Electronic State Spectroscopy of Nitromethane and Nitroethane

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1. 1

   Walker, I. C.; Fluendy, M. A. D. Spectroscopy and Dynamics of Nitromethane (CH3NO2) and Its Anionic States. Int. J. Mass Spectrom. 2001, 205, 171– 182,  DOI: 10.1016/S1387-3806(00)00319-5

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   Spectroscopy and dynamics of nitromethane (CH3NO2) and its anionic states

   Walker, I. C.; Fluendy, M. A. D.

   International Journal of Mass Spectrometry (2001), 205 (1-3), 171-182CODEN: IMSPF8; ISSN:1387-3806. (Elsevier Science B.V.)

   Dissociative electron attachment in nitromethane has been investigated along with related spectroscopic measurements made using optical and electron scattering methods. The nature and dissocn. dynamics of the low-lying anionic states of nitromethane are discussed in the light of these expts. and the results of ab initio MO computations.
2. 2

   Lord-Garcia, J. Nitromethane. In Encyclopedia of Toxicology, 3rd ed.; Academic Press, 2014; pp 573– 574.

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   Shastri, A.; Das, A. K.; Sunanda, K.; Rajasekhar, B. N. Electronic States of Nitromethane: Experimental and Theoretical Studies. J. Quant. Spectrosc. Radiat. Transf. 2021, 276, 107933  DOI: 10.1016/j.jqsrt.2021.107933

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   Electronic states of nitromethane: Experimental and theoretical studies

   Shastri, Aparna; Das, Asim Kumar; Sunanda, K.; Rajasekhar, B. N.

   Journal of Quantitative Spectroscopy & Radiative Transfer (2021), 276 (), 107933CODEN: JQSRAE; ISSN:0022-4073. (Elsevier Ltd.)

   A comprehensive spectroscopic study of the UV-VUV photoabsorption spectrum of nitromethane in the energy region 5.4-11.8 eV (43,500-95,000 cm-1) using synchrotron radiation is presented; the VUV absorption spectrum in the region > 9 eV being reported for the first time. The obsd. spectral features are assigned to various valence and Rydberg transitions, supported by quantum chem. calcns. using the TDDFT method. The 6 eV region is dominated by a broad, intense absorption band peaking at ∼ 6.2 eV assigned to the π-π* valence transition, followed by rich Rydberg series converging to the first four ionization potentials of nitromethane. Theor. calcns. of orbital energies as well as Rydberg series anal. indicate that the third IP is located at 11.95 eV, in contrast to the earlier estd. value of 11.5 eV. Series of bands attributed to vibrational transitions accompanying the 3s (6a''), 3p(6a"), 3s(10a') and 3s(5a'') Rydberg transitions are obsd. in the 60,000-73,000 cm-1 region and are tentatively assigned to progressions involving the NO2 in-plane rock and CH3 asym. deform modes. The liq. phase IR spectrum is revisited and assigned with the help of DFT calcns. A few new bands are obsd. and assigned to overtone and combination modes. Theor. simulated potential energy curves of the first few excited singlet and triplet states with respect to the CN and NO bond lengths are useful in explaining some of the incompletely understood features of the photodissocn. dynamics of nitromethane. It is found that direct dissocn. in the Franck Condon region is a possible mechanism for the CH3NO + O channel, while singlet-triplet crossings play an important role in CN and NO bond scissions.
4. 4

   McAllister, T. Electron Impact Excitation Spectra in an Ion Cyclotron Resonance Mass Spectrometer. J. Chem. Phys. 1972, 57, 3353– 3355,  DOI: 10.1063/1.1678766

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   Electron impact excitation spectra in an ion cyclotron resonance mass spectrometer

   McAllister, T.

   Journal of Chemical Physics (1972), 57 (8), 3353-5CODEN: JCPSA6; ISSN:0021-9606.

   Electron-impact excitation spectra were obtained from an ion cyclotron resonance (ICR) mass spectrometer by monitoring the current of scattered electrons transmitted along the ICR cell. The CCl4 and SF6 scavenger techniques were also used to verify specific features of these spectra. The spectrum of N2 is strongly influenced by the depth of potential well employed and the SF6 technique gives an identical spectrum to that of the cattered current monitor at higher well depths, indicating that the narrow energy width of the SF6 resonance capture peak does not influence the spectrum obtained in the ICR. Spectra of PhNO2 and MeNO2 showed peaks which could be attributed to the NO2 group. NO2- ions interfered with the PhNO2 spectrum but not the MeNO2 spectrum.
5. 5

   Goebbert, D. J.; Pichugin, K.; Sanov, A. Low-Lying Electronic States of CH3NO2 via Photoelectron Imaging of the Nitromethane Anion. J. Chem. Phys. 2009, 131, 164308  DOI: 10.1063/1.3256233

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   Low-lying electronic states of CH3NO2 via photoelectron imaging of the nitromethane anion

   Goebbert, Daniel J.; Pichugin, Kostyantyn; Sanov, Andrei

   Journal of Chemical Physics (2009), 131 (16), 164308/1-164308/7CODEN: JCPSA6; ISSN:0021-9606. (American Institute of Physics)

   Neg.-ion photoelectron imaging at 532, 392, 355, and 266 nm was used to assign several low-lying electronic states of neutral nitromethane CH3NO2 at the geometry corresponding to the anion equil. The obsd. neutral states include (in the order of increasing binding energy) the X 1A' ground state, two triplet excited states, a 3A'' and b 3A'', and the 1st excited singlet state, A 1A''. The state assignments are aided by the anal. of the photoelectron angular distributions resulting from electron detachment from the a' and a'' symmetry MOs and the results of theor. calcns. The singlet-triplet (X 1A'-a 3A'') splitting in nitromethane is detd. as 2.90+0.02/-0.07 eV, while the vibrational structure of the band corresponding to the formation of the a 3A'' state of CH3NO2 is attributed to the ONO bending and NO2 wagging motions excited in the photodetachment of the anion. (c) 2009 American Institute of Physics.
6. 6

   Flicker, W. M.; Mosher, O. A.; Kuppermann, A. Variable Angle Electron-Impact Excitation of Nitromethane. J. Chem. Phys. 1980, 72, 2788– 2794,  DOI: 10.1063/1.439427

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   Variable angle electron impact excitation of nitromethane

   Flicker, Wayne M.; Mosher, Oren A.; Kuppermann, Aron

   Journal of Chemical Physics (1980), 72 (4), 2788-94CODEN: JCPSA6; ISSN:0021-9606.

   The electron-impact excitation of nitromethane was studied at incident electron energies of 25, 55, and 90 eV, at scattering angles from 6° to 80°. The lowest-lying inelastic process which is obsd. is a previously unreported feature with a max. intensity at 3.8 eV energy loss. This feature represents at least 1 singlet→triplet transition. It is likely that this 3.8 eV triplet feature plays a central role in the gas phase photolysis of nitromethane. A weak inelastic process with a peak at 4.45 eV was also obsd., along with a strong transition at 6.23 eV. Both of these excitations are well known from optical spectra, and they are generally believed to represent spin-allowed n → π* and π → π* transitions, resp. Their assignments are discussed in detail. In addn., 7 other transitions, several of which have not been reported previously, were detected in the 7-12 eV energy-loss range. Three of these transitions, at 8.3, 8.85, and 11.73 eV energy loss, are tentatively assigned to Rydberg excitations of increasingly tightly bound electrons into a 3s Rydberg orbital.
7. 7

   Linnett, J. W.; Avery, W. H. Infra-Red and Raman Spectra of Polyatomic Molecules. IV. Allene. J. Chem. Phys. 1938, 6, 686– 691,  DOI: 10.1063/1.1750152

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   Infrared and Raman spectra of polyatomic molecules. IV. Allene

   Linnett, J. W.; Avery, W. H.

   Journal of Chemical Physics (1938), 6 (), 686-91CODEN: JCPSA6; ISSN:0021-9606.

   The infrared absorption spectrum of H2C: C: CH2 contains bands at 4200, 2960, 2420, 1980, 1700, 1389, 1165, 1031 and 852 cm.-1; the Raman spectrum contains shifts of 3062, 2992, 2858, 1956, 1684, 1430, 1069, 838, 705 and 353 cm.-1. With the aid of heat-capacity data values were assigned to the frequencies of all the 11 fundamental modes of vibration of H2C:C:CH2; the assignment accounted for all the features of the Raman and infrared spectra. The free energy, entropy and heat capacity were calcd.; expressions were derived for the first 2 as functions of temp.
8. 8

   Smith, D. C.; Pan, C. Y.; Nielsen, J. R. Vibrational Spectra of the Four Lowest Nitroparaffins. J. Chem. Phys. 1950, 18, 706– 712,  DOI: 10.1063/1.1747732

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   Vibrational spectra of the four lowest nitroparaffins

   Smith, Don C.; Pan, Chi-Yuan; Nielsen, J. Rud

   Journal of Chemical Physics (1950), 18 (), 706-12CODEN: JCPSA6; ISSN:0021-9606.

   The infrared spectra from 2 to 22 μ of nitromethane, nitroethane, 1-nitropropane, and 2-nitropropane have been obtained for both vapor and liquid phases. The Raman shifts have been measured for the liquids, and for nitromethane the polarizations of the bands have been detd. A satisfactory interpretation of the spectra has been obtained for nitromethane on the basis of assigned fundamental frequencies that agree with those proposed previously by Wells and Wilson (C.A. 35, 3524.8), except for the B1 methyl rocking mode. The fundamental frequencies have not been detd. for the other compds., but the positions of the nitro-group absorptions have been detd. empirically.
9. 9

   Jones, W. J.; Sheppard, N. The Gas-Phase Infrared Spectra of Nitromethane and Methyl Boron Difluoride; Fine Structure Caused by Internal Rotation. Proc. R. Soc. London, Ser. A 1968, 304, 135– 155,  DOI: 10.1098/rspa.1968.0078

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    Courtecuisse, S.; Cansell, F.; Fabre, D.; Petitet, J. P. Comparative Raman Spectroscopy of Nitromethane-H3, Nitromethane-D3, and Nitroethane up to 20 GPa. J. Chem. Phys. 1998, 108, 7350– 7355,  DOI: 10.1063/1.476154

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    Comparative Raman spectroscopy of nitromethane-h3, nitromethane-d3, and nitroethane up to 20 GPa

    Courtecuisse, Stephane; Cansell, Francois; Fabre, Denise; Petitet, Jean Pierre

    Journal of Chemical Physics (1998), 108 (17), 7350-7355CODEN: JCPSA6; ISSN:0021-9606. (American Institute of Physics)

    MeNO2 was studied as a model of energetic aliph. nitro compds. Initiation of the MeNO2 decompn. mechanism in the vicinity of its explosive-decompn. pressure conditions was studied under high static pressure at ambient temp. by Raman spectroscopy. The vibrational modes νa(NO2) and, to a lesser degree, νs(NO2) show a specific behavior at the solid (II)-solid (III) 7.5 GPa transition (at ambient temp.). A comparison of the Raman spectrum of MeNO2 with new, high-pressure Raman-spectroscopic results for CD3NO2 and EtNO2 allows characterization of the physicochem. behavior of these 3 compds. in relation to their detonic properties.
11. 11

    Kobayashi, T.; Nagakura, S. Photoelectron Spectra of Nitro-Compounds. Chem. Lett. 1972, 1, 903– 907,  DOI: 10.1246/cl.1972.903

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    Rabalais, J. W. Photoelectron Spectroscopic Investigation of the Electronic Structure of Nitromethane and Nitrobenzene. J. Chem. Phys. 1972, 57, 960– 967,  DOI: 10.1063/1.1678346

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    Photoelectron spectroscopic investigation of the electronic structure of nitromethane and nitrobenzene

    Rabalais, J. W.

    Journal of Chemical Physics (1972), 57 (2), 960-7CODEN: JCPSA6; ISSN:0021-9606.

    The electronic structure of MeNO2 and PhNO2 was studied by high-resolution He I photoelectron spectroscopy and quantum chem. calcns. of the intermediate neglect of differential overlap type. The spectra of MeNO2 and CD3NO2 exhibit 6 ionization bands below 21 eV. The transitions to the ground and 1st excited ionic states have extensive vibrational structure which was identified as the symmetric NO2 bending mode. The spectra of PhNO2 and C6D5NO2 contain at least 10 ionization bands at <21 eV with resolved vibrational structure only in the transition to the ground ionic state. The most loosely-bound MO of MeNO2 was identified as the 5a1 NO2-σ bonding orbital, and that of PhNO2 as the b1 ring-π orbital. The nonbonding a2π orbital was assigned to the 2nd and 4th ionization bands in these resp. mols. By using the MO ordering found here, the 198 nm absorption band of MeNO2 was assigned to the π*(2b1) ← σ(5a1) transition and the long wavelength bands of PhNO2 are assigned to π* ← π transitions, one of which involves intramol. charge transfer from the Ph ring to the NO2 moiety.
13. 13

    Rao, C. N. R. Photoelectron Spectra of C-Nitro & N-Nitro Compounds. Indian J. Chem. 1976, 14, 147– 149

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    Photoelectron spectra of C-nitro and N-nitro compounds

    Rao, C. N. R.

    Indian Journal of Chemistry, Section A: Inorganic, Physical, Theoretical & Analytical (1976), 14A (3), 147-9CODEN: IJCADU; ISSN:0376-4710.

    Photoelectron spectra of aliph. nitro compds., e.g., MeNO2, Cl3CNO2, have been studied and assignments made on the basis of MO calcns. and electronic absorption spectra. Substituent effects due to the nitro group are discussed. Photoelectron spectra of Me2NNO2 and Me2NNO and compared.
14. 14

    Mok, C. Y.; Chin, W. S.; Huang, H. H. He (I) and He (II) Photoelectron Spectra of Simple Nitroalkanes. J. Electron Spectrosc. Relat. Phenom. 1991, 57, 213– 222,  DOI: 10.1016/0368-2048(91)85025-O

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    Helium(II) and He(II) photoelectron spectra of simple nitroalkanes

    Mok, C. Y.; Chin, W. S.; Huang, H. H.

    Journal of Electron Spectroscopy and Related Phenomena (1991), 57 (2), 213-22CODEN: JESRAW; ISSN:0368-2048.

    He(II) photoelectron spectra of nitromethane, nitroethane, 1- and 2-nitropropane were recorded and compared with the corresponding He(I) spectra. The relative Hg(I)/He(II) spectral band intensities provide clear evidence of ascribing the first two max. in the range 10-12 eV to ionization processes involving the removal of electrons from the orbitals n0+, n0-, and π2. Similarly the band at ≈17 eV is attributed to ejection of electrons from the π1 and σNO- orbitals. Detailed assignment of spectral bands is made on the basis of bandshape and intensity, as well as ab initio SCF MO calcns. using the 6-31 G basis set. In the He(II) spectra, two bands in the region 18-22 eV are assigned to σNO+ and an orbital with 2sN and 2sO character.
15. 15

    Nelson, T.; Bjorgaard, J.; Greenfield, M.; Bolme, C.; Brown, K.; McGrane, S.; Scharff, R. J.; Tretiak, S. Ultrafast Photodissociation Dynamics of Nitromethane. J. Phys. Chem. A 2016, 120, 519– 526,  DOI: 10.1021/acs.jpca.5b09776

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    Ultrafast Photodissociation Dynamics of Nitromethane

    Nelson, Tammie; Bjorgaard, Josiah; Greenfield, Margo; Bolme, Cindy; Brown, Katie; McGrane, Shawn; Scharff, R. Jason; Tretiak, Sergei

    Journal of Physical Chemistry A (2016), 120 (4), 519-526CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)

    Nitromethane (NM), a high explosive (HE) with low sensitivity, is known to undergo photolysis upon UV irradn. The optical transparency, homogeneity, and extensive study of NM make it an ideal system for studying photodissocn. mechanisms in conventional HE materials. The photochem. processes involved in the decompn. of NM could be applied to the future design of controllable photoactive HE materials. In this study, the photodecompn. of NM from the nπ* state excited at 266 nm is being investigated on the femtosecond time scale. UV femtosecond transient absorption (TA) spectroscopy and excited state femtosecond stimulated Raman spectroscopy (FSRS) are combined with nonadiabatic excited state mol. dynamics (NA-ESMD) simulations to provide a unified picture of NM photodecompn. The FSRS spectrum of the photoproduct exhibits peaks in the NO2 region and slightly shifted C-N vibrational peaks pointing to Me nitrite formation as the dominant photoproduct. A total photolysis quantum yield of 0.27 and an nπ* state lifetime of ∼20 fs were predicted from NA-ESMD simulations. Predicted time scales revealed that NO2 dissocn. occurs in 81 ± 4 fs and Me nitrite formation is much slower having a time scale of 452 ± 9 fs corresponding to the excited state absorption feature with a decay of 480 ± 17 fs obsd. in the TA spectrum. Although simulations predict C-N bond cleavage as the primary photochem. process, the relative time scales are consistent with isomerization occurring via NO2 dissocn. and subsequent rebinding of the Me radical and nitrogen dioxide.
16. 16

    Rodríguez, J. D.; González, M. G.; Rubio-Lago, L.; Bañares, L.; Samartzis, P. C.; Kitsopoulos, T. N. Stereodynamics of the Photodissociation of Nitromethane at 193 Nm: Unravelling the Dissociation Mechanism. J. Phys. Chem. A 2013, 117, 8175– 8183,  DOI: 10.1021/jp403272x

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    Stereodynamics of the Photodissociation of Nitromethane at 193 nm: Unravelling the Dissociation Mechanism

    Rodriguez, J. D.; Gonzalez, M. G.; Rubio-Lago, L.; Banares, L.; Samartzis, P. C.; Kitsopoulos, T. N.

    Journal of Physical Chemistry A (2013), 117 (34), 8175-8183CODEN: JPCAFH; ISSN:1089-5639. (American Chemical Society)

    The photodissocn. of nitromethane at 193 nm is reviewed in terms of new stereodynamical information provided by the measurement of the first four Dixon's bipolar moments, β02(20), β00(22), β02(02), and β02(22), using slice imaging. The measured speed-dependent β02(20) (directly related with the spatial anisotropy parameter β) indicates that after one-photon absorption to the S3(21A'') state by an allowed perpendicular transition, two reaction pathways can compete with similar probability, a direct dissocn. process yielding ground-state CH3 and NO2(12A2) radicals and a indirect dissocn. through conical intersections in which NO2 radicals are formed in lower-lying electronic states. A particularly important result from our measurements is that the low recoil energy part of the Me fragment translational energy distribution presents a contribution with parallel character, irresp. of the exptl. conditions employed, that the authors attribute to parent cluster dissocn. Moreover, the pos. values found for the β00(22) bipolar moment indicates some propensity for the fragment's recoil velocity and angular momentum vectors to be parallel.
17. 17

    Campbell, I. M.; Goodman, K. Rate Constants for Reactions of Hydroxyl Radicals with Nitromethane and Methyl Nitrite Vapours at 292 K. Chem. Phys. Lett. 1975, 36, 382– 384,  DOI: 10.1016/0009-2614(75)80262-4

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    Rate constants for reactions of hydroxyl radicals with nitromethane and methyl nitrite vapors at 292.deg.K

    Campbell, I. M.; Goodman, K.

    Chemical Physics Letters (1975), 36 (3), 382-4CODEN: CHPLBC; ISSN:0009-2614.

    The variations of yields of CO2 from the gase phase H2O2 + NO2 + CO chain reaction system with added nitromethane of methyl nitrite have given consts. for reactions of OH radicals with these substrates. At 292° K these are (5.5 ± 0.6) × 108 and (8.0 ± 1.1) × 108 dm3 mole-1 sec-1 resp.
18. 18

    Liu, R.; Huie, R. E.; Kurylo, M. J.; Nielsen, O. J. The Gas Phase Reactions of Hydroxyl Radicals with a Series of Nitroalkanes over the Temperature Range 240-400 K. Chem. Phys. Lett. 1990, 167, 519– 523,  DOI: 10.1016/0009-2614(90)85462-L

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    The gas phase reactions of hydroxyl radicals with a series of nitroalkanes over the temperature range 240-400 K

    Liu, Renzhang; Huie, Robert E.; Kurylo, Michael J.; Nielsen, Ole J.

    Chemical Physics Letters (1990), 167 (6), 519-23CODEN: CHPLBC; ISSN:0009-2614.

    Abs. rate consts. were detd. for the gas phase reactions of OH radicals with a series of nitroalkanes by the flash photolysis-resonance fluorescence technique. Expts. were performed at total pressures from 25 to 50 Torr using Ar as a diluent gas. Expts. with nitromethane and nitromethane-d3 at 296 K yielded rate consts. of (1.58 ± 0.09) × 10-14 and (0.9 ± 0.04) × 10-14 cm3 mol.-1 s-1, resp. Data from expts. at 240-400 K for nitroethane, 1-nitropropane, 1-nitrobutane, and 1-nitropentane were used to evaluate Arrhenius parameters. The results are discussed in terms of the reaction mechanism, and are compared to previous literature data.
19. 19

    Murrell, J. N.; Vidal, B.; Guest, M. F. Structure and Electronic Properties of the Nitromethyl Anion, Nitromethane and Aci-Nitromethane. J. Chem. Soc., Faraday Trans. 2 1975, 71, 1577– 1582,  DOI: 10.1039/f29757101577

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    Structure and electronic properties of the nitromethyl anion, nitromethane, and aci-nitromethane

    Murrell, John N.; Vidal, Bernard; Guest, Martyn F.

    Journal of the Chemical Society, Faraday Transactions 2: Molecular and Chemical Physics (1975), 71 (9), 1577-82CODEN: JCFTBS; ISSN:0300-9238.

    Ab initio SCF MO calcns. for CH2NO2- using minimal and double-zeta basis sets showed that the planar configuration was most favored. Potential energy contours suggested that the planar form would protonate at O and the pyramidal form at C, in accord with expt. Calcns. with the minimal basis showed that MeNO2 was more stable than the aci forms but using the double-zeta basis cis-aci-MeNO2 was slightly more stable than MeNO2, due to an artefact of the basis. The photoelectron spectrum of MeNO2 was reassigned on the basis of ionizaton potential calcns.
20. 20

    Lopes, A. R.; Sanchez, S. d’A.; Bettega, M. H. F. Elastic Scattering of Low-Energy Electrons by Nitromethane. Phys. Rev. A 2011, 83, 062713  DOI: 10.1103/PhysRevA.83.062713

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    Elastic scattering of low-energy electrons by nitromethane

    Lopes, A. R.; Sanchez, S. d'A.; Bettega, M. H. F.

    Physical Review A: Atomic, Molecular, and Optical Physics (2011), 83 (6, Pt. A), 062713/1-062713/6CODEN: PLRAAN; ISSN:1050-2947. (American Physical Society)

    In this work, we present integral, differential, and momentum transfer cross sections for elastic scattering of low-energy electrons by nitromethane, for energies up to 10 eV. We calcd. the cross sections using the Schwinger multichannel method with pseudopotentials, in the static-exchange and in the static-exchange plus polarization approxns. The computed integral cross sections show a π* shape resonance at 0.70 eV in the static-exchange-polarization approxn., which is in reasonable agreement with exptl. data. We also found a σ* shape resonance at 4.8 eV in the static-exchange-polarization approxn., which has not been previously characterized by the expt. We also discuss how these resonances may play a role in the dissocn. process of this mol.
21. 21

    Antunes, R.; Almeida, D.; Martins, G.; Mason, N. J.; Garcia, G.; Maneira, M. J. P.; Nunes, Y.; Limão-Vieira, P. Negative Ion Formation in Potassium–Nitromethane Collisions. Phys. Chem. Chem. Phys. 2010, 12, 12513– 12519,  DOI: 10.1039/c004467a

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    Negative ion formation in potassium-nitromethane collisions

    Antunes, R.; Almeida, D.; Martins, G.; Mason, N. J.; Garcia, G.; Maneira, M. J. P.; Nunes, Y.; Limao-Vieira, P.

    Physical Chemistry Chemical Physics (2010), 12 (39), 12513-12519CODEN: PPCPFQ; ISSN:1463-9076. (Royal Society of Chemistry)

    Ion-pair formation in gaseous nitromethane (CH3NO2) induced by electron transfer has been studied by investigating the products of collisions between fast potassium atoms and nitromethane mols. using a crossed mol.-beam technique. The neg. ions formed in such collisions were analyzed using time-of-flight mass spectroscopy. The six most dominant product anions are NO2-, O-, CH3NO2-, OH-, CH2NO2- and CNO-. By using nitromethane-d3 (CD3NO2), we found that previous mass 17 amu assignment to O- delayed fragment, is in the present expt. may be unambiguously assigned to OH-. The formation of CH2NO2- may be explained in terms of dissociative electron attachment to highly vibrationally excited mols.
22. 22

    Alizadeh, E.; Ferreira da Silva, F.; Zappa, F.; Mauracher, A.; Probst, M.; Denifl, S.; Bacher, A.; Märk, T. D.; Limão-Vieira, P.; Scheier, P. Dissociative Electron Attachment to Nitromethane. Int. J. Mass Spectrom. 2008, 271, 15– 21,  DOI: 10.1016/j.ijms.2007.11.004

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    Dissociative electron attachment to nitromethane

    Alizadeh, E.; Ferreira da Silva, F.; Zappa, F.; Mauracher, A.; Probst, M.; Denifl, S.; Bacher, A.; Maerk, T. D.; Limao-Vieira, P.; Scheier, P.

    International Journal of Mass Spectrometry (2008), 271 (1-3), 15-21CODEN: IMSPF8; ISSN:1387-3806. (Elsevier B.V.)

    Dissociative electron attachment (DEA) measurements to nitromethane, CH3NO2, in the gas phase have been revisited by making use of a high mass-resoln. sector field instrument. Anion efficiency curves for 16 neg. charged fragments have been measured in the electron energy region from about 0 to 16 eV with an energy resoln. of ∼1 eV. Eight new anions have been detected, CH2NO2-, CHNO2-, CH2NO-, H2NO-, CH3-, CH2-, CH- and H-. The five most dominant product anions are NO2-, O-, OH-, CN- and CNO-, all of them featuring two high-energy resonances at about 5 eV and 10 eV. Formation of CH2NO2- at low electron energies has been explained in terms of DEA to highly vibrationally excited mols. The std. enthalpy of formation of CH2NO2- and H-, CH2- and NO- radicals have been estd. as Δf H g°(CH2NO2-) = -1.71 eV, Δf H g°(H-) = 2.09 eV, Δf H g°(CH2-) = 3.5 eV and Δf H g°(NO-) = -1.93 eV, resp.
23. 23

    Shafiee, A.; Khoobi, M. Nitroethane. In Encyclopedia of Toxicology, 3rd ed.; Academic Press, 2014; pp 543– 547.

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    Goodeve, J. W. The Absorption Spectra of Ethyl Nitrate, Ethyl Nitrite, and Nitroethane. Trans. Faraday Soc. 1934, 30, 504– 508,  DOI: 10.1039/tf9343000504

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    Absorption spectra of ethyl nitrate, ethyl nitrite and nitroethane

    Goodeve, Janet W.

    Transactions of the Faraday Society (1934), 30 (), 504-8CODEN: TFSOA4; ISSN:0014-7672.

    Ultra-violet absorption spectra were photographed for the vapors of EtNO3, EtONO and EtNO2 and extinction coeffs. were detd. Each of these spectra is continuous and consists of 2 broad overlapping bands. The extinction coeff. curve of Et nitrate is similar to that of nitroethane but is different from that of Et nitrite. The absorbing group is considered to be the N-O combination.
25. 25

    Palmer, M. H.; Ridley, T.; Hoffmann, S. V.; Jones, N. C.; Coreno, M.; De Simone, M.; Grazioli, C.; Biczysko, M.; Baiardi, A.; Limão-Vieira, P. Interpretation of the Vacuum Ultraviolet Photoabsorption Spectrum of Iodobenzene by Ab Initio Computations. J. Chem. Phys. 2015, 142, 134302  DOI: 10.1063/1.4916121

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    Interpretation of the vacuum ultraviolet photoabsorption spectrum of iodobenzene by ab initio computations

    Palmer, Michael H.; Ridley, Trevor; Hoffmann, Soeren Vroenning; Jones, Nykola C.; Coreno, Marcello; de Simone, Monica; Grazioli, Cesare; Biczysko, Malgorzata; Baiardi, Alberto; Limao-Vieira, Paulo

    Journal of Chemical Physics (2015), 142 (13), 134302/1-134302/13CODEN: JCPSA6; ISSN:0021-9606. (American Institute of Physics)

    Identification of many Rydberg states in iodobenzene, esp. from the 1st and 4th ionization energies (IE1 and IE4, X2B1 and C2B1), has become possible using a new UV and vacuum-UV (VUV) absorption spectrum, in the region 29,000-87,000 cm-1 (3.60-10.79 eV), measured at room temp. with synchrotron radiation. A few Rydberg states based on IE2 (A2A2) were found, but those based on IE3 (B2B2) are undetectable. The almost complete absence of observable Rydberg states relating to IE2 and IE3 (A2A2 and B2B2, resp.) is attributed to them being coupled to the near-continuum, high-energy region of Rydberg series converging on IE1. Theor. studies of the UV and VUV spectra used both time-dependent d. functional (TDDFT) and multi-ref. multi-root doubles and singles-CI methods. The theor. adiabatic excitation energies, and their corresponding vibrational profiles, gave a satisfactory interpretation of the exptl. results. The calcns. indicate that the UV onset contains both 11B1 and 11B2 states with very low oscillator strength, while the 21B1 state was found to lie under the lowest ππ* 11A1 state. All 3 of these 1B1 and 1B2 states are excitations into low-lying σ* orbitals. The strongest VUV band near 7 eV contains 2 very strong ππ* valence states, together with other weak contributors. The lowest Rydberg 4b16s state (31B1) is very evident as a sharp multiplet near 6 eV; its position and vibrational structure are well reproduced by the TDDFT results. (c) 2015 American Institute of Physics.
26. 26

    Eden, S.; Limão-Vieira, P.; Hoffmann, S. V.; Mason, N. J. VUV Photoabsorption in CF3X (X = Cl, Br, I) Fluoro-Alkanes. Chem. Phys. 2006, 323, 313– 333,  DOI: 10.1016/j.chemphys.2005.09.040

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    VUV photoabsorption in CF3X (X=Cl, Br, I) fluoro-alkanes

    Eden, S.; Limao-Vieira, P.; Hoffmann, S. V.; Mason, N. J.

    Chemical Physics (2006), 323 (2-3), 313-333CODEN: CMPHC2; ISSN:0301-0104. (Elsevier B.V.)

    A new UV beam line has been constructed at the Institute of Storage Rings, University of Aarhus (ISA) to study the Photoabsorption of aeronomic mols. In this paper, visible-UV spectra of CF3Cl and CF3Br are reported at high-resoln. in the energy range 3.9-10.8 eV (320-115 nm). For both mols., the present work provides the most reliable abs. cross-sections available at energies above the lowest lying electronic transition, the dissociative A band. Results are compared with earlier data including the recently published photoabsorption spectrum of CF3I [N. J. Mason, P. Limao-Vieira, S. Eden, P. Kendall, S. Pathak, A. Dawes, J. Tennyson, P. Tegeder, M. Kitajima, M. Okamoto, K. Sunohara, H. Tanaka, H. Cho, S. Samukawa, S. V. Hoffmann, D. Newnham, S. M. Spyrou, Int. J. Mass Spectrom. 223-224 (2003) 647]. The CF3I spectrum is revisited and new assignments made, including the extension of previously proposed ns Rydberg series. A detailed description of the ASTRID photoabsorption app. at ISA is provided for the first time.
27. 27

    Barca, G. M. J.; Bertoni, C.; Carrington, L.; Datta, D.; De Silva, N.; Deustua, J. E.; Fedorov, D. G.; Gour, J. R.; Gunina, A. O.; Guidez, E. Recent Developments in the General Atomic and Molecular Electronic Structure System. J. Chem. Phys. 2020, 152, 154102  DOI: 10.1063/5.0005188

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    Recent developments in the general atomic and molecular electronic structure system

    Barca, Giuseppe M. J.; Bertoni, Colleen; Carrington, Laura; Datta, Dipayan; De Silva, Nuwan; Deustua, J. Emiliano; Fedorov, Dmitri G.; Gour, Jeffrey R.; Gunina, Anastasia O.; Guidez, Emilie; Harville, Taylor; Irle, Stephan; Ivanic, Joe; Kowalski, Karol; Leang, Sarom S.; Li, Hui; Li, Wei; Lutz, Jesse J.; Magoulas, Ilias; Mato, Joani; Mironov, Vladimir; Nakata, Hiroya; Pham, Buu Q.; Piecuch, Piotr; Poole, David; Pruitt, Spencer R.; Rendell, Alistair P.; Roskop, Luke B.; Ruedenberg, Klaus; Sattasathuchana, Tosaporn; Schmidt, Michael W.; Shen, Jun; Slipchenko, Lyudmila; Sosonkina, Masha; Sundriyal, Vaibhav; Tiwari, Ananta; Galvez Vallejo, Jorge L.; Westheimer, Bryce; Wloch, Marta; Xu, Peng; Zahariev, Federico; Gordon, Mark S.

    Journal of Chemical Physics (2020), 152 (15), 154102CODEN: JCPSA6; ISSN:0021-9606. (American Institute of Physics)

    A discussion of many of the recently implemented features of GAMESS (General Atomic and Mol. Electronic Structure System) and LibCChem (the C + + CPU/GPU library assocd. with GAMESS) is presented. These features include fragmentation methods such as the fragment MO, effective fragment potential and effective fragment MO methods, hybrid MPI/OpenMP approaches to Hartree-Fock, and resoln. of the identity second order perturbation theory. Many new coupled cluster theory methods have been implemented in GAMESS, as have multiple levels of d. functional/tight binding theory. The role of accelerators, esp. graphical processing units, is discussed in the context of the new features of LibCChem, as it is the assocd. problem of power consumption as the power of computers increases dramatically. The process by which a complex program suite such as GAMESS is maintained and developed is considered. Future developments are briefly summarized. (c) 2020 American Institute of Physics.
28. 28

    Bauernschmitt, R.; Ahlrichs, R. Treatment of Electronic Excitations within the Adiabatic Approximation of Time Dependent Density Functional Theory. Chem. Phys. Lett. 1996, 256, 454– 464,  DOI: 10.1016/0009-2614(96)00440-X

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    Treatment of electronic excitations within the adiabatic approximation of time dependent density functional theory

    Bauernschmitt, Ruedger; Ahlrichs, Reinhart

    Chemical Physics Letters (1996), 256 (4,5), 454-464CODEN: CHPLBC; ISSN:0009-2614. (Elsevier)

    Time dependent d. functional methods are applied in the adiabatic approxn. to compute low-lying electronic excitations of N2, ethylene, formaldehyde, pyridine and porphin. Out of various local, gradient-cor. and hybrid (including exact exchange) functionals, the best results are obtained for the three-parameter Lee-Yang-Parr (B3LYP) functional proposed by Becke. B3LYP yields excitation energies about 0.4 eV too low but typically gives the correct ordering of states and constitutes a considerable improvement over HF-based approaches requiring comparable numerical work.
29. 29

    Casida, M. E. Time-Dependent Density-Functional Theory for Molecules and Molecular Solids. J. Mol. Struct.: THEOCHEM 2009, 914, 3– 18,  DOI: 10.1016/j.theochem.2009.08.018

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    Time-dependent density-functional theory for molecules and molecular solids

    Casida, Mark E.

    Journal of Molecular Structure: THEOCHEM (2009), 914 (1-3), 3-18CODEN: THEODJ; ISSN:0166-1280. (Elsevier B.V.)

    A review. Time-dependent d.-functional theory (TDDFT) has become a well-established part of the modern theor. chemist's toolbox for treating electronic excited states. Yet, though applications of TDDFT abound in quantum chem., review articles specifically focusing on TDDFT for chem. applications are relatively rare. This article helps to fill the void by first giving a historical review of TDDFT, with emphasis on mol. excitations and aspects of TDDFT which are important for quantum chem. applications, followed by a discussion of some modern evolutions with emphasis on the articles in this vol., and ending with a few thoughts about the future of TDDFT.
30. 30

    Tannenbaum, E.; Myers, R. J.; Gwinn, W. D. Microwave Spectra, Dipole Moment, and Barrier to Internal Rotation of CH3NO2 and CD3NO2. J. Chem. Phys. 1956, 25, 42– 47,  DOI: 10.1063/1.1742845

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    Microwave spectra, dipole moment, and barrier to internal rotation of CH3NO2 and CD3NO2

    Tannenbaum, Eileen; Myers, Rollie J.; Gwinn, Wm. D.

    Journal of Chemical Physics (1956), 25 (), 42-7CODEN: JCPSA6; ISSN:0021-9606.

    The J = 1 and J = 2 to J = 3 transitions for MeNO2 and CD3NO2 were assigned for several internal rotational states. The best values of the rotational consts. B and C were 10,542.7 and 5876.6 Mc./sec. for MeNO2 and 8697.1 and 5254.3 Mc./sec. for CD3NO2. The rotational const. for the NO2 group about the symmetry axis is 13,277.5 Mc./sec. These consts. are detd. by assuming no inertial defect; slightly different values are calcd. if other assumptions are made. Some of the assigned lines are a very sensitive function of the low barrier to internal rotation. The barrier term V6 was detd. to be 6.03 cal./mole for MeNO2 and 5.19 cal./mole for CD3NO2. The term V12 is less than 0.05 cal./mole. The dipole moment of MeNO2 is 3.46 debye units.
31. 31

    Tannenbaum, E.; Johnson, R. D.; Myers, R. J.; Gwinn, W. D. Microwave Spectrum and Barrier to Internal Rotation of Nitromethane. J. Chem. Phys. 1954, 22, 949,  DOI: 10.1063/1.1740230

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    Microwave spectrum and barrier to internal rotation of nitromethane

    Tannenbaum, Eileen; Johnson, Russell D.; Myers, Rollie J.; Gwinn, Wm. D.

    Journal of Chemical Physics (1954), 22 (), 949CODEN: JCPSA6; ISSN:0021-9606.

    Assignments were made for the J = 1 to J = 2 transitions of nitromethane. The barrier to internal rotation about the symmetry axis of the Me and NO2 groups was taken to have the form, V = V6(1 - cos 6φ). The value for the barrier which gave the best agreement between the calcd. and observed spectra was V6 = 6.00 ± 0.03 cal./mole.
32. 32

    McKee, M. L. Ab Initio and MNDO Study of Nitromethane and the Nitromethyl Radical. J. Am. Chem. Soc. 1985, 107, 1900– 1904,  DOI: 10.1021/ja00293a017

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    Ab initio and MNDO study of nitromethane and the nitromethyl radical

    McKee, Michael L.

    Journal of the American Chemical Society (1985), 107 (7), 1900-4CODEN: JACSAT; ISSN:0002-7863.

    Ab initio and MNDO calcns. have been performed to study the geometry and vibrational frequencies of nitromethane and the nitromethyl radical. For nitromethane the 2 rotational conformers are predicted to differ in energy by only 0.01 kcal/mol (MP2/6-31G*). Vibrational frequencies of the staggered and eclipsed conformations have been calcd. and compared with the exptl. frequencies. Similar studies were carried out for the nitromethyl radical where it was found that the UHF soln. was internally unstable, and a lower energy soln. was found with symmetry relaxation. However, the distortion from C2v is predicted to be energetically unfavorable when correlation is included (UMP2/3-21G). Vibrational frequencies of •CH2NO2 were calcd. at the C2v geometry and compared with a recent exptl. study. At the scaled 6-31G* level the av. abs. error in vibrational frequencies is 23 and 12 cm-1 for MeNO2 and •CH2NO2, resp., if the 2 NO stretches are omitted. The calcd. C-N stretching frequency of 995 cm-1 (scaled UHF/6-31G*) is only 48 cm-1 higher than the C-N stretch in MeNO2 and does not suggest significant π-bond character. Disagreement between calcd. and obsd. NO stretching frequencies is traced to the neglect of a contributing configuration. The MNDO results parallel 3-21G and 6-31G* results. However, when compared with exptl. values the 6-31G* basis is uniformly superior.
33. 33

    Cornaton, Y.; Ringholm, M.; Louant, O.; Ruud, K. Analytic Calculations of Anharmonic Infrared and Raman Vibrational Spectra. Phys. Chem. Chem. Phys. 2016, 18, 4201– 4215,  DOI: 10.1039/C5CP06657C

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    Analytic calculations of anharmonic infrared and Raman vibrational spectra

    Cornaton, Yann; Ringholm, Magnus; Louant, Orian; Ruud, Kenneth

    Physical Chemistry Chemical Physics (2016), 18 (5), 4201-4215CODEN: PPCPFQ; ISSN:1463-9076. (Royal Society of Chemistry)

    Using a recently developed recursive scheme for the calcn. of high-order geometric derivs. of frequency-dependent mol. properties, the authors present the 1st analytic calcns. of anharmonic IR and Raman spectra including anharmonicity both in the vibrational frequencies and in the IR and Raman intensities. In the case of anharmonic corrections to the Raman intensities, this involves the calcn. of 5th-order energy derivs.-i.e., the 3rd-order geometric derivs. of the frequency-dependent polarizability. The approach is applicable to both Hartree-Fock and Kohn-Sham d. functional theory. Using generalized vibrational perturbation theory to 2nd order, the authors have calcd. the anharmonic IR and Raman spectra of the non- and partially deuterated isotopomers of nitromethane, where the inclusion of anharmonic effects introduces combination and overtone bands that are obsd. in the exptl. spectra. For the major features of the spectra, the inclusion of anharmonicities in the calcn. of the vibrational frequencies is more important than anharmonic effects in the calcd. IR and Raman intensities. Using methanimine as a trial system, the analytic approach avoids errors in the calcd. spectra that may arise if numerical differentiation schemes are used.
34. 34

    Gorse, D.; Cavagnat, D.; Pesquer, M.; Lapouge, C. Theoretical and Spectroscopic Study of Asymmetric Methyl Rotor Dynamics in Gaseous Partially Deuterated Nitromethanes. J. Phys. Chem. A 1993, 97, 4262– 4269,  DOI: 10.1021/j100119a005

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    Brakaspathy, R.; Jothi, A.; Singh, S. Determination of Force Fields for Two Conformers of Nitromethane by CNDO/Force Method. Pramana - J. Phys. 1985, 25, 201– 209,  DOI: 10.1007/BF02847660

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    Mezey, P. G.; Kresge, A. J.; Csizmadia, I. G. A Theoretical Study on The stereochemistry and Protonation of -:CH2-NO2. Can. J. Chem. 1976, 54, 2526– 2533,  DOI: 10.1139/v76-358

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    A theoretical study on the stereochemistry and protonation of -:CH2-NO2

    Mezey, P. G.; Kresge, A. J.; Csizmadia, I. G.

    Canadian Journal of Chemistry (1976), 54 (16), 2526-33CODEN: CJCHAG; ISSN:0008-4042.

    The mol. conformation of -:CH2NO2 is found to be planar with an extremely shallow potential curve to pyramidal inversion, which suggests that suitable substituents could conceivable perturb the system into a pyramidal configuration corresponding to double min. on the potential surface and that a chiral carbanion might therefore exist. Rotating the NO2 group out of planarity by 90° raises the barrier to inversion at C by an appreciable amt. A Muliken population anal. gives a charge distribution in which a substantial portion of the neg. charge has shifted from C to O; this is consistent with the well-known tendency of nitronate ions to undergo simultaneous competitive protonation on C and O.
37. 37

    Vicente, A.; Antunes, R.; Almeida, D.; Franco, I. J. A.; Hoffmann, S. V.; Mason, N. J.; Eden, S.; Duflot, D.; Canneaux, S.; Delwiche, J. Photoabsorption Measurements and Theoretical Calculations of the Electronic State Spectroscopy of Propionic, Butyric, and Valeric Acids. Phys. Chem. Chem. Phys. 2009, 11, 5729– 5741,  DOI: 10.1039/b823500g

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    Photoabsorption measurements and theoretical calculations of the electronic state spectroscopy of propionic, butyric, and valeric acids

    Vicente, A.; Antunes, R.; Almeida, D.; Franco, I. J. A.; Hoffmann, S. V.; Mason, N. J.; Eden, S.; Duflot, D.; Canneaux, S.; Delwiche, J.; Hubin-Franskin, M.-J.; Limao-Vieira, P.

    Physical Chemistry Chemical Physics (2009), 11 (27), 5729-5741CODEN: PPCPFQ; ISSN:1463-9076. (Royal Society of Chemistry)

    Abs. photoabsorption cross sections of propionic (C2H5COOH), butyric (PrCOOH), and valeric (BuCOOH) acids were measured from the dissociative π* ← nO transition (beginning around 5.0 eV) up to 10.7 eV. This constitutes the 1st study of the neutral electronic states of propionic and butyric acids at energies above the π* ← nO band, while no previous spectroscopic data is available for valeric acid in the present range. The present assignments are supported by the 1st theor. calcns. of electronic transition energies and oscillator strengths for these org. acids. The excitation energies of the vibrational modes of propionic acid in its neutral electronic ground state and the vertical ionization energies of all three mols. were calcd. for the 1st time. The He(i) photoelectron spectroscopy of propionic acid was measured from 10 to 16 eV, revealing new fine structure in the 1st ionic band.
38. 38

    Moss, D. B.; Trentelman, K. A.; Houston, P. L. 193 nm Photodissociation Dynamics of Nitromethane. J. Chem. Phys. 1992, 96, 237– 247,  DOI: 10.1063/1.462510

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    The 193-nm photodissociation dynamics of nitromethane

    Moss, D. B.; Trentelman, K. A.; Houston, P. L.

    Journal of Chemical Physics (1992), 96 (1), 237-47CODEN: JCPSA6; ISSN:0021-9606.

    Multiphoton ionization spectroscopy and time-of-flight mass spectrometry have been used to det. nascent photofragment energy distributions for several of the products of the 193-nm photolysis of nitromethane. Internal energy distributions have been obtained for CH3 and NO(X2II), and translational energy distributions for CH3, NO(A2Σ+), and O(3P). The prodn. of two NO electronic states (X and A) and the appearance of two peaks in the translational energy distributions of the CH3 and O fragments are consistent with earlier proposals of a two-channel dissocn. He major channel produces CH3 and NO2(12B2), some of the latter having sufficient internal excitation to further dissoc. to NO(X) and O. The minor channel is believed to produce NO2 in a different electronic state which subsequently absorbs a second 193-nm photon and dissocs. to yield NO(A) and O. The major channel NO2 dissocn. dynamics are fit well by an impulsive model, while the minor channel apparently partitions much of the available energy into NO(A) vibration and/or rotation.
39. 39

    Butler, L. J.; Krajnovich, D.; Lee, Y. T. The Photodissociation of Nitromethane at 193 Nm. J. Chem. Phys. 1983, 79, 1708– 1722,  DOI: 10.1063/1.446015

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    The photodissociation of nitromethane at 193 nm

    Butler, L. J.; Krajnovich, D.; Lee, Y. T.; Ondrey, G.; Bersohn, R.

    Journal of Chemical Physics (1983), 79 (4), 1708-22CODEN: JCPSA6; ISSN:0021-9606.

    The dissocn. of nitromethane following the excitation of the π* → π transition at 193 nm was investigated by 2 independent and complementary techniques, product emission spectroscopy and mol. beam photofragment translational energy spectroscopy. The primary process was cleavage of the C-N bond to yield Me and NO2 radicals. The translational energy distribution for this chem. process indicates that there are 2 distinct mechanisms by which Me and NO2 radicals are produced. The dominant mechanism releasing a relatively large fraction of the total available energy to translation probably gives NO2 radicals in a vibrationally excited 2B2 state. When dissocd., other nitroalkanes exhibit the same emission spectrum as MeNO2, suggesting little transfer of energy from the excited NO2 group to the alkyl group during dissocn. for the dominant mechanism.
40. 40

    Lao, K. Q.; Jensen, E.; Kash, P. W.; Butler, L. J. Polarized Emission Spectroscopy of Photodissociating Nitromethane at 200 and 218 Nm. J. Chem. Phys. 1990, 93, 3958– 3969,  DOI: 10.1063/1.458781

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    Polarized emission spectroscopy of photodissociating nitromethane at 200 and 218 nm

    Lao, K. Q.; Jensen, E.; Kash, P. W.; Butler, L. J.

    Journal of Chemical Physics (1990), 93 (6), 3958-69CODEN: JCPSA6; ISSN:0021-9606.

    The polarized emission spectra of photodissociating nitromethane excited at 200 and 218 nm are reported. At both excitation wavelengths, the emission spectra show a strong progression in the NO2 sym. stretch; at 200 nm a weak progression in the NO2 sym. stretch in combination with one quantum in the C-N stretch also contributes to the spectra. The angular distribution was measured of emitted photons in the strong emission features from the relative intensity ratio between photons detected perpendicular to vs. along the direction of the elec. vector of the excitation laser. The anisotropy is substantially reduced from the 2:1 ratio expected for the pure nitromethane X(1A1) → 1B2(ππ*) → X(1A1) transition with no rotation of the mol. frame. The intensity ratios for the features in the NO2 sym. stretching progression lie near 1.5 to 1.6 for 200 nm excitation and 1.7 for 218 nm excitation. The anal. of the photon angular distribution measurements and consideration of the absorption spectrum indicate that the timescale of the dissocn. is too fast for mol. rotation to contribute significantly to the obsd. redn. in anisotropy. The detailed anal. of the results in conjunction with electron correlation arguments and past work on the absorption spectroscopy and final products' velocities results in a model which includes 2 dissocn. pathways for nitromethane, an electronic predissocn. pathway and a vibrational predissocn. pathway along the 1B2(ππ*) surface. The anal. suggests a reassignment of the minor dissocn. channel, first evidenced in photofragment velocity anal. expts. which detected a pathway producing slow CH3 fragments, to the near threshold dissocn. channel CH3 + NO2(2 2B2).
41. 41

    Yue, X. F.; Sun, J. L.; Wei, Q.; Yin, H. M.; Han, K. L. Photodissociation Dynamics of Nitromethane and Nitroethane at 266 Nm. Chin. J. Chem. Phys. 2007, 20, 401– 406,  DOI: 10.1088/1674-0068/20/04/401-406

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    Photodissociation dynamics of nitromethane and nitroethane at 266 nm

    Yue, Xian-fang; Sun, Ju-long; Wei, Qiang; Yin, Hong-ming; Han, Ke-li

    Chinese Journal of Chemical Physics (2007), 20 (4), 401-406CODEN: CJCPA6; ISSN:1003-7713. (Chinese Physical Society)

    Measurements of the nascent OH product from photodissocn. of gaseous nitromethane and nitroethane at 266 nm were performed using the single-photon laser induced fluorescence technique. The OH fragment is vibrationally cold for both systems. The rotational state distribution of nitromethane are Boltzmann, with rotational temp. of Trot = 2045 ± 150 and 1923 ± 150 K for both 2Π3/2 and 2Π1/2 states, resp. For nitroethane, the rotational state distribution shows none Boltzmann and cannot be well characterized by a rotational temp., which indicates the different mechanisms in producing OH radicals from photodissocn. of nitromethane and nitroethane. The rotational energy is calcd. as 14.36 ± 0.8 and 4.98 ± 0.8 kJ/mol for nitromethane and nitroethane, resp. A preferential population of the low spin-orbit component (2Π3/2) is obsd. for both nitromethane and nitroethane. The dominant population of Π+ state in two Λ-doublet states is also obsd. for both nitromethane and nitroethane, which indicates that the unpaired π lobe of the OH fragment is parallel to the plane of rotation.
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    Li, Y.; Sun, J.; Han, K.; He, G.; Li, Z. The Dynamics of NO Radical Formation in the UV 266 Nm Photodissociation of Nitroethane. Chem. Phys. Lett. 2006, 421, 232– 236,  DOI: 10.1016/j.cplett.2006.01.055

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    The dynamics of NO radical formation in the UV 266 nm photodissociation of nitroethane

    Li, Yamin; Sun, Julong; Han, Keli; He, Guozhong; Li, Zhuangjie

    Chemical Physics Letters (2006), 421 (1-3), 232-236CODEN: CHPLBC; ISSN:0009-2614. (Elsevier B.V.)

    Photodissocn. of gaseous nitroethane at 266 nm has been studied by monitoring the NO(X2Π) product using laser-induced fluorescence technique. Rotational state distributions of the NO(X2Π1/2 and X2Π3/2, v'' = 0) photofragment have been measured and characterized by Boltzmann temp. of 810 ± 100 K. Only the NO photoproduct in v'' = 0 state can be obsd. in the present work. The geometries of the nitroethane, the Et nitrite and the transition state connecting the two isomeric structures have been investigated using ab initio method. The photodissocn. dynamics of nitroethane is discussed on the basis of exptl. observation and calcn. results.
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    Keller-Rudek, H.; Moortgat, G. K.; Sander, R.; Sörensen, R. The MPI-Mainz UV/VIS Spectral Atlas of Gaseous Molecules of Atmospheric Interest. Earth Syst. Sci. Data 2013, 5, 365– 373,  DOI: 10.5194/essd-5-365-2013

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    Limão Vieira, P.; Eden, S.; Kendall, P. A.; Mason, N. J.; Hoffmann, S. V. VUV Photo-Absorption Cross-Section for CCl2F2. Chem. Phys. Lett. 2002, 364, 535– 541,  DOI: 10.1016/S0009-2614(02)01304-0

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    VUV photo-absorption cross-section for CCl2F2

    Limao Vieira, P.; Eden, S.; Kendall, P. A.; Mason, N. J.; Hoffmann, S. V.

    Chemical Physics Letters (2002), 364 (5,6), 535-541CODEN: CHPLBC; ISSN:0009-2614. (Elsevier Science B.V.)

    The photo-absorption spectrum of CCl2F2 has been measured using synchrotron radiation in the range 5.5-11 eV (225>λ>110 nm). Electronic state assignments have been suggested for each of the obsd. absorption bands incorporating both valence and Rydberg transitions. The high resoln. achieved has allowed vibrational series in one of these bands to be assigned for the first time. The measured VUV cross-sections may be used to derive the photolysis rate of CCl2F2 in the terrestrial atm.
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    Chemical Kinetics and Photochemical Data for Use in Stratospheric Modelling, Evaluation Number 12, NASA, Jet Propulsion Laboratory, JPL, Publication 97-4, January 15; 1997.

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