5CP01870F
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    Surface behavior of amphiphiles in aqueous solution: a comparison between different pentanol isomers
    Walz, M.-M.; Caleman, C.; Werner, J.; Ekholm, V.; Lundberg, D.; Prisle, N. L.; Oehrwall, G.; Bjoerneholm, O.
    Physical Chemistry Chemical Physics (2015), 17 (21), 14036-14044CODEN: PPCPFQ; ISSN:1463-9076. (Royal Society of Chemistry)
    Surface-active oxygenated amphiphilic isomers (1- and 3-pentanol) have been compared at the aq. surface with surface- and chem. sensitive XPS, which reveals information about the surface structure on a mol. level. The exptl. data are complemented with mol. dynamics (MD) simulations. A concn.-dependent orientation and solvation of the amphiphiles at the aq. surface is obsd. At bulk concns. as low as around 100 mM, a monolayer starts to form for both isomers, with the hydroxyl groups pointing towards the bulk water and the alkyl chains pointing towards the vacuum. The monolayer (ML) packing d. of 3-pentanol is approx. 70% of the one obsd. for 1-pentanol, with a molar surface concn. that is approx. 90 times higher than the bulk concn. for both mols. The mol. area at ML coverage (≈ 100 mM) was calcd. to be around 32 ± 2 Å2 per mol. for 1-pentanol and around 46 ± 2 Å2 per mol. for 3-pentanol, which results in a higher surface concn. (mols. per cm2) for the linear isomer. In general we conclude therefore that isomers - with comparable surface activities - that have smaller mol. areas will be more abundant at the interface in comparison to isomers with larger mol. areas, which might be of crucial importance for the understanding of key properties of aerosols, such as evapn. and uptake capabilities as well as their reactivity.
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    Ghosal, S.; Brown, M. A.; Bluhm, H.; Krisch, M. J.; Salmeron, M.; Jungwirth, P.; Hemminger, J. C. Ion Partitioning at the Liquid/Vapor Interface of a Multicomponent Alkali Halide Solution: A Model for Aqueous Sea Salt Aerosols. J. Phys. Chem. A 2008, 112 (48), 12378– 12384,  DOI: 10.1021/jp805490f
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    Ion Partitioning at the Liquid/Vapor Interface of a Multicomponent Alkali Halide Solution: A Model for Aqueous Sea Salt Aerosols
    Ghosal, Sutapa; Brown, Matthew A.; Bluhm, Hendrik; Krisch, Maria J.; Salmeron, Miquel; Jungwirth, Pavel; Hemminger, John C.
    Journal of Physical Chemistry A (2008), 112 (48), 12378-12384CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)
    The chem. of Br- species assocd. with sea salt ice and aerosols has been implicated in the episodes of ozone depletion reported at Arctic sunrise. However, Br- is only a minor component in sea salt, which has a Br-/Cl- molar ratio of ∼0.0015. Sea salt is a complex mixt. of many different species, with NaCl as the primary component. In recent years exptl. and theor. studies have reported enhancement of the large, more polarizable halide ion at the liq./vapor interface of corresponding aq. alkali halide solns. The proposed enhancement is likely to influence the availability of sea salt Br- for heterogeneous reactions such as those involved in the ozone depletion episodes. We report here ambient pressure XPS studies and mol. dynamics simulations showing direct evidence of Br- enhancement at the interface of an aq. NaCl soln. doped with bromide. The expts. were carried out on samples with Br-/Cl- ratios 0.1-10%, the latter being also the ratio for which simulations were carried out. This is the 1st direct measurement of interfacial enhancement of Br- in a multicomponent soln. with particular relevance to sea salt chem.
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    Toivola, M.; Prisle, N. L.; Elm, J.; Waxman, E. M.; Volkamer, R.; Kurtén, T. Can COSMOTherm Predict a Salting in Effect?. J. Phys. Chem. A 2017, 121 (33), 6288– 6295,  DOI: 10.1021/acs.jpca.7b04847
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    Can COSMOTherm Predict a Salting in Effect?
    Toivola, Martta; Prisle, Noenne L.; Elm, Jonas; Waxman, Eleanor M.; Volkamer, Rainer; Kurten, Theo
    Journal of Physical Chemistry A (2017), 121 (33), 6288-6295CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)
    We have used COSMO-RS, a method combining quantum chem. with statistical thermodn., to compute Setschenow consts. (KS) for a large array of org. solutes and salts. These comprise both atmospherically relevant solute-salt combinations, as well as systems for which exptl. data are available. In agreement with previous studies on single salts, the Setschenow consts. predicted by COSMO-RS (as implemented in the COSMOTherm program) are generally too large compared to expts. COSMOTherm overpredicts salting out (pos. KS), and/or underpredicts salting in (neg. KS). For ammonium and sodium salts, KS values are larger for oxalates and sulfates, and smaller for chlorides and bromides. For chloride and bromide salts, KS values usually increase with decreasing size of the cation, along the series Pr4N+ < Et4N+ < Me4N+ ≤ Na+ ≈ NH4+. Of the atmospherically relevant systems studied, salting in is predicted only for oxalic acid in sodium and ammonium oxalate, and sodium sulfate, solns. COSMOTherm was thus unable to replicate the exptl. obsd. salting in of glyoxal in sulfate solns., likely due to the overestimation of salting out effects. By contrast, COSMOTherm does qual. predict the exptl. obsd. salting in of multiple org. solutes in solns. of alkylaminium salts.
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    Endo, S.; Pfennigsdorff, A.; Goss, K.-U. Salting-Out Effect in Aqueous NaCl Solutions: Trends with Size and Polarity of Solute Molecules. Environ. Sci. Technol. 2012, 46 (3), 1496– 1503,  DOI: 10.1021/es203183z
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    Salting-Out Effect in Aqueous NaCl Solutions: Trends with Size and Polarity of Solute Molecules
    Endo, Satoshi; Pfennigsdorff, Andrea; Goss, Kai-Uwe
    Environmental Science & Technology (2012), 46 (3), 1496-1503CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
    Salting-out in aq. NaCl solns. is relevant for the environmental behavior of org. contaminants. Setschenow (or salting-out) coeffs. (Ks [M-1]) for 43 diverse neutral compds. in NaCl solns. were measured using a shared headspace passive dosing method and a negligible depletion solid phase microextn. technique. The results were used to calibrate and evaluate estn. models for Ks. The molar volume of the solute correlated only moderately with Ks (R2 =0.49, SD =0.052). The polyparameter linear free energy relation (pp-LFER) model that uses 5 compd. descriptors resulted in a more accurate fit to our data (R2 =0.83, SD =0.031). The pp-LFER anal. revealed that Na+ and Cl- in aq. solns. increase the cavity formation energy cost and the polar interaction energies toward neutral org. solutes. Accordingly, the salting-out effect increases with the size and decreases with the polarity of the solute mol. COSMO-RS, a quantum mechanics-based fully predictive model, generally overpredicted the exptl. Ks, but the predicted values were moderately correlated with the exptl. values (R2 =0.66, SD =0.042). Literature data (n =93) were predicted by the calibrated pp-LFER and COSMO-RS models with root mean squared errors of 0.047 and 0.050, resp. This study offers prediction models to est. Ks, allowing implementation of the salting-out effect in contaminant fate models, linkage of various partition coeffs. (such as air-water, sediment-water, and extn. phase-water partition coeffs.) measured for freshwater and seawater, and estn. of enhancement of extn. efficiency in anal. procedures.
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    Krisch, M. J.; D’Auria, R.; Brown, M. A.; Tobias, D. J.; Hemminger, C.; Ammann, M.; Starr, D. E.; Bluhm, H. The Effect of an Organic Surfactant on the Liquid–Vapor Interface of an Electrolyte Solution. J. Phys. Chem. C 2007, 111 (36), 13497– 13509,  DOI: 10.1021/jp073078b
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    The Effect of an Organic Surfactant on the Liquid-Vapor Interface of an Electrolyte Solution
    Krisch, Maria J.; D'Auria, Raffaella; Brown, Matthew A.; Tobias, Douglas J.; Hemminger, John C.; Ammann, Markus; Starr, David E.; Bluhm, Hendrik
    Journal of Physical Chemistry C (2007), 111 (36), 13497-13509CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)
    Insight into ion behavior at mixed org./aq. liq. surfaces is crucial for understanding the chem. of atm. aerosols, which frequently contain mixts. of water, electrolytes, and orgs. The addn. of 1-butanol to an aq. potassium iodide soln. modifies the interfacial profile of ions at the liq.-vapor interface. Our expts. probe at. compn. at the liq. surface with ambient pressure XPS. Photoelectron kinetic energies are varied to produce a depth profile of the liq.-vapor interface. Mol. dynamics simulations of butanol in an aq. electrolyte soln. are used to develop a detailed understanding of the ion-solvent interactions in the interfacial region. Our previous work on pure aq. salt solns. obsd. substantial ion concns. at the liq.-vapor interface and an increased anion/cation ratio at the interface. A question has arisen as to whether covering the surface with an org. monolayer might change or suppress the interfacial ion concns. We observe that the direct interaction of both the cation and the anion with the butanol leads to changes in the ion concns. in the region of the liq. interface. Substantial ion concns. are still obsd. in the interfacial region in the presence of butanol. However, we do find that the presence of the butanol reduces the previously obsd. anion/cation sepn. in the interfacial region.
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    Sawada, K.; Takahashi, E.; Horie, T.; Satoh, K. Solvent Effects on Ion-Pair Distribution and Dimerization of Tetraalkylammonium Salts. Monatsh. Chem. 2001, 132 (11), 1439– 1450,  DOI: 10.1007/s007060170026
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    Solvent effects on ion-pair distribution and dimerization of tetraalkylammonium salts
    Sawada, Kiyoshi; Takahashi, Eiji; Horie, Tomokazu; Satoh, Keiichi
    Monatshefte fuer Chemie (2001), 132 (11), 1439-1450CODEN: MOCMB7; ISSN:0026-9247. (Springer-Verlag Wien)
    The distribution of tetraalkylammonium ions (CnH2n+1)4N+ (R+, TAAn+, n = 4-7) with picrate ion (pic-) and inorg. anions X-, (Cl-, Br-, ClO4-), into various inert org. solvents was studied at 25.0 °C. The distribution data were analyzed by taking into consideration the distribution of ion pairs, R+·X-, and the dimerization of the ion pairs, (R+·X-)2, in the org. phase. The ion-pair, distribution const., Kdist, increases with increasing chain length of the tetralkylammonium ion and with increasing ionic radius of the anion. The values of Kdist show a good correlation with the ET value of solvent, i.e. the solvation ability with respect to the anion, and smoothly increase with increasing ET. The effect of the solvent on the dimerization consts., Kdim, is markedly different between the ion pairs of picrate ion and inorg. anions. In the case of picrate, Kdim significantly decreases with decreasing length of the alkyl chain of the tetraalkylammonium ion, but hardly changes by changing the solvent. On the other hand, in the case of ion pairs of inorg. anions the value of Kdim decreases with decreasing ET and is almost const. for all anions. These results were reasonably explained by the difference of the solvation of the anion moieties of the monomeric and dimeric ion pairs.
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    Tomar, P. A.; Kolhapurkar, R. R.; Dagade, D. H.; Patil, K. J. Equilibrium Constant Studies for Complexation between Ammonium Ions and 18-Crown-6 in Aqueous Solutions at 298.15 K. J. Solution Chem. 2007, 36 (2), 193– 209,  DOI: 10.1007/s10953-006-9102-5
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  • Abstract

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    Figure 1

    Figure 1. (a) O 1s and (b) Br 3d photoelectron spectra of 0.1 M TBA-Br and 0.1 M NaBr aqueous solutions at photon energies of 900 and 450 eV, respectively. (c) O 1s and (d) Br 3d photoelectron spectra of 0.1 M TBA-Br and 0.1 M NaBr aqueous solutions in the presence of O3, at photon energies of 900 and 450 eV, respectively. The spectra within each panel share the y-axis scale.

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    Figure 2

    Figure 2. (a)nMeasured and parametrized uptake coefficients of O3 as a function of gas phase O3 concentration for 0.1 M NaBr (black), 0.1 M NaBr/0.55 M NaCl (gray), 0.1 M TBA-Br (red), and 0.1 M TBA-Br/0.55 M NaCl (dark-blue) in the aqueous solutions. (b) Uptake coefficient of O3 at 36 ppb compared with the measured [Br·OOO]−/O intensity ratio for three different aqueous solutions.

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    Figure 3

    Figure 3. Scheme of the TBA covered interface used for the attenuation model. The reference level 0 for the depth scale (z) denotes the position where the water density drops to zero and is put just above the N-group of TBA, such that the aliphatic carbons of three of the butyl chains reside at – d1 < z < 0 (on the vacuum side). The aliphatic carbons of the fourth chain are within z < d2. The layer 0 < z < Δ is representing the layer in which the concentration of bromide is deviating from its bulk value, nb,Br, by the factor f. Red, blue, and dark and light gray spheres denote bromide, nitrogen, carbon, and hydrogen atoms, respectively.

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    Figure 4

    Figure 4. (a) Normalized methyl carbon C 1s and (b) liquid water O 1s photoemission intensity as a function of TBA-Br concentration for four different TBA-Br concentrations, measured at photon energies of 660 and 900 eV, respectively. (c) Normalized C/O intensity ratio as a function of TBA-Br concentration from the data in (a) and (b). Normalization as described in the text. Symbols present the experimental data, and the lines are the calculated quantities returned by the attenuation model described in the text.

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    Figure 5

    Figure 5. (a) Br 3d, (b) O 1s, (c) C 1s, (d) N 1s, and (e) Cl 2p photoemission spectra of aqueous solutions taken at a kinetic energy of 155 eV for 0.1 M TBA-Br (red), 0.1 M TBA-Br/0.55 M NaCl (dark blue), 0.1 M TBA-Br/0.1 M NaBr (pink), and 0.1 M TBA-Br/0.1 M NaBr/0.55 M NaCl (light blue), normalized to the the number of sweeps. Lines with symbols represent the measured data, and the shaded areas represent the fitted contributions of the corresponding core levels.

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    Figure 6

    Figure 6. Uptake coefficient of O3 at 36 ppb compared with the measured Br–/O intensity ratio (lower x-axis, green) and calculated Br– interfacial concentration (upper x-axis, pink) for four different aqueous solutions.

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      5
      Active and widespread halogen chemistry in the tropical and subtropical free troposphere
      Wang, Siyuan; Schmidt, Johan A.; Baidar, Sunil; Coburn, Sean; Dix, Barbara; Koenig, Theodore K.; Apel, Eric; Bowdalo, Dene; Campos, Teresa L.; Eloranta, Ed; Evans, Mathew J.; DiGangi, Joshua P.; Zondlo, Mark A.; Gao, Ru-Shan; Haggerty, Julie A.; Hall, Samuel R.; Hornbrook, Rebecca S.; Jacob, Daniel; Morley, Bruce; Pierce, Bradley; Reeves, Mike; Romashkin, Pavel; ter Schure, Arnout; Volkamer, Rainer
      Proceedings of the National Academy of Sciences of the United States of America (2015), 112 (30), 9281-9286CODEN: PNASA6; ISSN:0027-8424. (National Academy of Sciences)
      Halogens in the troposphere are increasingly recognized as playing an important role for atm. chem., and possibly climate. Bromine and iodine react catalytically to destroy ozone (O3), oxidize mercury, and modify oxidative capacity that is relevant for the lifetime of greenhouse gases. Most of the tropospheric O3 and methane (CH4) loss occurs at tropical latitudes. Here we report simultaneous measurements of vertical profiles of bromine oxide (BrO) and iodine oxide (IO) in the tropical and subtropical free troposphere (10°N to 40°S), and show that these halogens are responsible for 34% of the column-integrated loss of tropospheric O3. The obsd. BrO concns. increase strongly with altitude (∼3.4 pptv at 13.5 km), and are 2-4 times higher than predicted in the tropical free troposphere. BrO resembles model predictions more closely in stratospheric air. The largest model low bias is obsd. in the lower tropical transition layer (TTL) over the tropical eastern Pacific Ocean, and may reflect a missing inorg. bromine source supplying an addnl. 2.5-6.4 pptv total inorg. bromine (Bry), or model overestimated Bry wet scavenging. Our results highlight the importance of heterogeneous chem. on ice clouds, and imply an addnl. Bry source from the debromination of sea salt residue in the lower TTL. The obsd. levels of bromine oxidize mercury up to 3.5 times faster than models predict, possibly increasing mercury deposition to the ocean. The halogen-catalyzed loss of tropospheric O3 needs to be considered when estg. past and future ozone radiative effects.
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    6. 6
      Simpson, W. R.; Brown, S. S.; Saiz-Lopez, A.; Thornton, J. A.; von Glasow, R. Tropospheric Halogen Chemistry: Sources, Cycling, and Impacts. Chem. Rev. 2015, 115 (10), 4035– 4062,  DOI: 10.1021/cr5006638
      6
      Tropospheric Halogen Chemistry: Sources, Cycling, and Impacts
      Simpson, William R.; Brown, Steven S.; Saiz-Lopez, Alfonso; Thornton, Joel A.; von Glasow, Roland
      Chemical Reviews (Washington, DC, United States) (2015), 115 (10), 4035-4062CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)
      A review concerning tropospheric reactive halogen chem., i.e., sources, cycling, and impacts, is given. Topics discussed include: introduction/history; synthesis of halogen chem. (halogen radical reactions, halogen sources and observations); recent advances in tropospheric halogen chem. (polar regions, marine boundary layer, NOx pollution-related halogen chem., regional and global halogen chem.); impacts of halogen chem. (O3 and troposphere oxidizing capacity, polar, marine boundary layer, polluted regions); future research needs; and conclusions.
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    7. 7
      Koenig, T. K.; Baidar, S.; Campuzano-Jost, P.; Cuevas, C. A.; Dix, B.; Fernandez, R. P.; Guo, H.; Hall, S. R.; Kinnison, D.; Nault, B. A.; Ullmann, K.; Jimenez, J. L.; Saiz-Lopez, A.; Volkamer, R. Quantitative detection of iodine in the stratosphere. Proc. Natl. Acad. Sci. U. S. A. 2020, 117 (4), 1860– 1866,  DOI: 10.1073/pnas.1916828117
      7
      Quantitative detection of iodine in the stratosphere
      Koenig, Theodore K.; Baidar, Sunil; Campuzano-Jost, Pedro; Cuevas, Carlos A.; Dix, Barbara; Fernandez, Rafael P.; Guo, Hongyu; Hall, Samuel R.; Kinnison, Douglas; Nault, Benjamin A.; Ullmann, Kirk; Jimenez, Jose L.; Saiz-Lopez, Alfonso; Volkamer, Rainer
      Proceedings of the National Academy of Sciences of the United States of America (2020), 117 (4), 1860-1866CODEN: PNASA6; ISSN:0027-8424. (National Academy of Sciences)
      Oceanic emissions of iodine destroy ozone, modify oxidative capacity, and can form new particles in the troposphere. However, the impact of iodine in the stratosphere is highly uncertain due to the lack of previous quant. measurements. Here, we report quant. measurements of iodine monoxide radicals and particulate iodine (Iy,part) from aircraft in the stratosphere. These measurements support that 0.77 ± 0.10 parts per trillion by vol. (pptv) total inorg. iodine (Iy) is injected to the stratosphere. These high Iy amts. are indicative of active iodine recycling on ice in the upper troposphere (UT), support the upper end of recent Iy ests. (0 to 0.8 pptv) by the World Meteorol. Organization, and are incompatible with zero stratospheric iodine injection. Gas-phase iodine (Iy,gas) in the UT (0.67 ± 0.09 pptv) converts to Iy,part sharply near the tropopause. In the stratosphere, IO radicals remain detectable (0.06 ± 0.03 pptv), indicating persistent Iy,part recycling back to Iy,gas as a result of active multiphase chem. At the obsd. levels, iodine is responsible for 32% of the halogen-induced ozone loss (bromine 40%, chlorine 28%), due primarily to previously unconsidered heterogeneous chem. Anthropogenic (pollution) ozone has increased iodine emissions since preindustrial times (∼factor of 3 since 1950) and could be partly responsible for the continued decrease of ozone in the lower stratosphere. Increasing iodine emissions have implications for ozone radiative forcing and possibly new particle formation near the tropopause.
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    8. 8
      Abbatt, J. P. D.; Waschewsky, G. C. G. Heterogeneous Interactions of HOBr, HNO3, O3, and NO2 with Deliquescent NaCl Aerosols at Room Temperature. J. Phys. Chem. A 1998, 102 (21), 3719– 3725,  DOI: 10.1021/jp980932d
      8
      Heterogeneous Interactions of HOBr, HNO3, O3, and NO2 with Deliquescent NaCl Aerosols at Room Temperature
      Abbatt, J. P. D.; Waschewsky, G. C. G.
      Journal of Physical Chemistry A (1998), 102 (21), 3719-3725CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)
      To better quantify the rates at which key trace gases interact with sea-salt aerosols, the kinetics of uptake of HOBr, HNO3, O3, and NO2 by deliquescent NaCl aerosols at 75% relative humidity (RH) and room temp. have been studied using an aerosol kinetics flow tube technique. Results for HOBr indicate that the uptake coeff. (γ) is larger than 0.2 for highly acidic aerosols at pH 0.3 and for aerosols that have been buffered to pH 7.2 using a 0.25 M NaH2PO4/Na2HPO4 buffer. For unbuffered NaCl aerosols, the HOBr uptake coeff. due to reaction is less than 1.5 × 10-3. For HNO3, the uptake coeff. on unbuffered, NaCl aerosols is greater than 0.2, being driven by the very high soly. of HNO3 in aq. salt solns. Both NO2 and O3 show low reactivity on pH neutral aerosols with upper limits to the uptake coeffs. of 10-4. With acidic aerosols, slight O3 loss occurs either on the walls of the flow tube or on the aerosols, giving rise to Cl2. These expts. are the first reported kinetics studies of the loss of HOBr, HNO3, and O3 on aq. NaCl solns., and they imply that gas-phase diffusion, and not reaction kinetics, dets. the mass-transfer rates of gas-phase HNO3 and HOBr to marine aerosols in the boundary layer. Also, the HOBr results support modeling studies which have proposed that HOBr uptake initiates autocatalytic release of bromide from sea-salt aerosols.
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    9. 9
      Simpson, W. R.; von Glasow, R.; Riedel, K.; Anderson, P.; Ariya, P.; Bottenheim, J.; Burrows, J.; Carpenter, L. J.; Frieß, U.; Goodsite, M. E.; Heard, D.; Hutterli, M.; Jacobi, H. W.; Kaleschke, L.; Neff, B.; Plane, J.; Platt, U.; Richter, A.; Roscoe, H.; Sander, R.; Shepson, P.; Sodeau, J.; Steffen, A.; Wagner, T.; Wolff, E. Halogens and their role in polar boundary-layer ozone depletion. Atmos. Chem. Phys. 2007, 7 (16), 4375– 4418,  DOI: 10.5194/acp-7-4375-2007
      9
      Halogens and their role in polar boundary-layer ozone depletion
      Simpson, W. R.; von Glasow, R.; Riedel, K.; Anderson, P.; Ariya, P.; Bottenheim, J.; Burrows, J.; Carpenter, L. J.; Friess, U.; Goodsite, M. E.; Heard, D.; Hutterli, M.; Jacobi, H.-W.; Kaleschke, L.; Neff, B.; Plane, J.; Platt, U.; Richter, A.; Roscoe, H.; Sander, R.; Shepson, P.; Sodeau, J.; Steffen, A.; Wagner, T.; Wolff, E.
      Atmospheric Chemistry and Physics (2007), 7 (16), 4375-4418CODEN: ACPTCE; ISSN:1680-7316. (Copernicus Publications)
      A review. During springtime in the polar regions, unique photochem. converts inert halide salt ions (e.g. Br-) into reactive halogen species (e.g. Br atoms and BrO) that deplete ozone in the boundary layer to near zero levels. Since their discovery in the late 1980s, research on ozone depletion events (ODEs) has made great advances; however many key processes remain poorly understood. In this article we history, chem., dependence on environmental conditions, and impacts of ODEs are reviewed. This research has shown the central role of bromine photochem., but how salts are transported from the ocean and are oxidized to become reactive halogen species in the air is still not fully understood. Halogens other than bromine (chlorine and iodine) are also activated through incompletely understood mechanisms that are probably coupled to bromine chem. The main consequence of halogen activation is chem. destruction of ozone, which removes the primary precursor of atm. oxidn., and generation of reactive halogen atoms/oxides that become the primary oxidizing species. The different reactivity of halogens as compared to OH and ozone has broad impacts on atm. chem., including near complete removal and deposition of mercury, alteration of oxidn. fates for org. gases, and export of bromine into the free troposphere. Recent changes in the climate of the Arctic and state of the Arctic sea ice cover are likely to have strong effects on halogen activation and ODEs; however, more research is needed to make meaningful predictions of these changes.
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    10. 10
      O’Dowd, C. D.; Facchini, M. C.; Cavalli, F.; Ceburnis, D.; Mircea, M.; Decesari, S.; Fuzzi, S.; Yoon, Y. J.; Putaud, J.-P. Biogenically driven organic contribution to marine aerosol. Nature 2004, 431 (7009), 676– 680,  DOI: 10.1038/nature02959
      10
      Biogenically driven organic contribution to marine aerosol
      O'Dowd, Colin D.; Facchini, Maria Cristina; Cavalli, Fabrizia; Ceburnis, Darius; Mircea, Mihaela; Decesari, Stefano; Fuzzi, Sandro; Yoon, Young Jun; Putaud, Jean-Philippe
      Nature (London, United Kingdom) (2004), 431 (7009), 676-680CODEN: NATUAS; ISSN:0028-0836. (Nature Publishing Group)
      Marine aerosol contributes significantly to the global aerosol load and consequently has an important impact on both the Earth's albedo and climate. So far, much of the focus on marine aerosol has centered on the prodn. of aerosol from sea-salt and non-sea-salt sulfates. Recent field expts., however, have shown that known aerosol prodn. processes for inorg. species cannot account for the entire aerosol mass that occurs in submicrometer sizes. Several exptl. studies have pointed to the presence of significant concns. of org. matter in marine aerosol. There is some information available about the compn. of org. matter, but the contribution of org. matter to marine aerosol, as a function of aerosol size, as well as its characterization as hydrophilic or hydrophobic, has been lacking. Here we measure the phys. and chem. characteristics of ≤ 1 μm marine aerosol over the North Atlantic Ocean during plankton blooms progressing from spring through to autumn. We find that during bloom periods, the org. fraction dominates and contributes 63% to the submicrometer aerosol mass (about 45% is water-insol. and about 18% water-sol.). In winter, when biol. activity is at its lowest, the org. fraction decreases to 15%. Our model simulations indicate that org. matter can enhance the cloud droplet concn. by 15% to more than 100% and is therefore an important component of the aerosol-cloud-climate feedback system involving marine biota.
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    11. 11
      Prather, K. A.; Bertram, T. H.; Grassian, V. H.; Deane, G. B.; Stokes, M. D.; DeMott, P. J.; Aluwihare, L. I.; Palenik, B. P.; Azam, F.; Seinfeld, J. H.; Moffet, R. C.; Molina, M. J.; Cappa, C. D.; Geiger, F. M.; Roberts, G. C.; Russell, L. M.; Ault, A. P.; Baltrusaitis, J.; Collins, D. B.; Corrigan, C. E.; Cuadra-Rodriguez, L. A.; Ebben, C. J.; Forestieri, S. D.; Guasco, T. L.; Hersey, S. P.; Kim, M. J.; Lambert, W. F.; Modini, R. L.; Mui, W.; Pedler, B. E.; Ruppel, M. J.; Ryder, O. S.; Schoepp, N. G.; Sullivan, R. C.; Zhao, D. Bringing the ocean into the laboratory to probe the chemical complexity of sea spray aerosol. Proc. Natl. Acad. Sci. U. S. A. 2013, 110 (19), 7550– 7555,  DOI: 10.1073/pnas.1300262110
      11
      Bringing the ocean into the laboratory to probe the chemical complexity of sea spray aerosol
      Prather, Kimberly A.; Bertram, Timothy H.; Grassian, Vicki H.; Deane, Grant B.; Stokes, M. Dale; DeMott, Paul J.; Aluwihare, Lihini I.; Palenik, Brian P.; Azam, Farooq; Seinfeld, John H.; Moffet, Ryan C.; Molina, Mario J.; Cappa, Christopher D.; Geiger, Franz M.; Roberts, Gregory C.; Russell, Lynn M.; Ault, Andrew P.; Baltrusaitis, Jonas; Collins, Douglas B.; Corrigan, Craig E.; Cuadra-Rodriguez, Luis A.; Ebben, Carlena J.; Forestieri, Sara D.; Guasco, Timothy L.; Hersey, Scott P.; Kim, Michelle J.; Lambert, William F.; Modini, Robin L.; Mui, Wilton; Pedler, Byron E.; Ruppel, Matthew J.; Ryder, Olivia S.; Schoepp, Nathan G.; Sullivan, Ryan C.; Zhao, Defeng
      Proceedings of the National Academy of Sciences of the United States of America (2013), 110 (19), 7550-7555, S7550/1-S7550/10CODEN: PNASA6; ISSN:0027-8424. (National Academy of Sciences)
      The prodn., size, and chem. compn. of sea spray aerosol (SSA) particles strongly depend on seawater chem., which is controlled by phys., chem., and biol. processes. Despite decades of marine environment studies, a direct relationship has yet to be established between ocean biol. and physicochem. SSA properties. The ability to establish such relationships is hindered because SSA measurements are typically dominated by overwhelming background aerosol concns., even in remote marine environments. This work describes a newly developed approach to reproduce SSA chem. complexity a lab. setting, comprising a unique ocean/atm. facility equipped with actual breaking waves. A mesocosm expt., performed with natural seawater using controlled phytoplankton and heterotrophic bacteria concns., showed SSA size and chem. mixing state are acutely sensitive to the aerosol prodn. mechanism and to the type of biol. species present. The largest redn. in SSA hygroscopicity occurred as heterotrophic bacteria concns. increased, whereas phytoplankton and chlorophyll-a concns. decreased, directly corresponding to a change in mixing state in the smallest size range (60-180 nm). Using this newly developed approach to generate realistic SSA, systematic studies can now be performed to advance the fundamental understanding of the effect of ocean biol. on SSA chem. mixing state, heterogeneous reactivity, and resulting climate-relevant properties.
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    12. 12
      van Pinxteren, M.; Fomba, K. W.; Triesch, N.; Stolle, C.; Wurl, O.; Bahlmann, E.; Gong, X.; Voigtländer, J.; Wex, H.; Robinson, T. B.; Barthel, S.; Zeppenfeld, S.; Hoffmann, E. H.; Roveretto, M.; Li, C.; Grosselin, B.; Daële, V.; Senf, F.; van Pinxteren, D.; Manzi, M.; Zabalegui, N.; Frka, S.; Gašparović, B.; Pereira, R.; Li, T.; Wen, L.; Li, J.; Zhu, C.; Chen, H.; Chen, J.; Fiedler, B.; von Tümpling, W.; Read, K. A.; Punjabi, S.; Lewis, A. C.; Hopkins, J. R.; Carpenter, L. J.; Peeken, I.; Rixen, T.; Schulz-Bull, D.; Monge, M. E.; Mellouki, A.; George, C.; Stratmann, F.; Herrmann, H. Marine organic matter in the remote environment of the Cape Verde islands – an introduction and overview to the MarParCloud campaign. Atmos. Chem. Phys. 2020, 20 (11), 6921– 6951,  DOI: 10.5194/acp-20-6921-2020
      12
      Marine organic matter in the remote environment of the Cape Verde islands - an introduction and overview to the MarParCloud campaign
      van Pinxteren, Manuela; Fomba, Khanneh Wadinga; Triesch, Nadja; Stolle, Christian; Wurl, Oliver; Bahlmann, Enno; Gong, Xianda; Voigtlaender, Jens; Wex, Heike; Robinson, Tiera-Brandy; Barthel, Stefan; Zeppenfeld, Sebastian; Hoffmann, Erik Hans; Roveretto, Marie; Li, Chunlin; Grosselin, Benoit; Daele, Veronique; Senf, Fabian; van Pinxteren, Dominik; Manzi, Malena; Zabalegui, Nicolas; Frka, Sanja; Gasparovic, BlaZenka; Pereira, Ryan; Li, Tao; Wen, Liang; Li, Jiarong; Zhu, Chao; Chen, Hui; Chen, Jianmin; Fiedler, Bjoern; von Tuempling, Wolf; Read, Katie Alana; Punjabi, Shalini; Lewis, Alastair Charles; Hopkins, James Roland; Carpenter, Lucy Jane; Peeken, Ilka; Rixen, Tim; Schulz-Bull, Detlef; Monge, Maria Eugenia; Mellouki, Abdelwahid; George, Christian; Stratmann, Frank; Herrmann, Hartmut
      Atmospheric Chemistry and Physics (2020), 20 (11), 6921-6951CODEN: ACPTCE; ISSN:1680-7324. (Copernicus Publications)
      The project MarParCloud (Marine biol. prodn., org. aerosol Particles and marine Clouds: a process chain) aims to improve our understanding of the genesis, modification and impact of marine org. matter (OM) from its biol. prodn., to its export to marine aerosol particles and, finally, to its ability to act as ice nucleating particles (INPs) and cloud condensation nuclei (CCN). A field campaign at the Cape Verde Atm. Observatory (CVAO) in the tropics in Sept.-Oct. 2017 formed the core of this project that was jointly performed with the project MARSU (MARine atm. Science Unravelled). A suite of chem., phys., biol. and meteorol. techniques was applied, and comprehensive measurements of bulk water, the sea surface microlayer (SML), cloud water and ambient aerosol particles collected at a ground based and a mountain station took place. Key variables comprised the chem. characterization of the atmospherically relevant OM components in the ocean and the atm. as well as measurements of INPs and CCN. Moreover, bacterial cell counts, mercury species and trace gases were analyzed. To interpret the results, the measurements were accompanied by various auxiliary parameters such as air mass back-trajectory anal., vertical atm. profile anal., cloud observations and pigment measurements in seawater. Addnl. modeling studies supported the exptl. anal. During the campaign, the CVAO exhibited marine air masses with low and partly moderate dust influences. The marine boundary layer was well mixed as indicated by an almost uniform particle no. size distribution within the boundary layer. Lipid biomarkers were present in the aerosol particles in typical concns. of marine background conditions. Accumulation and coarse mode particles served as CCN and were efficiently transferred to the cloud water. The ascent of ocean derived compds., such as sea salt and sugar like compds., to the cloud level, as derived from chem. anal. and atm. transfer modeling results, denotes an influence of marine emissions on cloud formation. Org. nitrogen compds. (free amino acids) were enriched by several orders of magnitude in submicron aerosol particles and in cloud water compared to seawater. However, INP measurements also indicated a significant contribution of other non marine sources to the local INP concn., as (biol. active) INPs were mainly present in supermicron aerosol particles that are not suggested to undergo strong enrichment during ocean atm. transfer. In addn., the no. of CCN at the supersatn. of 0.30% was about 2.5 times higher during dust periods compared to marine periods. Lipids, sugar like compds., UV-absorbing (UV: UV) humic like substances and low mol. wt. neutral components were important org. compds. in the seawater, and highly surface-active lipids were enriched within the SML. The selective enrichment of specific org. compds. in the SML needs to be studied in further detail and implemented in an OM source function for emission modeling to better understand transfer patterns, the mechanisms of marine OM transformation in the atm. and the role of addnl. sources. In summary, when looking at particulate mass, we see oceanic compds. transferred to the atm. aerosol and to the cloud level, while from a perspective of particle no. concns., sea spray aerosol (i.e., primary marine aerosol) contributions to both CCN and INPs are rather limited.
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    13. 13
      Mata, J.; Varade, D.; Ghosh, G.; Bahadur, P. Effect of tetrabutylammonium bromide on the micelles of sodium dodecyl sulfate. Colloids Surf., A 2004, 245 (1), 69– 73,  DOI: 10.1016/j.colsurfa.2004.07.009
      13
      Effect of tetrabutylammonium bromide on the micelles of sodium dodecyl sulfate
      Mata, J.; Varade, D.; Ghosh, G.; Bahadur, P.
      Colloids and Surfaces, A: Physicochemical and Engineering Aspects (2004), 245 (1-3), 69-73CODEN: CPEAEH; ISSN:0927-7757. (Elsevier B.V.)
      Micellar behavior of sodium dodecyl sulfate (NaDS) was examd. in the presence of tetrabutylammonium bromide (TBABr) by surface tension, viscosity, dynamic light scattering (DLS), dye solubilization, and cloud point measurements. NaDS showed enhanced solubilization properties and a remarkable decrease in surface tension and crit. micelle concn. (CMC) in presence of TBABr. Both viscosity and DLS showed growth in NaDS micelles (50 mM) above 100 mM TBABr concn.; sphere-to-rod transition and micellar growth obsd. till 200 mM, above which soln. undergoes phase sepn. The results are explained on the basis of the binding ability of bulky tetrabutylammonium ion on NaDS.
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    14. 14
      Cochran, R. E.; Ryder, O. S.; Grassian, V. H.; Prather, K. A. Sea Spray Aerosol: The Chemical Link between the Oceans, Atmosphere, and Climate. Acc. Chem. Res. 2017, 50 (3), 599– 604,  DOI: 10.1021/acs.accounts.6b00603
      14
      Sea Spray Aerosol: The Chemical Link between the Oceans, Atmosphere, and Climate
      Cochran, Richard E.; Ryder, Olivia S.; Grassian, Vicki H.; Prather, Kimberly A.
      Accounts of Chemical Research (2017), 50 (3), 599-604CODEN: ACHRE4; ISSN:0001-4842. (American Chemical Society)
      To make connections between lab. and field study results, unique approaches have been developed to bring real-world complexity of sea spray aerosols (SSA) into the lab. to allow direct investigation of microscopic and mol. processes. From these studies, it was discovered that nascent SSA contains a highly diverse population of particles with respect to chem. compn. which is directly affected by dynamic phys. and biol. processes occurring in the ocean. While some properties of nascent SSA, including ice nucleating ability and particle morphol., have displayed strong changes in response to microbial-induced alterations to SSA chem. compn., others, such as cloud condensation nuclei propensity and heterogeneous reactions with certain trace gases remain surprisingly unaffected. Results of gas-phase mols. and water uptake by nascent SSA has been shown to differ from those obtained using simple model system. This suggests the interfacial chem. of nascent SSA involves a synergistic array of multiple processes and interactions. Topics discussed include: ocean and atm. inter-connected through chem.; producing representative SSA; understanding the effect of interfacial interactions and ocean biol. on SSA compn.; chem.-driven interactions among SSA, trace atm. gases, and water; and summary and future prospects.
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    15. 15
      Ciuraru, R.; Fine, L.; van Pinxteren, M.; D’Anna, B.; Herrmann, H.; George, C. Photosensitized production of functionalized and unsaturated organic compounds at the air-sea interface. Sci. Rep. 2015, 5 (1), 12741,  DOI: 10.1038/srep12741
      15
      Photosensitized production of functionalized and unsaturated organic compounds at the air-sea interface
      Ciuraru, Raluca; Fine, Ludovic; van Pinxteren, Manuela; D'Anna, Barbara; Herrmann, Hartmut; George, Christian
      Scientific Reports (2015), 5 (), 12741CODEN: SRCEC3; ISSN:2045-2322. (Nature Publishing Group)
      The sea-surface microlayer (SML) has different phys., chem. and biol. properties compared to the subsurface water, with an enrichment of org. matter i.e., dissolved org. matter including UV absorbing humic substances, fatty acids and many others. Here we present exptl. evidence that dissolved org. matter, such as humic acids, when exposed to sunlight, can photosensitize the chem. conversion of linear satd. fatty acids at the air-water interface into unsatd. functionalized gas phase products (i.e. satd. and unsatd. aldehydes and acids, alkenes and dienes,...) which are known precursors of secondary org. aerosols. These functionalized mols. have previously been thought to be of biol. origin, but here we demonstrate that abiotic interfacial photochem. has the potential to produce such mols. As the ocean is widely covered by the SML, this new understanding will impact on our ability to describe atm. chem. in the marine environment.
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    16. 16
      Alpert, P. A.; Ciuraru, R.; Rossignol, S.; Passananti, M.; Tinel, L.; Perrier, S.; Dupart, Y.; Steimer, S. S.; Ammann, M.; Donaldson, D. J.; George, C. Fatty Acid Surfactant Photochemistry Results in New Particle Formation. Sci. Rep. 2017, 7 (1), 12693,  DOI: 10.1038/s41598-017-12601-2
      16
      Fatty Acid Surfactant Photochemistry Results in New Particle Formation
      Alpert Peter A; Ciuraru Raluca; Rossignol Stephanie; Passananti Monica; Tinel Liselotte; Perrier Sebastien; Dupart Yoan; George Christian; Alpert Peter A; Steimer Sarah S; Ammann Markus; Ciuraru Raluca; Rossignol Stephanie; Passananti Monica; Tinel Liselotte; Steimer Sarah S; Donaldson D James
      Scientific reports (2017), 7 (1), 12693 ISSN:.
      Organic interfaces that exist at the sea surface microlayer or as surfactant coatings on cloud droplets are highly concentrated and chemically distinct from the underlying bulk or overlying gas phase. Therefore, they may be potentially unique locations for chemical or photochemical reactions. Recently, photochemical production of volatile organic compounds (VOCs) was reported at a nonanoic acid interface however, subsequent secondary organic aerosol (SOA) particle production was incapable of being observed. We investigated SOA particle formation due to photochemical reactions occurring at an air-water interface in presence of model saturated long chain fatty acid and alcohol surfactants, nonanoic acid and nonanol, respectively. Ozonolysis of the gas phase photochemical products in the dark or under continued UV irradiation both resulted in nucleation and growth of SOA particles. Irradiation of nonanol did not yield detectable VOC or SOA production. Organic carbon functionalities of the SOA were probed using X-ray microspectroscopy and compared with other laboratory generated and field collected particles. Carbon-carbon double bonds were identified in the condensed phase which survived ozonolysis during new particle formation and growth. The implications of photochemical processes occurring at organic coated surfaces are discussed in the context of marine SOA particle atmospheric fluxes.
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    17. 17
      Ammann, M.; Cox, R. A.; Crowley, J. N.; Jenkin, M. E.; Mellouki, A.; Rossi, M. J.; Troe, J.; Wallington, T. J. Evaluated kinetic and photochemical data for atmospheric chemistry: Volume VI – heterogeneous reactions with liquid substrates. Atmos. Chem. Phys. 2013, 13 (16), 8045– 8228,  DOI: 10.5194/acp-13-8045-2013
      17
      Evaluated kinetic and photochemical data for atmospheric chemistry: Volume VI - heterogeneous reactions with liquid substrates
      Ammann, M.; Cox, R. A.; Crowley, J. N.; Jenkin, M. E.; Mellouki, A.; Rossi, M. J.; Troe, J.; Wallington, T. J.
      Atmospheric Chemistry and Physics (2013), 13 (16), 8045-8228, 184 pp.CODEN: ACPTCE; ISSN:1680-7324. (Copernicus Publications)
      A review. This article, the sixth in the ACP journal series, presents data evaluated by the IUPAC Task Group on Atm. Chem. Kinetic Data Evaluation. It covers the heterogeneous processes involving liq. particles present in the atm. with an emphasis on those relevant for the upper troposphere/lower stratosphere and the marine boundary layer, for which uptake coeffs. and adsorption parameters have been presented on the IUPAC website since 2009. The article consists of an introduction and guide to the evaluation, giving a unifying framework for parameterisation of atm. heterogeneous processes. We provide summary sheets contg. the recommended uptake parameters for the evaluated processes. The exptl. data on which the recommendations are based are provided in data sheets in sep. appendices for the four surfaces considered: liq. water, deliquesced halide salts, other aq. electrolytes and sulfuric acid.
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    18. 18
      Clifford, D.; Donaldson, D. J. Direct Experimental Evidence for a Heterogeneous Reaction of Ozone with Bromide at the Air–Aqueous Interface. J. Phys. Chem. A 2007, 111 (39), 9809– 9814,  DOI: 10.1021/jp074315d
      18
      Direct Experimental Evidence for a Heterogeneous Reaction of Ozone with Bromide at the Air-Aqueous Interface
      Clifford, Daniel; Donaldson, D. J.
      Journal of Physical Chemistry A (2007), 111 (39), 9809-9814CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)
      Recent exptl. and theor. evidence has indicated an enhancement of the heavier halide ions at the air-aq. interface, relative to their bulk concns. This, along with an order of magnitude discrepancy between measured and predicted Br2 prodn. in the reaction of ozone with deliquesced NaBr aerosol, has led to the suggestion that an interface reaction occurs between ozone and bromide. We have used harmine, a β-carboline alkaloid, as an interface-sensitive fluorescent pH probe in order to measure pH changes assocd. with the interfacial reaction of ozone and bromide. The rate of pH change depends upon the bulk bromide concn. in a way which is well described by a Langmuir-Hinshelwood kinetic model. In the presence of octanol at the interface, the rate of pH change tracks the octanol adsorption isotherm, as expected if octanol enhances the concn. of ozone at the surface.
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    19. 19
      Oldridge, N. W.; Abbatt, J. P. D. Formation of Gas-Phase Bromine from Interaction of Ozone with Frozen and Liquid NaCl/NaBr Solutions: Quantitative Separation of Surficial Chemistry from Bulk-Phase Reaction. J. Phys. Chem. A 2011, 115 (12), 2590– 2598,  DOI: 10.1021/jp200074u
      19
      Formation of Gas-Phase Bromine from Interaction of Ozone with Frozen and Liquid NaCl/NaBr Solutions: Quantitative Separation of Surficial Chemistry from Bulk-Phase Reaction
      Oldridge, N. W.; Abbatt, J. P. D.
      Journal of Physical Chemistry A (2011), 115 (12), 2590-2598CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)
      The formation kinetics of gas-phase bromine (Br2) from interaction of gas-phase ozone (O3) with frozen and liq. solns. of NaCl (0.55 M) and NaBr (largely from 1.7 to 8.5 mM) have been studied from -40° to 0° in a coated-wall flow tube coupled to a chem. ionization mass spectrometer. The reactive uptake coeff. for O3 is deduced from the product formation rate and then studied as a function of exptl. conditions. In particular, for both the liq. and frozen solns., we find that the uptake coeff. is inversely dependent on the gas-phase O3 concn. in a manner that is quant. consistent with both surface- and bulk-phase kinetics. The reaction is fastest on acidic media (pH of the starting soln. down to 2) but also proceeds at an appreciable rate on neutral substrates. Above 253 K, the uptake coeff. increases with increasing temp. on frozen solns., consistent with an increasing brine content. The similarity of the abs. magnitude and form of the kinetics on the frozen and liq. substrates suggests that the reaction on the frozen soln. is occurring with the assocd. brine, and not with the ice bulk or a quasi-liq. layer existing on the ice. The implications of these results to bromine activation in the tropospheric boundary layer are made.
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    20. 20
      Artiglia, L.; Edebeli, J.; Orlando, F.; Chen, S.; Lee, M.-T.; Corral Arroyo, P.; Gilgen, A.; Bartels-Rausch, T.; Kleibert, A.; Vazdar, M.; Andres Carignano, M.; Francisco, J. S.; Shepson, P. B.; Gladich, I.; Ammann, M. A surface-stabilized ozonide triggers bromide oxidation at the aqueous solution-vapour interface. Nat. Commun. 2017, 8 (1), 700,  DOI: 10.1038/s41467-017-00823-x
      20
      A surface-stabilized ozonide triggers bromide oxidation at the aqueous solution-vapour interface
      Artiglia Luca; Edebeli Jacinta; Orlando Fabrizio; Chen Shuzhen; Lee Ming-Tao; Corral Arroyo Pablo; Gilgen Anina; Bartels-Rausch Thorsten; Ammann Markus; Artiglia Luca; Edebeli Jacinta; Chen Shuzhen; Gilgen Anina; Lee Ming-Tao; Corral Arroyo Pablo; Kleibert Armin; Vazdar Mario; Andres Carignano Marcelo; Gladich Ivan; Francisco Joseph S; Shepson Paul B
      Nature communications (2017), 8 (1), 700 ISSN:.
      Oxidation of bromide in aqueous environments initiates the formation of molecular halogen compounds, which is important for the global tropospheric ozone budget. In the aqueous bulk, oxidation of bromide by ozone involves a [Br•OOO(-)] complex as intermediate. Here we report liquid jet X-ray photoelectron spectroscopy measurements that provide direct experimental evidence for the ozonide and establish its propensity for the solution-vapour interface. Theoretical calculations support these findings, showing that water stabilizes the ozonide and lowers the energy of the transition state at neutral pH. Kinetic experiments confirm the dominance of the heterogeneous oxidation route established by this precursor at low, atmospherically relevant ozone concentrations. Taken together, our results provide a strong case of different reaction kinetics and mechanisms of reactions occurring at the aqueous phase-vapour interface compared with the bulk aqueous phase.Heterogeneous oxidation of bromide in atmospheric aqueous environments has long been suspected to be accelerated at the interface between aqueous solution and air. Here, the authors provide spectroscopic, kinetic and theoretical evidence for a rate limiting, surface active ozonide formed at the interface.
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    21. 21
      Edebeli, J.; Ammann, M.; Bartels-Rausch, T. Microphysics of the aqueous bulk counters the water activity driven rate acceleration of bromide oxidation by ozone from 289–245 K. Environ. Sci.: Processes Impacts 2019, 21 (1), 63– 73,  DOI: 10.1039/C8EM00417J
      21
      Microphysics of the aqueous bulk counters the water activity driven rate acceleration of bromide oxidation by ozone from 289-245 K
      Edebeli, Jacinta; Ammann, Markus; Bartels-Rausch, Thorsten
      Environmental Science: Processes & Impacts (2019), 21 (1), 63-73CODEN: ESPICZ; ISSN:2050-7895. (Royal Society of Chemistry)
      The reaction of ozone with bromide is an initiation process in bromine activation resulting in the formation of reactive bromine species with impacts on the fate of compds. in the lower atm. Environmental halide sources often contain orgs., which are known to influence aq. bulk reactivity. Here, we present a study investigating the temp. dependence of bromide oxidn. by ozone using a coated wall flow tube reactor coated with an aq. mixt. of citric acid, as a proxy for oxidized secondary org. matter, and sodium bromide. Using the resistor model formulation, we quantify changes in the properties of the aq. bulk relevant for the obsd. reactivity. The reactive uptake coeff. decreased from 2 × 10-6 at 289 K to 0.5 × 10-6 at 245 K. Our anal. indicates that the humidity-driven increase in concn. with a corresponding increase in the pseudo-first order reaction rate was countered by the colligative change in ozone soly. and the effect of the org. fraction via increased viscosity and decreased diffusivity of ozone as the temp. decreased. From our parameterization, we provide an extension of the temp. dependence of the reaction rate coeffs. driving the oxidn. of bromide, and assess the temp.-dependent salting effects of citric acid on ozone soly. This study shows the effects of the org. species at relatively mild temps., between the f.p. and eutectic temp. of sea as is typical for the Earth's cryosphere. Thus, this study may be relevant for atm. models at different scales describing halogen activation in the marine boundary layer or free troposphere including matrixes such as sea-spray aerosol and brine in sea ice, snow, and around mid-latitude salt lakes.
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    22. 22
      Sakamoto, Y.; Goda, M.; Hirokawa, J. Kinetics Study of Heterogeneous Bromine Release from the Reaction between Gaseous Ozone and Aqueous Bromide Solution. J. Phys. Chem. A 2018, 122 (10), 2723– 2731,  DOI: 10.1021/acs.jpca.7b12819
      22
      Kinetics Study of Heterogeneous Bromine Release from the Reaction between Gaseous Ozone and Aqueous Bromide Solution
      Sakamoto, Yosuke; Goda, Motoki; Hirokawa, Jun
      Journal of Physical Chemistry A (2018), 122 (10), 2723-2731CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)
      The heterogeneous release of mol. bromine, Br2, from the reaction between gaseous ozone and aq. bromide ion in seawater ice and sea salt aerosols is considered to be an initial source of reactive bromine species in the troposphere. Recent studies have demonstrated that the uptake of ozone by aq. bromide soln. is promoted by reactions at the gas-liq. interface. The present work investigated the heterogeneous reaction between gaseous ozone and aq. bromide soln. at atm. pressure and room temp. using a wetted wall flow reactor combined with a chem. ionization mass spectrometer. The emission rate of Br2 was measured as a function of gaseous ozone concn., aq. bromide concn., and pH. In addn., we conducted a simple kinetics model simulation that included only bulk aq.-phase reactions and compared the theor. values with the exptl. detd. values. The Br2 emission rates measured exptl. differ from the simulated rates at relatively high bromide concn., as well as in the pH region of 6-9. These differences might be explained by different Br- concn. and/or deprotonation efficiency near the interface region and those in the bulk soln.
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    23. 23
      Jung, Y.; Hong, E.; Kwon, M.; Kang, J.-W. A kinetic study of ozone decay and bromine formation in saltwater ozonation: Effect of O3 dose, salinity, pH, and temperature. Chem. Eng. J. 2017, 312, 30– 38,  DOI: 10.1016/j.cej.2016.11.113
      23
      A kinetic study of ozone decay and bromine formation in saltwater ozonation: Effect of O3 dose, salinity, pH, and temperature
      Jung, Youmi; Hong, Eunkyung; Kwon, Minhwan; Kang, Joon-Wun
      Chemical Engineering Journal (Amsterdam, Netherlands) (2017), 312 (), 30-38CODEN: CMEJAJ; ISSN:1385-8947. (Elsevier B.V.)
      Saltwater ozonization is used to remove invasive or pathogenic organisms from ballast water and water in the aquaculture industry. Ozone chem. in saltwater is considerably different to that in freshwater. In saltwater, ozone rapidly decomps. to produce bromine, which is a main disinfectant in saltwater ozonization. It is very difficult to sep. ozone and bromine in saltwater ozonization. In this study, we developed a model for prediction of residual ozone and bromine concns., and applied this model to calc. Ct value (Concn. of disinfectant x Contact time) for disinfection. The contributions of ozone-Ct and bromine-Ct to organism removal were studied using the zooplankton, Artemia salina. Interestingly, the removal efficiency of saltwater ozonization for A. salina (47%) was the same as the sum of the removal efficiencies for bromine (32%) and ozone (14%) used on their own. This indicates that both bromine and trace ozone kill A. salina during saltwater ozonization. The prediction model for residual ozone and bromine formation was verified in different ozone dose, water salinity, pH, and temp., which affect ozone decompn. and bromine formation.
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    24. 24
      Moreno, C.; Baeza-Romero, M. T. A kinetic model for ozone uptake by solutions and aqueous particles containing I– and Br–, including seawater and sea-salt aerosol. Phys. Chem. Chem. Phys. 2019, 21 (36), 19835– 19856,  DOI: 10.1039/C9CP03430G
      24
      A kinetic model for ozone uptake by solutions and aqueous particles containing I- and Br-, including seawater and sea-salt aerosol
      Moreno, Carolina; Baeza-Romero, Maria Teresa
      Physical Chemistry Chemical Physics (2019), 21 (36), 19835-19856CODEN: PPCPFQ; ISSN:1463-9076. (Royal Society of Chemistry)
      The heterogeneous interactions of gaseous ozone (O3) with seawater and with sea-salt aerosols are known to generate volatile halogen species, which, in turn, lead to further destruction of O3. Here, a kinetic model for the interaction of ozone (O3) with Br- and I- solns. and aq. particles has been proposed that satisfactorily explains previous literature studies about this process. Apart from the aq.-phase reactions X- + O3 (X = I, Br), the interaction also involves the surface reactions X- + O3 that occur via O3 adsorption on the aq. surface. In single salt solns. and aerosols, the partial order in ozone and the total order of the surface reactions are one, but the apparent total order is second order because the no. of ozone sites where reaction can occur is equal to the surficial concn. of X- ([X-]surf). In the presence of Cl-, the surface reactions are enhanced by a factor equal to 1 + krX-[Cl-]surf where krI- ≈ 3 x 10-4. Therefore, we have inferred that Cl- acts as a catalyst in the surface reactions X- + O3. The model has been applied to est. ozone uptake by the reaction with these halides in/on seawater and in/on sea-salt aerosol, where it has been concluded that the Cl--catalyzed surface reaction is important relative to total ozone uptake and should therefore be considered to model Y/YO (Y = I, Br, Cl) levels in the troposphere.
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    25. 25
      Hunt, S. W.; Roeselová, M.; Wang, W.; Wingen, L. M.; Knipping, E. M.; Tobias, D. J.; Dabdub, D.; Finlayson-Pitts, B. J. Formation of Molecular Bromine from the Reaction of Ozone with Deliquesced NaBr Aerosol: Evidence for Interface Chemistry. J. Phys. Chem. A 2004, 108 (52), 11559– 11572,  DOI: 10.1021/jp0467346
      25
      Formation of Molecular Bromine from the Reaction of Ozone with Deliquesced NaBr Aerosol: Evidence for Interface Chemistry
      Hunt, S. W.; Roeselova, M.; Wang, W.; Wingen, L. M.; Knipping, E. M.; Tobias, D. J.; Dabdub, D.; Finlayson-Pitts, B. J.
      Journal of Physical Chemistry A (2004), 108 (52), 11559-11572CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)
      The reaction of ozone with aq. sodium bromide particles is investigated with a combination of aerosol chamber expts., kinetics modeling, and mol. dynamics simulations. The mol. bromine prodn. in the chamber expts. is approx. an order of magnitude greater than that predicted by known chem. in the gas and bulk aq. phases with use of a comprehensive computer kinetics model. Mol. dynamics simulations indicate that ozone has significant residence time at the air-soln. interface, while making frequent contacts with bromide ions for as long as 50 ps in the surface layer of a 6.1 M NaBr soln. The formation of a complex between ozone and bromide ion, [O3···Br-], which can lead to prodn. of Br2 by reaction at the air-water interface, is therefore feasible. Exptl. obsd. Br2 is well predicted by including an interface process with a reaction probability of [1.9 ± 0.8] × 10-6 (1 s) as the first step in a surface mechanism to produce addnl. gas-phase Br2. An est. of the impact of this interface reaction on bromine formation in the marine boundary layer shows that several ppt of bromine could potentially be produced during the night from this proposed surface chem.
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    26. 26
      Oum, K. W.; Lakin, M. J.; Finlayson-Pitts, B. J. Bromine activation in the troposphere by the dark reaction of O3 with seawater ice. Geophys. Res. Lett. 1998, 25 (21), 3923– 3926,  DOI: 10.1029/1998GL900078
      26
      Bromine activation in the troposphere by the dark reaction of O3 with seawater ice
      Oum, K. W.; Lakin, M. J.; Finlayson-Pitts, B. J.
      Geophysical Research Letters (1998), 25 (21), 3923-3926CODEN: GPRLAJ; ISSN:0094-8276. (American Geophysical Union)
      There is increasing evidence that Br2 atoms play a role in tropospheric chem. in the marine boundary layer. In addn., they are believed to lead to rapid depletion of surface level O3 in the Arctic at polar sunrise. While mechanisms have been proposed for recycling Br2 atoms from sea salt particles, the initial reaction(s) leading to the formation of Br atom precursors is not known. Formation of gaseous Br2 from the reaction of seawater ice with O3 in the dark is reported. These observations suggested this reaction is a potential source of tropospheric photolyzable Br2 in high latitude coastal regions in winter. In addn., it may be the source of the photolyzable Br2 gas measured recently in the Arctic by G.A. Impey, et al. (1997), believed to be responsible for O3 destruction at polar sunrise.
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    27. 27
      Liu, Q.; Schurter, L. M.; Muller, C. E.; Aloisio, S.; Francisco, J. S.; Margerum, D. W. Kinetics and Mechanisms of Aqueous Ozone Reactions with Bromide, Sulfite, Hydrogen Sulfite, Iodide, and Nitrite Ions. Inorg. Chem. 2001, 40 (17), 4436– 4442,  DOI: 10.1021/ic000919j
      27
      Kinetics and Mechanisms of Aqueous Ozone Reactions with Bromide, Sulfite, Hydrogen Sulfite, Iodide, and Nitrite Ions
      Liu, Qian; Schurter, Lynn M.; Muller, Charles E.; Aloisio, Simone; Francisco, Joseph S.; Margerum, Dale W.
      Inorganic Chemistry (2001), 40 (17), 4436-4442CODEN: INOCAJ; ISSN:0020-1669. (American Chemical Society)
      Reactions of ozone with Br-, SO32-, HSO3-, I-, and NO2-, studied by stopped-flow and pulsed-accelerated-flow techniques, are 1st order in the concn. of O3(aq) and 1st order in the concn. of each anion. The rate consts. increase by a factor of 5 × 106 as the nucleophilicities of the anions increase from Br- to SO32-. Ozone adducts with the nucleophiles are proposed as steady-state intermediates prior to oxygen atom transfer with release of O2. Ab initio calcns. show possible structures for the intermediates. The reaction between Br- and O3 is accelerated by H+ but exhibits a kinetic satn. effect as the acidity increases. The kinetics indicate formation of BrOOO- as a steady-state intermediate with an acid-assisted step to give BrOH and O2. Temp. dependencies of the reactions of Br- and HSO3- with O3 in acidic solns. are detd. from 1 to 25°. These kinetics are important in studies of annual ozone depletion in the Arctic troposphere at polar sunrise.
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    28. 28
      Donaldson, D. J.; Anderson, D. Does molecular HNO3 adsorb onto sulfuric acid droplet surfaces?. Geophys. Res. Lett. 1999, 26 (24), 3625– 3628,  DOI: 10.1029/1999GL010894
      28
      Does molecular HNO3 adsorb onto sulfuric acid droplet surfaces?
      Donaldson, D. J.; Anderson, Darren
      Geophysical Research Letters (1999), 26 (24), 3625-3628CODEN: GPRLAJ; ISSN:0094-8276. (American Geophysical Union)
      Room temp. surface tension measurements on the ternary system: nitric acid-sulfuric acid-water are reported. There is a dramatic decrease in the surface tension of sulfuric acid-water solns. as nitric acid is added. This decrease is most pronounced in the stratospherically-relevant range of sulfuric acid concns., between 50 and 75 wt% sulfuric acid. The surface tension decrease indicates a change in surface energy and surface compn. and/or structure assocd. with partitioning of mol. HNO3 to the surface. The presence of HNO3 at the surface may be related to the reported changes in heterogeneous reactivity of sulfuric acid solns. when exposed to nitric acid.
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    29. 29
      Ammann, M.; Artiglia, L.; Bartels-Rausch, T. Chapter 6 - X-Ray Excited Electron Spectroscopy to Study Gas–Liquid Interfaces of Atmospheric Relevance. In Physical Chemistry of Gas-Liquid Interfaces; Faust, J. A., House, J. E., Eds.; Elsevier, 2018; pp 135– 166.
      There is no corresponding record for this reference.
    30. 30
      Öhrwall, G.; Prisle, N. L.; Ottosson, N.; Werner, J.; Ekholm, V.; Walz, M.-M.; Björneholm, O. Acid–Base Speciation of Carboxylate Ions in the Surface Region of Aqueous Solutions in the Presence of Ammonium and Aminium Ions. J. Phys. Chem. B 2015, 119 (10), 4033– 4040,  DOI: 10.1021/jp509945g
      30
      Acid-base speciation of carboxylate ions in the surface region of aqueous solutions in the presence of ammonium and aminium ions
      Ohrwall Gunnar; Prisle Nonne L; Ottosson Niklas; Werner Josephina; Ekholm Victor; Walz Marie-Madeleine; Bjorneholm Olle
      The journal of physical chemistry. B (2015), 119 (10), 4033-40 ISSN:.
      The acid-base speciation of surface-active carboxylate ions in the surface region of aqueous solutions was studied with synchrotron-radiation-based photoelectron spectroscopy. The protonated form was found at an extraordinarily large fraction compared to that expected from the bulk pH. When adding salts containing the weak acid NH4(+) to the solution, the fraction of the acidic form at the surface increases, and to a much greater extent than expected from the bulk pH of the solution. We show that ammonium ions also are overrepresented in the surface region, and propose that the interaction between the surface-active anionic carboxylates and cationic ammonium ions creates a carboxylate-ammonium bilayer close to the surface, which increases the probability of the protonation of the carboxylate ions. By comparing the situation when a salt of the less volatile amine diethanolamine is used, we also show that the observed evaporation of ammonia that occurs after such an event only affects the equilibrium marginally.
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    31. 31
      Prisle, N.; Ottosson, N.; Öhrwall, G.; Söderström, J.; Maso, M. D.; Björneholm, O. Surface/bulk partitioning and acid/base speciation of aqueous decanoate: direct observations and atmospheric implications. Atmos. Chem. Phys. 2012, 12 (24), 12227– 12242,  DOI: 10.5194/acp-12-12227-2012
      31
      Surface/bulk partitioning and acid/base speciation of aqueous decanoate: direct observations and atmospheric implications
      Prisle, N. L.; Ottosson, N.; Ohrwall, G.; Soderstrom, J.; Dal Maso, M.; Bjorneholm, O.
      Atmospheric Chemistry and Physics (2012), 12 (24), 12227-12242CODEN: ACPTCE; ISSN:1680-7316. (Copernicus Publications)
      Dil. aq. solns. of the atm. org. surfactant sodium decanoate have been studied using surface sensitive XPS combined with synchrotron radiation. The decanoate/decanoic acid speciation and preferential adsorption was studied at the vapor-liq. interface, and the responses to mixing in soln. with some of the most common atm. inorg. ions, Na+, NH+4, Cl-, and SO2-4. Little or no influence of Na+, Cl-, or SO2-4 ions was obsd., on neither the relative speciation nor the individual adsorption properties of decanoate and decanoic acid. In particular, no significant salting-out effect due to common Na+ cations of the org. and inorg. salts was obsd. for these solns. On the other hand, mixing with NH+4 cations resulted in a pronounced surface enhancement of decanoic acid, which is attributed to surface specific acid-base chem. These changes in surface/bulk partitioning and surface speciation may significantly affect properties of aq. droplets contg. decanoate/decanoic acid, and potential implications for several processes crit. to the climate effects of atm. aerosols are discussed.
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    32. 32
      Lee, M.-T.; Brown, M. A.; Kato, S.; Kleibert, A.; Türler, A.; Ammann, M. Competition between organics and bromide at the aqueous solution–air interface as seen from ozone uptake kinetics and X-ray photoelectron spectroscopy. J. Phys. Chem. A 2015, 119 (19), 4600– 4608,  DOI: 10.1021/jp510707s
      32
      Competition between Organics and Bromide at the Aqueous Solution-Air Interface as Seen from Ozone Uptake Kinetics and X-ray Photoelectron Spectroscopy
      Lee, Ming-Tao; Brown, Matthew A.; Kato, Shunsuke; Kleibert, Armin; Turler, Andreas; Ammann, Markus
      Journal of Physical Chemistry A (2015), 119 (19), 4600-4608CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)
      Reaction of ozone (O3) with NaBr solns. in the presence and absence of citric acid (C6H8O7) under ambient conditions has been studied. Citric acid was used as a proxy for oxidized org. material present at the ocean surface or in sea spray aerosol. On neat NaBr solns., the obsd. kinetics was consistent with bulk reaction-limited uptake, and a second-order rate const. for the reaction of O3 + Br- is 57 ± 10 M-1 s-1. On mixed NaBr-citric acid aq. solns., the uptake kinetics was faster than that predicted by bulk reaction-limited uptake and also faster than expected based on an acid-catalyzed mechanism. XPS spectra on a liq. microjet of the same solns. at 1.0·10-3-1.0·10-4 mbar was used to obtain quant. insight into the interfacial compn. relative to that of the bulk solns. It revealed that the bromide anion was depleted by 30 ± 10% while the sodium cation gets enhanced by 40 ± 20% at the aq. soln.-air interface of a 0.12 M NaBr soln. mixed with 2.5 M citric acid in the bulk, attributed to the role of citric acid as a weak surfactant. Therefore, the enhanced reactivity of bromide solns. obsd. in the presence of citric acid was not necessarily attributable to a surface reaction but could also result from an increased soly. of ozone at higher citric acid concns. Whether the acid-catalyzed chem. may have a larger effect on the surface than in the bulk to offset the effect of bromide depletion also remains open.
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    33. 33
      Lee, M.-T.; Orlando, F.; Khabiri, M.; Roeselová, M.; Brown, M. A.; Ammann, M. The opposing effect of butanol and butyric acid on the abundance of bromide and iodide at the aqueous solution–air interface. Phys. Chem. Chem. Phys. 2019, 21 (16), 8418– 8427,  DOI: 10.1039/C8CP07448H
      33
      The opposing effect of butanol and butyric acid on the abundance of bromide and iodide at the aqueous solution-air interface
      Lee, Ming-Tao; Orlando, Fabrizio; Khabiri, Morteza; Roeselova, Martina; Brown, Matthew A.; Ammann, Markus
      Physical Chemistry Chemical Physics (2019), 21 (16), 8418-8427CODEN: PPCPFQ; ISSN:1463-9076. (Royal Society of Chemistry)
      The efficient oxidn. of iodide and bromide at the aq. soln.-air interface of the ocean or of sea spray aerosol particles had been suggested to be related to their surface propensity. The ubiquitous presence of org. material at the ocean surface calls for an assessment of the impact of often surface-active org. compds. on the interfacial d. of halide ions. The authors used in situ XPS with a liq. micro-jet to obtain chem. compn. information at aq. soln.-vapor interfaces from mixed aq. solns. contg. bromide or iodide and 1-butanol or butyric acid as org. surfactants. Core level spectra of Br 3d, Na 2s, C 1s and O 1s at ∼160 eV kinetic energy and core level spectra of I 4d and O 1s at ∼400 eV kinetic energy are compared for solns. with 1-butanol and butyric acid as a function of org. concn. A simple model was developed to account for the attenuation of photoelectrons by the aliph. C layer of the surfactants and for changing local d. of bromide and iodide in response to the presence of the surfactants. 1-Butanol increases the interfacial d. of bromide by 25%, while butyric acid reduces it by 40%, both in comparison to the pure aq. halide soln. Qual. similar behavior was obsd. for the case of iodide. Classical mol. dynamics simulations failed to reproduce the details of the response of the halide ions to the presence of the 2 orgs. This is attributed to the lack of correct monovalent ion parameters at low concn. possibly leading to an overestimation of the halide ion concn. at the interface in absence of orgs. Org. surfactants change the electrostatic interactions near the interface with headgroup specific effects. This has implications for halogen activation processes specifically when oxidants interact with halide ions at the aq. soln.-air interfaces of the ocean surface or sea spray aerosol particles.
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    34. 34
      Gladich, I.; Chen, S.; Vazdar, M.; Boucly, A.; Yang, H.; Ammann, M.; Artiglia, L. Surface Propensity of Aqueous Atmospheric Bromine at the Liquid–Gas Interface. J. Phys. Chem. Lett. 2020, 11 (9), 3422– 3429,  DOI: 10.1021/acs.jpclett.0c00633
      34
      Surface Propensity of Aqueous Atmospheric Bromine at the Liquid-Gas Interface
      Gladich, Ivan; Chen, Shuzhen; Vazdar, Mario; Boucly, Anthony; Yang, Huanyu; Ammann, Markus; Artiglia, Luca
      Journal of Physical Chemistry Letters (2020), 11 (9), 3422-3429CODEN: JPCLCD; ISSN:1948-7185. (American Chemical Society)
      Multiphase reactions of halide ions in aq. solns. exposed to the atm. initiate the formation of mol. halogen compds. in the gas phase. Their photolysis leads to halogen atoms, which are catalytic sinks for ozone, making these processes relevant for the regional and global tropospheric ozone budget. The affinity of halide ions in aq. soln. for the liq.-gas interface, which may influence their reactivity with gaseous species, has been debated. Our study focuses on the surface properties of the bromide ion and its oxidn. products. In situ XPS carried out on a liq. jet combined with classical and first-principles mol. dynamics calcns. was used to investigate the interfacial depth profile of bromide, hypobromite, hypobromous acid, and bromate. The simulated core electron binding energies support the exptl. obsd. values, which follow a correlation with bromine oxidn. state for the anion series. Bromide ions are homogeneously distributed in the soln. Hypobromous acid, a key species in the multiphase cycling of bromine, is the only species showing surface propensity, which suggests a more important role of the interface in multiphase bromine chem. than thought so far.
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    35. 35
      Lee, M.-T.; Brown, M. A.; Kato, S.; Kleibert, A.; Türler, A.; Ammann, M. Competition between Organics and Bromide at the Aqueous Solution–Air Interface as Seen from Ozone Uptake Kinetics and X-ray Photoelectron Spectroscopy. J. Phys. Chem. A 2015, 119 (19), 4600– 4608,  DOI: 10.1021/jp510707s
      35
      Competition between Organics and Bromide at the Aqueous Solution-Air Interface as Seen from Ozone Uptake Kinetics and X-ray Photoelectron Spectroscopy
      Lee, Ming-Tao; Brown, Matthew A.; Kato, Shunsuke; Kleibert, Armin; Turler, Andreas; Ammann, Markus
      Journal of Physical Chemistry A (2015), 119 (19), 4600-4608CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)
      Reaction of ozone (O3) with NaBr solns. in the presence and absence of citric acid (C6H8O7) under ambient conditions has been studied. Citric acid was used as a proxy for oxidized org. material present at the ocean surface or in sea spray aerosol. On neat NaBr solns., the obsd. kinetics was consistent with bulk reaction-limited uptake, and a second-order rate const. for the reaction of O3 + Br- is 57 ± 10 M-1 s-1. On mixed NaBr-citric acid aq. solns., the uptake kinetics was faster than that predicted by bulk reaction-limited uptake and also faster than expected based on an acid-catalyzed mechanism. XPS spectra on a liq. microjet of the same solns. at 1.0·10-3-1.0·10-4 mbar was used to obtain quant. insight into the interfacial compn. relative to that of the bulk solns. It revealed that the bromide anion was depleted by 30 ± 10% while the sodium cation gets enhanced by 40 ± 20% at the aq. soln.-air interface of a 0.12 M NaBr soln. mixed with 2.5 M citric acid in the bulk, attributed to the role of citric acid as a weak surfactant. Therefore, the enhanced reactivity of bromide solns. obsd. in the presence of citric acid was not necessarily attributable to a surface reaction but could also result from an increased soly. of ozone at higher citric acid concns. Whether the acid-catalyzed chem. may have a larger effect on the surface than in the bulk to offset the effect of bromide depletion also remains open.
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    36. 36
      Ge, X.; Wexler, A. S.; Clegg, S. L. Atmospheric amines – Part I. A review. Atmos. Environ. 2011, 45 (3), 524– 546,  DOI: 10.1016/j.atmosenv.2010.10.012
      36
      Atmospheric amines - Part I. A review
      Ge, Xinlei; Wexler, Anthony S.; Clegg, Simon L.
      Atmospheric Environment (2011), 45 (3), 524-546CODEN: AENVEQ; ISSN:1352-2310. (Elsevier Ltd.)
      A review presenting the current knowledge of atmospherically-relevant amines with respect to their sources, fluxes, and dynamics, including gas-phase reactions, gas-to-particle conversion, and deposition, is given. Health effects of aliph. and arom. amines are briefly summarized as are the atm. occurrence and reactivity of amino acids and urea. Topics discussed include: atm. sources (anthropogenic [animal husbandry, industry and combustion, composting operations, automobiles, other human activities], natural sources [ocean, biomass burning, vegetation, geol. sources]); estd. global flux and ambient concns.; atm. behavior (gas-phase reactions [oxidn., nitrosamines], gas/particle conversion [particulate amines, acid-base chem.], surface deposition); health effects (aliph. amines and amides, arom. amines); amino acids and urea (atm. occurrence and reactivity); and summary.
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    37. 37
      Ohtani, N.; Ohta, T.; Hosoda, Y.; Yamashita, T. Phase Behavior and Phase-Transfer Catalysis of Tetrabutylammonium Salts. Interface-Mediated Catalysis. Langmuir 2004, 20 (2), 409– 415,  DOI: 10.1021/la035462f
      37
      Phase Behavior and Phase-Transfer Catalysis of Tetrabutylammonium Salts. Interface-Mediated Catalysis
      Ohtani, Noritaka; Ohta, Tomoaki; Hosoda, Yasuhiro; Yamashita, Tsuyoshi
      Langmuir (2004), 20 (2), 409-415CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)
      The phase behavior and component compn. of the coexisting phases in the tetrabutylammonium bromide (TBABr)/benzene/water/NaBr four-component system were strongly influenced by the temp., TBABr content, and NaBr concn. The phase-transfer catalytic activity of TBABr for the reaction of decyl methanesulfonate with sodium bromide was closely related to the phase behavior. Under O (oil-rich phase) + L (TBABr-rich liq. phase) + W (aq. phase) triphase conditions, the influences of temp. and stirring speed on the phase-transfer catalytic activity were small compared with those under O + W biphase conditions. The addn. of other quaternary salts that were able to form w/o aggregates in the O phase enhanced the TBABr catalytic activity even under O + W conditions. The relationship between phase behavior and catalytic activity of tetrabutylammonium chloride or iodide (TBACl or TBAI) was also examd. The results strongly suggested that the catalysis of TBAX was attributable to the interfacial reactions of TBAX with the substrate. The interface includes the water-oil microinterface formed in the microemulsion-like L phase as well as the bulk water-oil interface.
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    38. 38
      Winter, B.; Weber, R.; Schmidt, P. M.; Hertel, I. V.; Faubel, M.; Vrbka, L.; Jungwirth, P. Molecular Structure of Surface-Active Salt Solutions: Photoelectron Spectroscopy and Molecular Dynamics Simulations of Aqueous Tetrabutylammonium Iodide. J. Phys. Chem. B 2004, 108 (38), 14558– 14564,  DOI: 10.1021/jp0493531
      38
      Molecular Structure of Surface-Active Salt Solutions: Photoelectron Spectroscopy and Molecular Dynamics Simulations of Aqueous Tetrabutylammonium Iodide
      Winter, Bernd; Weber, Ramona; Schmidt, Philipp M.; Hertel, Ingolf V.; Faubel, Manfred; Vrbka, Lubos; Jungwirth, Pavel
      Journal of Physical Chemistry B (2004), 108 (38), 14558-14564CODEN: JPCBFK; ISSN:1520-6106. (American Chemical Society)
      We report photoelectron measurements and mol. dynamics (MD) simulations with a polarizable force field of surface-active tetrabutylammonium iodide (TBAI) in aq. soln. Photoemission is studied for a photon energy of 100 eV, using a 6-μm-diam. liq. jet. Surfactant activity of the TBAI salt at the soln. surface is proved by a dramatic (×70) increase of the I-(4d) signal, as compared to that of a NaI aq. soln. for identical salt concns. Completion of the segregation monolayer is suggested through the growth of the iodide photoelectron emission signal, as a function of the salt concn. Our expts. reveal identical electron binding energies of iodide in TBAI and NaI aq. solns., which are independent of the salt concn. Zero or very small spectral shifts of any feature, including the low-energy cutoff, suggest that no dipole is formed by TBA+ and I- ion pairs perpendicular to the surface, which is in accord with the simulated ionic d. profiles. Both cations and anions exhibit strong surfactant activity, thus failing to form a strong elec. double layer. While the cations are surface-bound due to hydrophobic interactions, iodide is driven to the vacuum/water interface by its large polarizability. MD simulations also allow characterization of the thermally averaged geometries of the surface-active cations, in particular the orientations of the Bu chains with respect to the water surface.
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    39. 39
      Winter, B.; Weber, R.; Hertel, I. V.; Faubel, M.; Vrbka, L.; Jungwirth, P. Effect of bromide on the interfacial structure of aqueous tetrabutylammonium iodide: Photoelectron spectroscopy and molecular dynamics simulations. Chem. Phys. Lett. 2005, 410 (4), 222– 227,  DOI: 10.1016/j.cplett.2005.05.084
      39
      Effect of bromide on the interfacial structure of aqueous tetrabutylammonium iodide: Photoelectron spectroscopy and molecular dynamics simulations
      Winter, Bernd; Weber, Ramona; Hertel, Ingolf V.; Faubel, Manfred; Vrbka, Lubos; Jungwirth, Pavel
      Chemical Physics Letters (2005), 410 (4-6), 222-227CODEN: CHPLBC; ISSN:0009-2614. (Elsevier B.V.)
      Solvation of surface-active tetrabutylammonium iodide (TBAI) in liq. water and in NaBr aq. soln. was investigated by VUV photoelectron spectroscopy and by mol. dynamics simulations. The obsd. signal intensity changes in the photoemission spectra are consistent with the varying propensities of the different ions for the soln. interface. While the cations are surface-bound due to hydrophobic interactions, the anions are driven to the vacuum/soln. interface by their large polarizability and size. Iodide is more polarizable, and hence more surface-active than bromide, which explains the relatively small decrease of the iodide photoemission signal when TBAI is dissolved in bromide soln.
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    40. 40
      Karashima, S.; Suzuki, T. Charge-Transfer-to-Solvent Reaction in a Hydrophobic Tetrabutylammonium Iodide Molecular Layer in Aqueous Solution. J. Phys. Chem. B 2019, 123 (17), 3769– 3775,  DOI: 10.1021/acs.jpcb.8b12210
      40
      Charge-Transfer-to-Solvent Reaction in a Hydrophobic Tetrabutylammonium Iodide Molecular Layer in Aqueous Solution
      Karashima, Shutaro; Suzuki, Toshinori
      Journal of Physical Chemistry B (2019), 123 (17), 3769-3775CODEN: JPCBFK; ISSN:1520-5207. (American Chemical Society)
      We present ultrafast photoelectron spectroscopy of the charge-transfer-to-solvent reaction in a segregated TBAI (tetrabutylammonium iodide) mol. layer in aq. soln. The reaction times and electron binding energies of transient species vary with TBAI concn. from a very low value of 1 × 10-3 mol L-1, which is in contrast to NaI soln. exhibiting no concn. (0.01-1.0 mol L-1) dependence. The result from soft X-ray N(1s) spectroscopy indicates that the photoelectron intensity in TBAI aq. soln. is about 70 times enhanced as compared to that in NH4Cl aq. soln. for an identical salt concn., and TBA+ drags I- to the surface region. At high TBAI concns., electrons released from I- are trapped and held in the TBAI mol. layer owing to electrostatic attraction by TBA+.
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    41. 41
      Watanabe, I.; Takahashi, N.; Tanida, H. Dehydration of iodide segregated by tetraalkylammonium at the air/solution interface studied by photoelectron emission spectroscopy. Chem. Phys. Lett. 1998, 287 (5), 714– 718,  DOI: 10.1016/S0009-2614(98)00231-0
      41
      Dehydration of iodide segregated by tetraalkylammonium at the air/solution interface studied by photoelectron emission spectroscopy
      Watanabe, Iwao; Takahashi, Naoko; Tanida, Hajime
      Chemical Physics Letters (1998), 287 (5,6), 714-718CODEN: CHPLBC; ISSN:0009-2614. (Elsevier Science B.V.)
      Photoelectron emission spectroscopy was used to detect iodide anion at the aq. soln. surface. The photoelectron emission threshold energies Et for the iodide segregated by tetraalkylammonium cations differ from those for solns. with surface inactive cations. The smaller Et values found for larger alkylammonium salt solns. seem to be due to dehydration of iodide at the surface layer. When tetrabutylammonium is used as the surfactant, the dehydration proceeds in a stepwise way with increasing bulk concn.
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    42. 42
      Sobyra, T. B.; Pliszka, H.; Bertram, T. H.; Nathanson, G. M. Production of Br2 from N2O5 and Br– in Salty and Surfactant-Coated Water Microjets. J. Phys. Chem. A 2019, 123 (41), 8942– 8953,  DOI: 10.1021/acs.jpca.9b04225
      42
      Production of Br2 from N2O5 and Br- in Salty and Surfactant-Coated Water Microjets
      Sobyra, Thomas B.; Pliszka, Helena; Bertram, Timothy H.; Nathanson, Gilbert M.
      Journal of Physical Chemistry A (2019), 123 (41), 8942-8953CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)
      Gas-liq. scattering expts. are used to investigate the oxidn.-redn. reaction N2O5(g) + 2Br-(aq) → Br2(g) + NO3-(aq) + NO2-(aq), a model for the nighttime absorption of N2O5 into aerosol droplets contg. halide ions. The detection of evapg. Br2 mols. provides our first observation of a gaseous reaction product generated by a water microjet in vacuum. N2O5 mols. are directed at a 35 μm diam. jet of 6 or 8 m LiBr in water at 263 or 240 K, followed by detection of both unreacted N2O5 and product Br2 mols. by velocity-resolved mass spectrometry. The N2O5 reaction probability at near-thermal collision energy is too small to be measured and likely lies below 0.2. However, the evapg. Br2 product can be detected and controlled by the presence of surfactants. The addn. of 0.02 m 1-butanol, which creates ∼40% of a compact monolayer, reduces Br2 prodn. by 35%. Following earlier studies, this redn. may be attributed to surface butanol mols. that block N2O5 entry or alter the near-surface distribution of Br-. Remarkably, addn. of the cationic surfactant tetrabutylammonium bromide (TBABr) at 0.005 m (9% of a monolayer) reduces the Br2 signal by 85%, and a 0.050 m soln. (58% of a monolayer) causes the Br2 signal to disappear entirely. A detailed anal. suggests that TBA+ efficiently suppresses Br2 evapn. because it tightly bonds to the Br3- intermediate formed in the highly concd. Br- soln. and thereby hinders the rapid release and evapn. of Br2.
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    43. 43
      Shaloski, M. A.; Gord, J. R.; Staudt, S.; Quinn, S. L.; Bertram, T. H.; Nathanson, G. M. Reactions of N2O5 with Salty and Surfactant-Coated Glycerol: Interfacial Conversion of Br– to Br2 Mediated by Alkylammonium Cations. J. Phys. Chem. A 2017, 121 (19), 3708– 3719,  DOI: 10.1021/acs.jpca.7b02040
      43
      Reactions of N2O5 with Salty and Surfactant-Coated Glycerol: Interfacial Conversion of Br- to Br2 Mediated by Alkylammonium Cations
      Shaloski, Michael A.; Gord, Joseph R.; Staudt, Sean; Quinn, Sarah L.; Bertram, Timothy H.; Nathanson, Gilbert M.
      Journal of Physical Chemistry A (2017), 121 (19), 3708-3719CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)
      Gas-liq. scattering and product-yield expts. are used to investigate reactions of N2O5 with glycerol contg. Br- and surfactant ions. N2O5 oxidizes Br- to Br2 for every soln. tested: 2.7 M NaBr, 0.03 M tetrahexylammonium bromide (THABr), 0.03 M THABr + 0.5 M NaBr, 0.03 M THABr + 0.5 M NaCl, 0.03 M THABr + 0.01 M sodium dodecyl sulfate (SDS), and 0.01 M cetyltrimethylammonium bromide (CTABr). N2O5 also reacts with glycerol itself to produce mono- and dinitroglycerin. Surface tension measurements indicate that 0.03 M THABr and 2.7 M NaBr have similar interfacial Br- concns., though their bulk Br- concns. differ by 90-fold. We find that twice as much Br2 is produced in the presence of THA+, implying that the conversion of Br- to Br2 is initiated at the interface, perhaps mediated by the charged, hydrophobic pocket within the surface THA+ cation. The addn. of 0.5 M NaBr, 0.5 M NaCl, or 0.01 M SDS to 0.03 M THABr lowers the Br2 prodn. rate by 23%, 63%, and 67% of the THABr value, resp. When CTA+ is substituted for THA+, Br2 prodn. drops to 12% of the THABr value. The generation of Br2 under such different conditions implies that trace amts. of surface-active alkylammonium ions can catalyze interfacial N2O5 reactions, even when salts and other surfactants are present.
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    44. 44
      Flechsig, U.; Nolting, F.; Fraile Rodriguez, A.; Krempasky, J.; Quitmann, C.; Schmidt, T.; Spielmann, S.; Zimoch, D.; Garrett, R.; Gentle, I.; Nugent, K.; Wilkins, S. Performance Measurements at the SLS SIM Beamline. AIP Conf. Proc. 2009, 1234, 319– 322,  DOI: 10.1063/1.3463200
      There is no corresponding record for this reference.
    45. 45
      Brown, M. A.; Redondo, A. B.; Jordan, I.; Duyckaerts, N.; Lee, M.-T.; Ammann, M.; Nolting, F.; Kleibert, A.; Huthwelker, T.; Mächler, J.-P.; Birrer, M.; Honegger, J.; Wetter, R.; Wörner, H. J.; Bokhoven, J. A. v. A new endstation at the Swiss Light Source for ultraviolet photoelectron spectroscopy, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy measurements of liquid solutions. Rev. Sci. Instrum. 2013, 84 (7), 073904,  DOI: 10.1063/1.4812786
      46
      A new endstation at the Swiss Light Source for ultraviolet photoelectron spectroscopy, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy measurements of liquid solutions
      Brown, Matthew A.; Redondo, Amaia Beloqui; Jordan, Inga; Duyckaerts, Nicolas; Lee, Ming-Tao; Ammann, Markus; Nolting, Frithjof; Kleibert, Armin; Huthwelker, Thomas; Maechler, Jean-Pierre; Birrer, Mario; Honegger, Juri; Wetter, Reto; Woerner, Hans Jakob; van Bokhoven, Jeroen A.
      Review of Scientific Instruments (2013), 84 (7), 073904/1-073904/8CODEN: RSINAK; ISSN:0034-6748. (American Institute of Physics)
      A new liq. microjet endstation designed for UV (UPS) and x-ray (XPS) photoelectron, and partial electron yield X-ray absorption (XAS) spectroscopies at the Swiss Light Source is presented. The new endstation, which is based on a Scienta HiPP-2 R4000 electron spectrometer, is the 1st liq. microjet endstation capable of operating in vacuum and in ambient pressures up to the equil. vapor pressure of liq. H2O at room temp. The Scienta HiPP-2 R4000 energy analyzer of this new endstation allows for XPS measurements up to 7000 eV electron kinetic energy that will enable electronic structure measurements of bulk solns. and buried interfaces from liq. microjet samples. The endstation is designed to operate at the soft x-ray SIM beamline and at the tender X-ray Phoenix beamline. The endstation can also be operated using a Scienta 5 K UV He lamp for dedicated UPS measurements at the vapor-liq. interface using either He I or He II α lines. The design concept, 1st results from UPS, soft x-ray XPS, and partial electron yield XAS measurements, and an outlook to the potential of this endstation are presented. (c) 2013 American Institute of Physics.
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    46. 46
      Winter, B.; Weber, R.; Widdra, W.; Dittmar, M.; Faubel, M.; Hertel, I. V. Full Valence Band Photoemission from Liquid Water Using EUV Synchrotron Radiation. J. Phys. Chem. A 2004, 108 (14), 2625– 2632,  DOI: 10.1021/jp030263q
      47
      Full Valence Band Photoemission from Liquid Water Using EUV Synchrotron Radiation
      Winter, B.; Weber, R.; Widdra, W.; Dittmar, M.; Faubel, M.; Hertel, I. V.
      Journal of Physical Chemistry A (2004), 108 (14), 2625-2632CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)
      The valence band photoelectron spectra of liq. water (H2O and D2O) are studied in the photon energy range from hν = 60 to 120 eV. The expts. use a 6 μm diam. liq.-jet free vacuum surface at the MBI undulator beamline of the synchrotron radiation facility BESSY. Photoelectron emission from all four valence MOs is obsd. In comparison to those of the gas phase, the peaks are significantly broadened and shifted to lower binding energies by about 1.5 eV. This is attributed primarily to the electronic polarization of the solvent mols. around an ionized water mol. Energy shifts, peak broadening, and relative peak intensities for the four MOs differ because of their specific participation in the hydrogen bonding in liq. water. Relative photoionization cross sections for MOs were measured for hν = 60, 80, and 100 eV. The main difference for liq. water, as compared to the gas phase, is the relative intensity decrease of the 1b2 and 3a1 orbitals, reflecting changes of the MOs due to H-bonding.
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    47. 47
      Yeh, J. J.; Lindau, I. Atomic subshell photoionization cross sections and asymmetry parameters: 1 ⩽ Z ⩽ 103. At. Data Nucl. Data Tables 1985, 32 (1), 1– 155,  DOI: 10.1016/0092-640X(85)90016-6
      48
      Atomic subshell photoionization cross sections and asymmetry parameters: 1 ≤ Z ≤ 103
      Yeh, J. J.; Lindau, I.
      Atomic Data and Nuclear Data Tables (1985), 32 (1), 1-155CODEN: ADNDAT; ISSN:0092-640X.
      At. subshell photoionization cross sections and asymmetry parameters are calcd. with the Hartree-Fock-Slater one-electron central potential model (dipole approxn.) for all elements Z = 1-103. The cross-section results are plotted for all subshells in the energy region 0-1500 eV, and cross sections and asymmetry parameters are tabulated for selected energies in the region 10.2-8047.8 eV. In addn., more detailed graphs are given for the 4d (Z = 39-71) and 5d (Z = 64-100) subshell cross sections in the vicinity of the Cooper min. These data should be particularly useful for work based on spectroscopic investigations of at. subshells using synchrotron radiation and/or discrete line sources.
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    48. 48
      Ottosson, N.; Faubel, M.; Bradforth, S. E.; Jungwirth, P.; Winter, B. Photoelectron spectroscopy of liquid water and aqueous solution: Electron effective attenuation lengths and emission-angle anisotropy. J. Electron Spectrosc. Relat. Phenom. 2010, 177 (2–3), 60– 70,  DOI: 10.1016/j.elspec.2009.08.007
      49
      Photoelectron spectroscopy of liquid water and aqueous solution: Electron effective attenuation lengths and emission-angle anisotropy
      Ottosson, Niklas; Faubel, Manfred; Bradforth, Stephen E.; Jungwirth, Pavel; Winter, Bernd
      Journal of Electron Spectroscopy and Related Phenomena (2010), 177 (2-3), 60-70CODEN: JESRAW; ISSN:0368-2048. (Elsevier B.V.)
      Photoelectron (PE) spectroscopy measurements from liq. water and from a 4 m NaI aq. soln. are performed using a liq. microjet in combination with soft X-ray synchrotron radiation. From the oxygen 1s PE signal intensity from liq. water, measured as a function of photon energy (up to 1500 eV), we quant. det. relative electron inelastic effective attenuation lengths (EAL) for (photo)electron kinetic energies in the 70-900 eV range. In order to det. the abs. electron escape depths a calibration point is needed, which is not directly accessible by expt. This information can instead be indirectly derived by comparing PE expts. and mol. dynamics (MD) simulations of an aq. soln. interface where d. profiles of water, anions, and cations are distinctively different. We have chosen sodium iodide in water because iodide has a considerable propensity for the soln. surface, whereas the sodium cation is repelled from the surface. By measuring the intensities of photoelectrons emitted from different orbitals of different symmetries from each aq. ion we also evaluate whether gas-phase ionization cross sections and asymmetry parameters can describe the photoemission from ions at and near the aq. soln./vapor interface. We show that gas-phase data reproduce surprisingly well the exptl. observations for hydrated ions as long as the photon energy is sufficiently far above the ionization threshold. Electrons detected at the higher photon energies originate predominantly from deeper layers, suggesting that bulk-soln. electron elastic scattering is relatively weak.
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    49. 49
      Schneider, S. R.; Lakey, P. S. J.; Shiraiwa, M.; Abbatt, J. P. D. Reactive Uptake of Ozone to Simulated Seawater: Evidence for Iodide Depletion. J. Phys. Chem. A 2020, 124 (47), 9844– 9853,  DOI: 10.1021/acs.jpca.0c08917
      50
      Reactive uptake of ozone to simulated seawater: Evidence for iodide depletion
      Schneider, Stephanie R.; Lakey, Pascale S. J.; Shiraiwa, Manabu; Abbatt, Jonathan P. D.
      Journal of Physical Chemistry A (2020), 124 (47), 9844-9853CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)
      The reaction of ozone with iodide in the ocean is a major ozone dry deposition pathway, as well as an important source of reactive iodine to the marine troposphere. Few prior lab. expts. have been conducted with environmentally relevant ozone mixing ratios and iodide concns., leading to uncertainties in the rate of the reaction under marine boundary layer conditions. As well, there remains disagreement in the literature assessment of the relative contributions of an interfacial reaction via ozone adsorbed to the ocean surface vs. a bulk reaction with dissolved ozone. In this study, we measure the uptake coeff. of ozone over a buffered, pH 8 salt soln. replicating the concns. of iodide, bromide, and chloride in the ocean over an ozone mixing ratio of 60-500 ppb. Due to iodide depletion in the soln., the measured ozone uptake coeff. is dependent on the exposure time of the soln. to ozone and its mixing ratio. A kinetic multilayer model confirms that iodide depletion is occurring not only within ozone's reactodiffusive depth, which is on the order of microns for environmental conditions, but also deeper into the soln. as well. Best model-measurement agreement arises when some degree of nondiffusive mixing is occurring in the soln., transporting iodide from deeper in the soln. to a thin, diffusively mixed upper layer. If such mixing occurs rapidly in the environment, iodide depletion is unlikely to reduce ozone dry deposition rates. Unrealistically high bulk-to-interface partitioning of iodide is required for the model to predict a substantial interfacial component to the reaction, indicating that the Langmuir-Hinshelwood mechanism is not dominant under environmental conditions.
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    50. 50
      Pruyne, J. G.; Lee, M.-T.; Fábri, C.; Beloqui Redondo, A.; Kleibert, A.; Ammann, M.; Brown, M. A.; Krisch, M. J. Liquid–Vapor Interface of Formic Acid Solutions in Salt Water: A Comparison of Macroscopic Surface Tension and Microscopic in Situ X-ray Photoelectron Spectroscopy Measurements. J. Phys. Chem. C 2014, 118 (50), 29350– 29360,  DOI: 10.1021/jp5056039
      51
      Liquid-vapor interface of formic acid solutions in salt water: A comparison of macroscopic surface tension and microscopic in situ x-ray photoelectron spectroscopy measurement
      Pruyne, Jefferson G.; Lee, Ming-Tao; Fabri, Csaba; Beloqui Redondo, Amaia; Kleibert, Armin; Ammann, Markus; Brown, Matthew A.; Krisch, Maria J.
      Journal of Physical Chemistry C (2014), 118 (50), 29350-29360CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)
      The liq.-vapor interface is difficult to access exptl. but is of interest from a theor. and applied point of view and has particular importance in atm. aerosol chem. Here we examine the liq.-vapor interface for mixts. of water, sodium chloride, and formic acid, an abundant chem. in the atm. We compare the results of surface tension and XPS measurements over a wide range of formic acid concns. Surface tension measurements provide a macroscopic characterization of solns. ranging from 0 to 3 M sodium chloride and from 0 to over 0.5 mol fraction formic acid. Sodium chloride was found to be a weak salting out agent for formic acid with surface excess depending only slightly on salt concn. In situ XPS provides a complementary mol. level description about the liq.-vapor interface. XPS measurements over an exptl. probe depth of 51 Å gave the C 1s to O 1s ratio for both total oxygen and oxygen from water. XPS also provides detailed electronic structure information that is inaccessible by surface tension. D. functional theory calcns. were performed to understand the obsd. shift in C 1s binding energies to lower values with increasing formic acid concn. Part of the exptl. -0.2 eV shift can be assigned to the soln. compn. changing from predominantly monomers of formic acid to a combination of monomers and dimers; however, the lack of an appropriate ref. to calibrate the abs. BE scale at high formic acid mole fraction complicates the interpretation. Our data are consistent with surface tension measurements yielding a significantly more surface sensitive measurement than XPS due to the relatively weak propensity of formic acid for the interface. A simple model allowed us to replicate the XPS results under the assumption that the surface excess was contained in the top four angstroms of soln.
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    51. 51
      Lee, M.-T.; Orlando, F.; Artiglia, L.; Chen, S.; Ammann, M. Chemical Composition and Properties of the Liquid–Vapor Interface of Aqueous C1 to C4 Monofunctional Acid and Alcohol Solutions. J. Phys. Chem. A 2016, 120 (49), 9749– 9758,  DOI: 10.1021/acs.jpca.6b09261
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      Chemical Composition and Properties of the Liquid-Vapor Interface of Aqueous C1 to C4 Monofunctional Acid and Alcohol Solutions
      Lee, Ming-Tao; Orlando, Fabrizio; Artiglia, Luca; Chen, Shuzhen; Ammann, Markus
      Journal of Physical Chemistry A (2016), 120 (49), 9749-9758CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)
      The liq.-vapor interface is playing an important role in aerosol and cloud chem. in cloud droplet activation by aerosol particles and potentially also in ice nucleation. The authors have employed the surface sensitive and chem. selective XPS technique to examine the liq.-vapor interface for mixts. of water and small alcs. or small carboxylic acids (C1 to C4), abundant chems. in the atm. in concn. ranges relevant for cloud chem. or aerosol particles at the point of activation into a cloud droplet. A linear correlation was found between the headgroup carbon 1s core-level signal intensity and the surface excess derived from literature surface tension data with the offset being explained by the bulk contribution to the photoemission signal. The relative interfacial enhancement of the carboxylic acids over the carboxylates at the same bulk concn. is highest (nearly 20) for propionic acid/propionate and still ∼5 for formic acid/formate, also in fair agreement with surface tension measurements. This provides direct spectroscopic evidence for high carboxylic acid concns. at aq. soln.-air interfaces that may be responsible for acid catalyzed chem. under moderately acidic conditions with respect to their bulk aq. phase acidity const. By assessing the ratio of aliph. to headgroup C 1s signal intensities XPS also provides information about the orientation of the mols. The results indicate an increasing orientation of alcs. and neutral acids toward the surface normal as a function of chain length, along with increasing importance of lateral hydrophobic interactions at higher surface coverage. In turn, the carboxylate ions exhibit stronger orientation toward the surface normal than the corresponding neutral acids, likely caused by the stronger hydration of the charged headgroup.
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    52. 52
      Walz, M. M.; Werner, J.; Ekholm, V.; Prisle, N. L.; Öhrwall, G.; Björneholm, O. Alcohols at the aqueous surface: chain length and isomer effects. Phys. Chem. Chem. Phys. 2016, 18 (9), 6648– 6656,  DOI: 10.1039/C5CP06463E
      53
      Alcohols at the aqueous surface: chain length and isomer effects
      Walz, M.-M.; Werner, J.; Ekholm, V.; Prisle, N. L.; Oehrwall, G.; Bjoerneholm, O.
      Physical Chemistry Chemical Physics (2016), 18 (9), 6648-6656CODEN: PPCPFQ; ISSN:1463-9076. (Royal Society of Chemistry)
      Surface-active org. mols. at the liq.-vapor interface are of great importance in atm. science. Therefore, we studied the surface behavior of alc. isomers with different chain lengths (C4-C6) in aq. soln. with surface- and chem. sensitive XPS, which reveals information about the surface structure on a mol. level. Gibbs free energies of adsorption and surface concns. are detd. from the XPS results using a std. Langmuir adsorption isotherm model. The free energies of adsorption, ranging from around -15 to -19 kJ mol-1 (C4-C6), scale linearly with the no. of carbon atoms within the alcs. with ΔGAds per -CH2- ≈ -2 kJ mol-1. While for the linear alcs., surface concns. lie around 2.4 × 1014 mols. per cm2 at the bulk concns. where monolayers are formed, the studied branched alcs. show lower surface concns. of around 1.6 × 1014 mols. per cm2, both of which are in line with the mol. structure and their orientation at the interface. Interestingly, we find that there is a max. in the surface enrichment factor for linear alcs. at low concns., which is not obsd. for the shorter branched alcs. This is interpreted in terms of a cooperative effect, which we suggest to be the result of more effective van der Waals interactions between the linear alc. alkyl chains at the aq. surface, making it energetically even more favorable to reside at the liq.-vapor interface.
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    53. 53
      Toribio, A. R.; Prisle, N. L.; Wexler, A. S. Statistical Mechanics of Multilayer Sorption: Surface Concentration Modeling and XPS Measurement. J. Phys. Chem. Lett. 2018, 9 (6), 1461– 1464,  DOI: 10.1021/acs.jpclett.8b00332
      54
      Statistical Mechanics of Multilayer Sorption: Surface Concentration Modeling and XPS Measurement
      Toribio, Anthony R.; Prisle, Noenne L.; Wexler, Anthony S.
      Journal of Physical Chemistry Letters (2018), 9 (6), 1461-1464CODEN: JPCLCD; ISSN:1948-7185. (American Chemical Society)
      The concn. of solute mols. at the surface of a liq. is a factor in heterogeneous reactions, surface tension, and Marangoni-effect-driven surface flows. Increasingly, XPS has enabled surface concns. to be measured. In prior work, the authors employed statistical mechanics to derive expressions for surface tension as a function of solute activity in a binary soln. Here the authors use a Gibbs relation to derive concomitant expressions for surface concn. Surface tension data from the literature for 5 alcs. are used to identify parameters in the surface tension equation. These parameters are then used in the surface concn. equation to predict surface concns. Comparison of these predictions to those measured with XPS shows a factor of 3 difference between measured and predicted surface concns. Potential reasons for the discrepancy are discussed, including lack of surface-bulk equil. in the measurements.
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    54. 54
      Ottosson, N.; Wernersson, E.; Söderström, J.; Pokapanich, W.; Kaufmann, S.; Svensson, S.; Persson, I.; Öhrwall, G.; Björneholm, O. The protonation state of small carboxylic acids at the water surface from photoelectron spectroscopy. Phys. Chem. Chem. Phys. 2011, 13 (26), 12261– 12267,  DOI: 10.1039/c1cp20245f
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      The protonation state of small carboxylic acids at the water surface from photoelectron spectroscopy
      Ottosson, Niklas; Wernersson, Erik; Soederstroem, Johan; Pokapanich, Wandared; Kaufmann, Susanna; Svensson, Svante; Persson, Ingmar; Oehrwall, Gunnar; Bjoerneholm, Olle
      Physical Chemistry Chemical Physics (2011), 13 (26), 12261-12267CODEN: PPCPFQ; ISSN:1463-9076. (Royal Society of Chemistry)
      We report highly surface sensitive core-level photoelectron spectra of small carboxylic acids (formic, acetic and butyric acid) and their resp. carboxylate conjugate base forms (formate, acetate and butyrate) in aq. soln. The relative surface propensity of the carboxylic acids and carboxylates is obtained by monitoring their resp. C1s signal intensities from a soln. in which their bulk concns. are equal. All the acids are found to be enriched at the surface relative to the corresponding carboxylates. By monitoring the PE signals of acetic acid and acetate as a function of total concn., we find that the protonation of acetic acid is nearly complete in the interface layer. This is in agreement with literature surface tension data, from which it is inferred that the acids are enriched at the surface while (sodium) formate and acetate, but not butyrate, are depleted. For butyric acid, we conclude that the carboxylate form co-exists with the acid in the interface layer. The free energy cost of replacing an adsorbed butyric acid mol. with a butyrate ion at 1.0 M concn. is estd. to be >5 kJ mol-1. By comparing concn. dependent surface excess data with the evolution of the corresponding photoemission signals it is furthermore possible to draw conclusions about how the distribution of mols. that contribute to the excess is altered with bulk concn.
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    55. 55
      Bhowmik, D.; Malikova, N.; Mériguet, G.; Bernard, O.; Teixeira, J.; Turq, P. Aqueous solutions of tetraalkylammonium halides: ion hydration, dynamics and ion–ion interactions in light of steric effects. Phys. Chem. Chem. Phys. 2014, 16 (26), 13447– 13457,  DOI: 10.1039/C4CP01164C
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      Aqueous solutions of tetraalkylammonium halides: ion hydration, dynamics and ion-ion interactions in light of steric effects
      Bhowmik, Debsindhu; Malikova, Natalie; Meriguet, Guillaume; Bernard, Olivier; Teixeira, Jose; Turq, Pierre
      Physical Chemistry Chemical Physics (2014), 16 (26), 13447-13457CODEN: PPCPFQ; ISSN:1463-9076. (Royal Society of Chemistry)
      Mol. simulations have allowed us to probe the at. details of aq. solns. of tetramethylammonium (TMA) and tetrabutylammonium (TBA) bromide, across a wide range of concns. (0.5 to 3-4 m). We highlight the space-filling (TMA+) vs. penetrable (TBA+) nature of these polyat. cations and its consequence for ion hydration, ion dynamics and ion-ion interactions. A well-established hydration is seen for both TMA+ and TBA+ throughout the concn. range studied. A clear penetration of water mols., as well as counterions, between the hydrocarbon arms of TBA+, which remain in an extended configuration, is seen. Global rotation of individual TBA+ points towards isolated rather than aggregated ions (from dil. up to 1 m concn.). Only for highly concd. solns., in which inter-penetration of adjacent TBA+s cannot be avoided, does the rotational time increase dramatically. From both structural and dynamic data we conclude that there is absence of hydrophobicity-driven cation-cation aggregation in both TMABr and TBABr solns. studied. The link between these real systems and the theor. predictions for spherical hydrophobic solutes of varying size does not seem straightforward.
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    56. 56
      Shah, A.-u.-H. A.; Ali, K.; Bilal, S. Surface tension, surface excess concentration, enthalpy and entropy of surface formation of aqueous salt solutions. Colloids Surf., A 2013, 417, 183– 190,  DOI: 10.1016/j.colsurfa.2012.10.054
      57
      Surface tension, surface excess concentration, enthalpy and entropy of surface formation of aqueous salt solutions
      Shah, Anwar-ul-Haq Ali; Ali, Khurshid; Bilal, Salma
      Colloids and Surfaces, A: Physicochemical and Engineering Aspects (2013), 417 (), 183-190CODEN: CPEAEH; ISSN:0927-7757. (Elsevier B.V.)
      Surface tensions of aq. solns. of sodium salts of chloride, bromide and nitrate; potassium salts of chloride, bromide and nitrate; lithium chloride and potassium iodide has been detd. exptl. at different concns. and temps. ranging from 0.10 to 2.00 mol kg-1 and 10-30 °C, resp. Concn. and temp. dependence of the surface tension of the selected salts has been studied for further estn. of surface excess concn., enthalpy and entropy of surface formation. The results show that the surface excess concn. decreases linearly with concn. but remains almost const. with the variations of temp. Similarly the enthalpy of surface formation was obsd. to decrease with concn. but remained almost const. with the change in temp. The entropy of surface formation was found to decrease with concn. in most cases.
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    57. 57
      Ottosson, N.; Vácha, R.; Aziz, E. F.; Pokapanich, W.; Eberhardt, W.; Svensson, S.; Öhrwall, G.; Jungwirth, P.; Björneholm, O.; Winter, B. Large variations in the propensity of aqueous oxychlorine anions for the solution/vapor interface. J. Chem. Phys. 2009, 131 (12), 124706,  DOI: 10.1063/1.3236805
      58
      Large variations in the propensity of aqueous oxychlorine anions for the solution/vapor interface
      Ottosson, Niklas; Vacha, Robert; Aziz, Emad F.; Pokapanich, Wandared; Eberhardt, Wolfgang; Svensson, Svante; Oehrwall, Gunnar; Jungwirth, Pavel; Bjoerneholm, Olle; Winter, Bernd
      Journal of Chemical Physics (2009), 131 (12), 124706/1-124706/7CODEN: JCPSA6; ISSN:0021-9606. (American Institute of Physics)
      Core-level photoelectron spectroscopy measurements have been performed of aq. solns. of NaCl co-dissolved with NaClOn (n = 1-4). Each species has a distinct Cl 2p electron binding energy, which can be exploited for depth-profiling expts. to study the competition between Cl- and ClOn- anions for residing in the outermost layers of the soln./vapor interface. Strongest propensity for the surface is obsd. for n = 4 (perchlorate), followed by n = 3 (chlorate), n = 2 (chlorite), n = 0 (chloride), and n = 1 (hypochlorite). Mol. dynamics simulations rationalize the greatest surface propensity of the most oxidized anions in terms of their larger size and polarizability. The anomalous behavior of hypochlorite, being less surface-active than chloride, although it is both larger and more polarizable, is suggested to arise from the charge asymmetry over the anion, increasing its efficiency for bulk solvation. (c) 2009 American Institute of Physics.
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    58. 58
      Olivieri, G.; Parry, K. M.; D’Auria, R.; Tobias, D. J.; Brown, M. A. Specific Anion Effects on Na+ Adsorption at the Aqueous Solution–Air Interface: MD Simulations, SESSA Calculations, and Photoelectron Spectroscopy Experiments. J. Phys. Chem. B 2018, 122 (2), 910– 918,  DOI: 10.1021/acs.jpcb.7b06981
      59
      Specific Anion Effects on Na(+) Adsorption at the Aqueous Solution-Air Interface: MD Simulations, SESSA Calculations, and Photoelectron Spectroscopy Experiments
      Olivieri Giorgia; Brown Matthew A; Parry Krista M; D'Auria Raffaella; Tobias Douglas J
      The journal of physical chemistry. B (2018), 122 (2), 910-918 ISSN:.
      Specific ion effects of the large halide anions have been shown to moderate anion adsorption to the air-water interface (AWI), but little quantitative attention has been paid to the behavior of alkali cations. Here we investigate the concentration and local distribution of sodium (Na(+)) at the AWI in dilute (<1 M) aqueous solutions of NaCl, NaBr, and NaI using a combination of molecular dynamics (MD) and SESSA simulations, and liquid jet ambient pressure photoelectron spectroscopy measurements. We use SESSA to simulate Na 2p photoelectron intensities on the basis of the atom density profiles obtained from MD simulations, and we compare the simulation results with photoelectron spectroscopy experiments to evaluate the performance of a nonpolarizable force field model versus that of an induced dipole polarizable one. Our results show that the nonpolarizable force model developed by Horinek and co-workers (Chem. Phys. Lett. 2009, 479, 173-183) accurately predicts the local concentration and distribution of Na(+) near the AWI for all three electrolytes, whereas the polarizable model does not. To our knowledge, this is the first interface-specific spectroscopic validation of a MD force field. The molecular origins of the unique Na(+) distributions for the three electrolytes are analyzed on the basis of electrostatic arguments, and shown to arise from an indirect anion effect wherein the identity of the anion affects the strength of the attractive Na(+)-H2O electrostatic interaction. Finally, we use the photoelectron spectroscopy results to constrain the range of inelastic mean free paths (IMFPs) for the three electrolyte solutions used in the SESSA simulations that are able to reproduce the experimental intensities. Our results suggest that earlier estimates of IMFPs for aqueous solutions are likely too high.
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    59. 59
      Eschen, F.; Heyerhoff, M.; Morgner, H.; Vogt, J. The concentration-depth profile at the surface of a solution of tetrabutylammonium iodide in formamide, based on angle-resolved photoelectron spectroscopy. J. Phys.: Condens. Matter 1995, 7 (10), 1961– 1978,  DOI: 10.1088/0953-8984/7/10/006
      60
      The concentration-depth profile at the surface of a solution of tetrabutylammonium iodide in formamide, based on angle-resolved photoelectron spectroscopy
      Eschen, F.; Heyerhoff, M.; Morgner, H.; Vogt, J.
      Journal of Physics: Condensed Matter (1995), 7 (10), 1961-78CODEN: JCOMEL; ISSN:0953-8984. (Institute of Physics Publishing)
      We have investigated a soln. of tetrabutylammonium iodide (TBAI) in the polar solvent formamide (FA) using angle-resolved photoelectron spectroscopy at the Berlin Electron Storage Ring for Synchrotron Radiation (BESSY). The concn. was set to 0.5 molality. We have evaluated the signals from C 1s pertaining to TBAI and FA sep., varying the photon energy between 310 and 540 eV as well as the e-emission angle with respect to the surface normal. The combination of these data with earlier results from ARXPS obtained by Siegbahn and co-workers allowed us to establish a concn.-depth profile of the surface-active salt TBAI. For this purpose we have employed a new theor. formulation and developed a new elaborate fitting program based on a genetic algorithm. The concn. of the salt could be followed down to a depth of about 45 Å below the surface. Cross sections for the inelastic energy loss of electrons in the liq. could be established as a function of electron energy. Comparison with conventional surface tension measurements allowed us to derive abs. values for the cross sections.
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    60. 60
      Bergersen, H.; Marinho, R. R. T.; Pokapanich, W.; Lindblad, A.; Björneholm, O.; Sæthre, L. J.; Öhrwall, G. A photoelectron spectroscopic study of aqueous tetrabutylammonium iodide. J. Phys.: Condens. Matter 2007, 19 (32), 326101,  DOI: 10.1088/0953-8984/19/32/326101
      61
      A photoelectron spectroscopic study of aqueous tetrabutylammonium iodide
      Bergersen, H.; Marinho, R. R. T.; Pokapanich, W.; Lindblad, A.; Bjoerneholm, O.; Saethre, L. J.; Oehrwall, G.
      Journal of Physics: Condensed Matter (2007), 19 (32), 326101/1-326101/9CODEN: JCOMEL; ISSN:0953-8984. (Institute of Physics Publishing)
      Photoelectron spectra of Bu4NI (TBAI) dissolved in H2O were recorded using a novel exptl. set-up, which enables photoelectron spectroscopy of volatile liqs. The set-up is described. Ionization energies are reported for I- 5p, I- 4d, C 1s and N 1s. The C 1s spectrum shows evidence of inelastic scattering of the photoelectrons, that differs from the case of TBAI in formamide.
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    61. 61
      Woods, E.; Konys, C. A.; Rossi, S. R. Photoemission of Iodide from Aqueous Aerosol Particle Surfaces. J. Phys. Chem. A 2019, 123 (13), 2901– 2907,  DOI: 10.1021/acs.jpca.8b12323
      62
      Photoemission of iodide from aqueous aerosol particle surfaces
      Woods, Ephraim; Konys, Casey A.; Rossi, Sean R.
      Journal of Physical Chemistry A (2019), 123 (13), 2901-2907CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)
      The photoemission of iodide from aq. aerosol particle surfaces measures the surface concn. of iodide in predominantly supersatd. NaCl aerosol particles. Using the Langmuir model to describe the adsorption to the surface of aq. iodide anions, the std. Gibbs free energy of adsorption is -15 kJ/mol in these systems. The presence of charged surfactants on the particle surfaces changes the adsorption behavior of iodide. The addn. of sodium docecylsulfate (SDS) reduces the coverage of iodide, consistent with a competitive adsorption scenario. For surfaces coated with C12-, C14-, or C16-trimethylammonium chloride, the addn. of iodide results in the formation of iodide-surfactant ion pairs at the surface with enhanced photoemission. The adsorption free energy for iodide in these systems is -21 kJ/mol. The results demonstrate the surface enhancement of iodide in supersatd., atmospherically relevant conditions and demonstrate important differences between single-salt solns. and mixts. in the limit of high concn.
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    62. 62
      Zhao, X.; Nathanson, G. M.; Andersson, G. G. Experimental Depth Profiles of Surfactants, Ions, and Solvent at the Angstrom Scale: Studies of Cationic and Anionic Surfactants and their Salting Out. J. Phys. Chem. B 2020, 124 (11), 2218– 2229,  DOI: 10.1021/acs.jpcb.9b11686
      63
      Experimental Depth Profiles of Surfactants, Ions, and Solvent at the Angstrom Scale: Studies of Cationic and Anionic Surfactants and Their Salting Out
      Zhao, Xianyuan; Nathanson, Gilbert M.; Andersson, Gunther G.
      Journal of Physical Chemistry B (2020), 124 (11), 2218-2229CODEN: JPCBFK; ISSN:1520-5207. (American Chemical Society)
      Neutral impact ion scattering spectroscopy (NICISS) is used to measure the depth profiles of ionic surfactants, counterions, and solvent mols. on the angstrom scale. The chosen surfactants are 0.010 m tetrahexylammonium bromide (THA+/Br-) and 0.0050 m sodium dodecyl sulfate (Na+/DS-) in the absence and presence of 0.30 m NaBr in liq. glycerol. NICISS dets. the depth profiles of the elements C, O, Na, S, and Br through the loss in energy of 5 keV He atoms that travel into and out of the liq., which is then converted into depth. In the absence of NaBr, we find that THA+ and its Br- counterion segregate together because of charge attraction, forming a narrow double layer that is 10 Å wide and 150 times more concd. than in the bulk. With the addn. of NaBr, THA+ is "salted out" to the surface, increasing the interfacial Br- concn. by 3-fold and spreading the anions over a ∼30 Å depth. Added NaBr similarly increases the interfacial concn. of DS- ions and broadens their positions. Conversely, the dissolved Br- ions are significantly depleted over a depth of 0-40 Å from the surface because of charge repulsion from DS- ions within the interfacial region. These different interfacial Br- propensities correlate with previously measured gas-liq. reactivities: gaseous Cl2 readily reacts with Br- ions in the presence of THA+ but drops 70-fold in the presence of DS-, demonstrating that surfactant headgroup charge controls the reactivity of Br- through changes in its depth profile.
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    63. 63
      Walz, M. M.; Caleman, C.; Werner, J.; Ekholm, V.; Lundberg, D.; Prisle, N. L.; Ohrwall, G.; Bjorneholm, O. Surface behavior of amphiphiles in aqueous solution: a comparison between different pentanol isomers. Phys. Chem. Chem. Phys. 2015, 17 (21), 14036– 14044,  DOI: 10.1039/C5CP01870F
      64
      Surface behavior of amphiphiles in aqueous solution: a comparison between different pentanol isomers
      Walz, M.-M.; Caleman, C.; Werner, J.; Ekholm, V.; Lundberg, D.; Prisle, N. L.; Oehrwall, G.; Bjoerneholm, O.
      Physical Chemistry Chemical Physics (2015), 17 (21), 14036-14044CODEN: PPCPFQ; ISSN:1463-9076. (Royal Society of Chemistry)
      Surface-active oxygenated amphiphilic isomers (1- and 3-pentanol) have been compared at the aq. surface with surface- and chem. sensitive XPS, which reveals information about the surface structure on a mol. level. The exptl. data are complemented with mol. dynamics (MD) simulations. A concn.-dependent orientation and solvation of the amphiphiles at the aq. surface is obsd. At bulk concns. as low as around 100 mM, a monolayer starts to form for both isomers, with the hydroxyl groups pointing towards the bulk water and the alkyl chains pointing towards the vacuum. The monolayer (ML) packing d. of 3-pentanol is approx. 70% of the one obsd. for 1-pentanol, with a molar surface concn. that is approx. 90 times higher than the bulk concn. for both mols. The mol. area at ML coverage (≈ 100 mM) was calcd. to be around 32 ± 2 Å2 per mol. for 1-pentanol and around 46 ± 2 Å2 per mol. for 3-pentanol, which results in a higher surface concn. (mols. per cm2) for the linear isomer. In general we conclude therefore that isomers - with comparable surface activities - that have smaller mol. areas will be more abundant at the interface in comparison to isomers with larger mol. areas, which might be of crucial importance for the understanding of key properties of aerosols, such as evapn. and uptake capabilities as well as their reactivity.
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    64. 64
      Ghosal, S.; Brown, M. A.; Bluhm, H.; Krisch, M. J.; Salmeron, M.; Jungwirth, P.; Hemminger, J. C. Ion Partitioning at the Liquid/Vapor Interface of a Multicomponent Alkali Halide Solution: A Model for Aqueous Sea Salt Aerosols. J. Phys. Chem. A 2008, 112 (48), 12378– 12384,  DOI: 10.1021/jp805490f
      65
      Ion Partitioning at the Liquid/Vapor Interface of a Multicomponent Alkali Halide Solution: A Model for Aqueous Sea Salt Aerosols
      Ghosal, Sutapa; Brown, Matthew A.; Bluhm, Hendrik; Krisch, Maria J.; Salmeron, Miquel; Jungwirth, Pavel; Hemminger, John C.
      Journal of Physical Chemistry A (2008), 112 (48), 12378-12384CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)
      The chem. of Br- species assocd. with sea salt ice and aerosols has been implicated in the episodes of ozone depletion reported at Arctic sunrise. However, Br- is only a minor component in sea salt, which has a Br-/Cl- molar ratio of ∼0.0015. Sea salt is a complex mixt. of many different species, with NaCl as the primary component. In recent years exptl. and theor. studies have reported enhancement of the large, more polarizable halide ion at the liq./vapor interface of corresponding aq. alkali halide solns. The proposed enhancement is likely to influence the availability of sea salt Br- for heterogeneous reactions such as those involved in the ozone depletion episodes. We report here ambient pressure XPS studies and mol. dynamics simulations showing direct evidence of Br- enhancement at the interface of an aq. NaCl soln. doped with bromide. The expts. were carried out on samples with Br-/Cl- ratios 0.1-10%, the latter being also the ratio for which simulations were carried out. This is the 1st direct measurement of interfacial enhancement of Br- in a multicomponent soln. with particular relevance to sea salt chem.
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    65. 65
      Toivola, M.; Prisle, N. L.; Elm, J.; Waxman, E. M.; Volkamer, R.; Kurtén, T. Can COSMOTherm Predict a Salting in Effect?. J. Phys. Chem. A 2017, 121 (33), 6288– 6295,  DOI: 10.1021/acs.jpca.7b04847
      66
      Can COSMOTherm Predict a Salting in Effect?
      Toivola, Martta; Prisle, Noenne L.; Elm, Jonas; Waxman, Eleanor M.; Volkamer, Rainer; Kurten, Theo
      Journal of Physical Chemistry A (2017), 121 (33), 6288-6295CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)
      We have used COSMO-RS, a method combining quantum chem. with statistical thermodn., to compute Setschenow consts. (KS) for a large array of org. solutes and salts. These comprise both atmospherically relevant solute-salt combinations, as well as systems for which exptl. data are available. In agreement with previous studies on single salts, the Setschenow consts. predicted by COSMO-RS (as implemented in the COSMOTherm program) are generally too large compared to expts. COSMOTherm overpredicts salting out (pos. KS), and/or underpredicts salting in (neg. KS). For ammonium and sodium salts, KS values are larger for oxalates and sulfates, and smaller for chlorides and bromides. For chloride and bromide salts, KS values usually increase with decreasing size of the cation, along the series Pr4N+ < Et4N+ < Me4N+ ≤ Na+ ≈ NH4+. Of the atmospherically relevant systems studied, salting in is predicted only for oxalic acid in sodium and ammonium oxalate, and sodium sulfate, solns. COSMOTherm was thus unable to replicate the exptl. obsd. salting in of glyoxal in sulfate solns., likely due to the overestimation of salting out effects. By contrast, COSMOTherm does qual. predict the exptl. obsd. salting in of multiple org. solutes in solns. of alkylaminium salts.
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    66. 66
      Endo, S.; Pfennigsdorff, A.; Goss, K.-U. Salting-Out Effect in Aqueous NaCl Solutions: Trends with Size and Polarity of Solute Molecules. Environ. Sci. Technol. 2012, 46 (3), 1496– 1503,  DOI: 10.1021/es203183z
      67
      Salting-Out Effect in Aqueous NaCl Solutions: Trends with Size and Polarity of Solute Molecules
      Endo, Satoshi; Pfennigsdorff, Andrea; Goss, Kai-Uwe
      Environmental Science & Technology (2012), 46 (3), 1496-1503CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
      Salting-out in aq. NaCl solns. is relevant for the environmental behavior of org. contaminants. Setschenow (or salting-out) coeffs. (Ks [M-1]) for 43 diverse neutral compds. in NaCl solns. were measured using a shared headspace passive dosing method and a negligible depletion solid phase microextn. technique. The results were used to calibrate and evaluate estn. models for Ks. The molar volume of the solute correlated only moderately with Ks (R2 =0.49, SD =0.052). The polyparameter linear free energy relation (pp-LFER) model that uses 5 compd. descriptors resulted in a more accurate fit to our data (R2 =0.83, SD =0.031). The pp-LFER anal. revealed that Na+ and Cl- in aq. solns. increase the cavity formation energy cost and the polar interaction energies toward neutral org. solutes. Accordingly, the salting-out effect increases with the size and decreases with the polarity of the solute mol. COSMO-RS, a quantum mechanics-based fully predictive model, generally overpredicted the exptl. Ks, but the predicted values were moderately correlated with the exptl. values (R2 =0.66, SD =0.042). Literature data (n =93) were predicted by the calibrated pp-LFER and COSMO-RS models with root mean squared errors of 0.047 and 0.050, resp. This study offers prediction models to est. Ks, allowing implementation of the salting-out effect in contaminant fate models, linkage of various partition coeffs. (such as air-water, sediment-water, and extn. phase-water partition coeffs.) measured for freshwater and seawater, and estn. of enhancement of extn. efficiency in anal. procedures.
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    67. 67
      Krisch, M. J.; D’Auria, R.; Brown, M. A.; Tobias, D. J.; Hemminger, C.; Ammann, M.; Starr, D. E.; Bluhm, H. The Effect of an Organic Surfactant on the Liquid–Vapor Interface of an Electrolyte Solution. J. Phys. Chem. C 2007, 111 (36), 13497– 13509,  DOI: 10.1021/jp073078b
      68
      The Effect of an Organic Surfactant on the Liquid-Vapor Interface of an Electrolyte Solution
      Krisch, Maria J.; D'Auria, Raffaella; Brown, Matthew A.; Tobias, Douglas J.; Hemminger, John C.; Ammann, Markus; Starr, David E.; Bluhm, Hendrik
      Journal of Physical Chemistry C (2007), 111 (36), 13497-13509CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)
      Insight into ion behavior at mixed org./aq. liq. surfaces is crucial for understanding the chem. of atm. aerosols, which frequently contain mixts. of water, electrolytes, and orgs. The addn. of 1-butanol to an aq. potassium iodide soln. modifies the interfacial profile of ions at the liq.-vapor interface. Our expts. probe at. compn. at the liq. surface with ambient pressure XPS. Photoelectron kinetic energies are varied to produce a depth profile of the liq.-vapor interface. Mol. dynamics simulations of butanol in an aq. electrolyte soln. are used to develop a detailed understanding of the ion-solvent interactions in the interfacial region. Our previous work on pure aq. salt solns. obsd. substantial ion concns. at the liq.-vapor interface and an increased anion/cation ratio at the interface. A question has arisen as to whether covering the surface with an org. monolayer might change or suppress the interfacial ion concns. We observe that the direct interaction of both the cation and the anion with the butanol leads to changes in the ion concns. in the region of the liq. interface. Substantial ion concns. are still obsd. in the interfacial region in the presence of butanol. However, we do find that the presence of the butanol reduces the previously obsd. anion/cation sepn. in the interfacial region.
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    68. 68
      Sawada, K.; Takahashi, E.; Horie, T.; Satoh, K. Solvent Effects on Ion-Pair Distribution and Dimerization of Tetraalkylammonium Salts. Monatsh. Chem. 2001, 132 (11), 1439– 1450,  DOI: 10.1007/s007060170026
      69
      Solvent effects on ion-pair distribution and dimerization of tetraalkylammonium salts
      Sawada, Kiyoshi; Takahashi, Eiji; Horie, Tomokazu; Satoh, Keiichi
      Monatshefte fuer Chemie (2001), 132 (11), 1439-1450CODEN: MOCMB7; ISSN:0026-9247. (Springer-Verlag Wien)
      The distribution of tetraalkylammonium ions (CnH2n+1)4N+ (R+, TAAn+, n = 4-7) with picrate ion (pic-) and inorg. anions X-, (Cl-, Br-, ClO4-), into various inert org. solvents was studied at 25.0 °C. The distribution data were analyzed by taking into consideration the distribution of ion pairs, R+·X-, and the dimerization of the ion pairs, (R+·X-)2, in the org. phase. The ion-pair, distribution const., Kdist, increases with increasing chain length of the tetralkylammonium ion and with increasing ionic radius of the anion. The values of Kdist show a good correlation with the ET value of solvent, i.e. the solvation ability with respect to the anion, and smoothly increase with increasing ET. The effect of the solvent on the dimerization consts., Kdim, is markedly different between the ion pairs of picrate ion and inorg. anions. In the case of picrate, Kdim significantly decreases with decreasing length of the alkyl chain of the tetraalkylammonium ion, but hardly changes by changing the solvent. On the other hand, in the case of ion pairs of inorg. anions the value of Kdim decreases with decreasing ET and is almost const. for all anions. These results were reasonably explained by the difference of the solvation of the anion moieties of the monomeric and dimeric ion pairs.
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    69. 69
      Tomar, P. A.; Kolhapurkar, R. R.; Dagade, D. H.; Patil, K. J. Equilibrium Constant Studies for Complexation between Ammonium Ions and 18-Crown-6 in Aqueous Solutions at 298.15 K. J. Solution Chem. 2007, 36 (2), 193– 209,  DOI: 10.1007/s10953-006-9102-5
      70
      Equilibrium Constant Studies for Complexation between Ammonium Ions and 18-Crown-6 in Aqueous Solutions at 298.15 K
      Tomar, Preeti A.; Kolhapurkar, Rahul R.; Dagade, Dilip H.; Patil, Kesharsingh J.
      Journal of Solution Chemistry (2007), 36 (2), 193-209CODEN: JSLCAG; ISSN:0095-9782. (Springer)
      Osmotic vapor pressure and d. measurements have been carried out for binary aq. and ternary aq. solns. contg. a fixed concn. of 18-crown-6 (0.2 mol/kg-1) and ammonium chloride or ammonium bromide at 298.15 K. The concn. of the ammonium salts was varied between 0.02 to 0.5 mol/kg-1. The measured water activities were used to obtain the activity coeff. of water and the mean molal activity coeff. of the ions in binary as well as ternary solns. Using the method developed by Patil and Dagade reported earlier in this journal and the McMillan-Meyer pair and triplet Gibbs energy interaction parameters, the thermodn. equil. const. (K) for the 18-crown-6:NH4+ complexes were detd. It is obsd. that the nature and polarizability of anions play important roles in imparting stability to the complexed species. The log10 K values for the 18-crown-6:NH4+ complexed species are lower than for the complexes involving alkali metal ions such as K+. The vol. of complexation for the studied systems obtained from the apparent molar volumes of ammonium halides in ternary solns. are pos. and of smaller magnitude than those reported for complexation with alkali ions. The results are further discussed in terms of water structural effects, complex formation, the role of counter anions and hydrophobic interactions.
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    70. 70
      Moberg, R.; Boekman, F.; Bohman, O.; Siegbahn, H. O. G. ESCA studies of phase-transfer catalysts in solution: ion pairing and surface activity. J. Am. Chem. Soc. 1991, 113 (10), 3663– 3667,  DOI: 10.1021/ja00010a005
      71
      ESCA studies of phase-transfer catalysts in solution: ion pairing and surface activity
      Moberg, R.; Boekman, F.; Bohman, O.; Siegbahn, H. O. G.
      Journal of the American Chemical Society (1991), 113 (10), 3663-7CODEN: JACSAT; ISSN:0002-7863.
      Phase-transfer catalysts in soln. have been studied by means of electron spectroscopy. Different anion-cation distributions at the surface were found depending on the anion identity. Thus, tetrabutylammonium perchlorate and tributyl-3-iodopropylammonium iodide show strong evidence of the formation of contact ion pairs at the surface. Conversely, the tetrabutylammonium nitrate and chloride show a more diffuse character of the anion distribution with respect to the surface. The obsd. differences in surface structure between the salts correlate with the variation in transfer coeffs. from aq. to org. phase.
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    71. 71
      Mbuna, J.; Takayanagi, T.; Oshima, M.; Motomizu, S. Evaluation of weak ion association between tetraalkylammonium ions and inorganic anions in aqueous solutions by capillary zone electrophoresis. J. Chromatogr. A 2004, 1022 (1), 191– 200,  DOI: 10.1016/j.chroma.2003.09.051
      72
      Evaluation of weak ion association between tetraalkylammonium ions and inorganic anions in aqueous solutions by capillary zone electrophoresis
      Mbuna, Julius; Takayanagi, Toshio; Oshima, Mitsuko; Motomizu, Shoji
      Journal of Chromatography A (2004), 1022 (1-2), 191-200CODEN: JCRAEY; ISSN:0021-9673. (Elsevier Science B.V.)
      The evaluation of weak ion assocn. between eleven (11) inorg. anions (charge -1 to -3) and five n-tetraalkylammonium ions, R4N+ (R: Me, Et, Pr, Bu, Am) in aq. media at 25 °C was studied. The anal. of ion assocn. equil. was carried out under acidic condition (formate buffer, pH 3.5) at low sepg. potential (-10 kV) using a coated capillary with suppressed electroosmotic flow (μ=4×10-5 cm2 V-1 s-1). Direct UV detection was done at anode (λ = 220 nm). The combination of the aforementioned conditions ensured that ion assocn. consts., Kass, between n-tetraalkylammonium ion and the small inorg. anions were reliably detd. after a non-linear least squares (NLLS) treatment of the measured anion's mobility. Like their larger counterparts, small anions showed increased interaction with an increase in size of pairing ions. Moreover, for a specific cation, the interaction of small anions increased with an increase in size of the hydrated anions as reflected by the relationship between the Kass and the Stokes' radius. A favorable comparison exists between the results presented in this work and those previously documented from other anal. techniques like conductometry. Qual., the mobility of the anions appeared to obey the Huckel's model more closely than the more elaborate Zwanzig and Hubbard-Onsager models.
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    72. 72
      Rouvière, A.; Ammann, M. The effect of fatty acid surfactants on the uptake of ozone to aqueous halogenide particles. Atmos. Chem. Phys. 2010, 10 (23), 11489– 11500,  DOI: 10.5194/acp-10-11489-2010
      73
      The effect of fatty acid surfactants on the uptake of ozone to aqueous halogenide particles
      Rouviere, A.; Ammann, M.
      Atmospheric Chemistry and Physics (2010), 10 (23), 11489-11500CODEN: ACPTCE; ISSN:1680-7316. (Copernicus Publications)
      The reactive uptake of ozone to deliquesced potassium iodide aerosol particles coated with linear satd. fatty acids (C9, C12, C15, C18 and C20) was studied. The expts. were performed in an aerosol flow tube at 293 K and atm. pressure. The uptake coeff. on pure deliquesced KI aerosol was γ = (1.10 ± 0.20) × 10-2 at 72-75% relative humidity. In presence of org. coatings, the uptake coeff. decreased significantly for long straight chain surfactants (≥C15), while it was only slightly reduced for the short ones (C9, C12). We linked the kinetic results to the monolayer properties of the surfactants, and specifically to the expected phase state of the monolayer formed (liq. expanded or liq. condensed state). The results showed a decrease of the uptake coeff. by 30% for C12, 85% for C15 and 50% for C18 in presence of a monolayer of a fatty acid at the equil. spreading pressure at the air/water interface. The variation among C12, C15 and C18 follows the d. of the monolayer at equil. spreading pressure, which is highest for the C15 fatty acid. We also investigated the effect of org. films to mixed deliquesced aerosol composed of a variable mixt. of KI and NaCl, which allowed detg. the resistance exerted to O3 at the aq. surface by the two longer chained surfactants pentadecanoic acid (C15) and stearic acid (C18). For these, the probability that a mol. hitting the surface is actually transferred to the aq. phase underneath was βC15 = 6.8 × 10-4 and βC18 = 3.3 × 10-4, resp. Finally, the effect of two-component coatings, consisting of a mixt. of long and short chained surfactants, was studied qual.
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    73. 73
      van Pinxteren, M.; Müller, C.; Iinuma, Y.; Stolle, C.; Herrmann, H. Chemical Characterization of Dissolved Organic Compounds from Coastal Sea Surface Microlayers (Baltic Sea, Germany). Environ. Sci. Technol. 2012, 46 (19), 10455– 10462,  DOI: 10.1021/es204492b
      74
      Chemical Characterization of Dissolved Organic Compounds from Coastal Sea Surface Microlayers (Baltic Sea, Germany)
      van Pinxteren, Manuela; Mueller, Conny; Iinuma, Yoshiteru; Stolle, Christian; Herrmann, Hartmut
      Environmental Science & Technology (2012), 46 (19), 10455-10462CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
      The physicochem. properties of the sea surface microlayer (SML), i.e. the boundary layer between the air and the sea, and its impact on air-sea exchange processes have been studied for decades. However, a detailed description about these processes remains incomplete. In order to obtain a better chem. characterization of the SML, in a case study 3 pairs of SML and corresponding bulk water samples were taken from the southern Baltic Sea. The samples were analyzed for dissolved org. C and dissolved total N, as well as for several org. N-contg. compds. and carbohydrates, namely aliph. amines, dissolved free amino acids, dissolved free monosaccharides, sugar alcs., and monosaccharide anhydrates. Therefore, reasonable anal. procedures with respect to desalting and enrichment were established. All aliph. amines and the majority of the studied amino acids (11 out of 18) were in the samples with av. concns. 53-1574 ng/L. The concns. of carbohydrates were slightly higher, av. 2900 ng/L. Calcn. of the enrichment factor (EF) between the sea surface microlayer and the bulk water showed that dissolved total N was more enriched (EF: 1.1 and 1.2) in the SML than dissolved org. C (EF: 1.0 and 1.1). The N-contg. orgs. were generally enriched in the SML (EF: 1.9-9.2), whereas dissolved carbohydrates were not enriched or even depleted (EF: 0.7-1.2). Although the studied compds. contributed on av. only 0.3% to the dissolved org. C and 0.4% to the total dissolved N fraction, these results underline the importance of single compd. anal. to det. SML structure, function, and its potential for a transfer of compds. into the atm.
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  • Supporting Information

    Supporting Information

    The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acsearthspacechem.1c00233.

    • Figures of valence spectra, O 1s and Br 3d photoelectron spectra, O 1s and C 1s photoemission spectra, ratio of C1s photoemission intensity of aliphatic carbon to that of amine coupled carbon, measured surface tension, and surface excess of TBA-Br, discussions of calculation of photoemission signal intensity ratios based on the attenuation model, surface excess of TBA-Br derived from surface tension measurements, and calculation of the uptake coefficient (PDF)


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