High‐resolution photoabsorption cross‐section measurements of SO₂ at 295 K between 198 and 220 nm

Abstract

SO 2 is an important constituent of the atmospheres of Io and Venus. Accurate photoabsorption cross‐section data at the temperatures of these planetary atmospheres are required for the interpretation of SO 2 observations and for reliable photochemical models. As part of a planned series of measurements over the 160–300 K range, photoabsorption cross sections of SO 2 at 295 K, in the wavelength region 198–220 nm, have been determined from very high resolution (resolving power (λ/Δλ) ≈ 450,000) absorption spectra recorded with a vacuum ultraviolet Fourier transform spectrometer. These new measurements are compared with earlier, lower‐resolution (λ/Δλ ≈ 100,000) photoabsorption measurements at 213 K spanning the same wavelength region, with lower‐resolution (λ/Δλ ≈ 100,000) measurements at 295 K in a more limited region, and with a recent Doppler‐limited laser diode measurement at 295 K over a very narrow wavelength region.