Web Release Date: May 8,
Temperature and Pressure Dependence of High-Resolution Air-Broadened Absorption Cross Sections of NO2 (415-525 nm)
Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125
Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109
Received: February 5, 2004
In Final Form: March 24, 2004
Abstract:
Cross sections of air-broadened NO2 in the 415-525 nm region are reported. These are retrieved from 21
absorption spectra recorded at 0.060 cm-1 resolution with the McMath-Pierce Fourier Transform Spectrometer
located on Kitt Peak in Arizona. The measurements are obtained for pressures (1-760 Torr) and temperatures
(220-298 K) that are representative of typical tropospheric and stratospheric conditions. Two sigma uncertainty
(95% confidence interval 
2
mean) for the absolute absorption cross sections is below ±7% over the reported
wavelength range. The average integrated intensity of all our data is <>400-500 nm = 4.53 × 10-17 cm2 nm,
which is within 0.2% of the averaged value from the recent literature. The wavelength (referred to vacuum)
accuracy is 0.011 cm-1 (2.8 × 10-4 nm at 500 nm) and precision is 0.0022 cm-1 throughout the investigated
wavelength range. In agreement with previous observations, high-resolution features in the NO2 absorption
spectrum display a strong pressure dependence with an effective pressure broadening parameter of 0.116 ±
0.003 cm-1/atm (the rate of increase of Lorentzian half width at half-maximum with pressure). Temperature
has a relatively minor effect on the shapes of individual high-resolution features, but it exerts a complex
dependence on the relative line intensities. Absorption cross sections reported here represent the highest
resolution data available over a substantial (>100 nm) wavelength range for quantitative analysis of NO2
atmospheric column absorption spectra.
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