Quantum Number and Temperature Dependence of Foreign Gas-Broadening Coefficients in the ν1and ν3Bands of SO2: Collisions with H2, Air, He, Ne, Ar, Kr, and Xe

Abstract

To complete our studies concerning collisional line broadening in the fundamental bands of SO2, hydrogen-broadening coefficients for 21 lines from the ν3band between 1341 and 1357 cm−1with 8 ≤J″ ≤ 33, 1 ≤Ka″≤ 16, helium-broadening coefficients for 3 lines from the ν1band around 1121 cm−1with 8 ≤J″ ≤ 36, 7 ≤Ka″≤ 9, and xenon-broadening coefficients for 6 lines from the ν3band between 1321 and 1366 cm−1with 4 ≤J″ ≤ 61, 0 ≤Ka″≤ 6 and 15 lines from the ν1band between 1072 and 1140 cm−1were measured at room temperature applying a high-resolution lead-salt diode laser spectrometer. For collisions with noble gases the temperature dependence in the range between 252 and 362 K was studied for three lines from the ν3band. For the same temperature interval the air-broadening coefficients of seven lines from the ν3band were determined. The hydrogen-broadening coefficients are larger than those previously published for air broadening, but show the same quantum number dependence. A weak maximum in theKa″dependence and no trend in theJ″ dependence are observable. In contrast to this and to the well-studied quantum number dependence of the self-broadening coefficients a more pronouncedJ″ dependence but no significantKa″dependence was measured in the case of collisions with noble gas perturbers. Temperature exponents of 0.72 ≤n≤ 0.99 (average value 0.83) for the air-broadening coefficients were observed. The smaller exponent of about 0.7 determined for noble gas collisions is in good agreement with theory. Due to the large uncertainties for thenvalues caused by the restricted temperature range a perturber dependence can only be supposed. Nevertheless, the data are close to the theoretical prediction.