QUANTUM NUMBER AND TEMPERATURE-DEPENDENCE OF FOREIGN GAS-BROADENING COEFFICIENTS IN THE NU(1) AND NU(3) BANDS OF SO2 - COLLISIONS WITH H-2,AIR, HE, NE, AR, KR, AND XE

To complete our studies concerning collisional line broadening in the fundamental bands of SO2, hydrogen-broadening coefficients for 21 line s from the v(3) band between 1341 and 1357 cm(-1) with 8 less than or equal to J '' less than or equal to 33, 1 less than or equal to K-a '' less than or equal to 16, helium-broadening coefficients for 3 lines from the v(1) band around 1121 cm(-1) with 8 less than or equal to J ' ' less than or equal to 36, 7 less than or equal to K-a '' less than o r equal to 9, and xenon-broadening coefficients for 6 lines from the v (3) band between 1321 and 1366 cm(-1) with 4 less than or equal to J ' ' less than or equal to 61, 0 less than or equal to K-a '' less than o r equal to 6 and 15 lines from the v(1) band between 1072 and 1140 cm( -1) were measured at room temperature applying a high-resolution lead- salt diode laser spectrometer. For collisions with noble gases the tem perature dependence in the range between 252 and 362 K was studied for three lines from the v(3) band. For the same temperature interval the air-broadening coefficients of seven lines from the v(3) band were de termined. The hydrogen-broadening coefficients are larger than those p reviously published for air broadening, but show the same quantum numb er dependence. A weak maximum in the K-a '' dependence and no trend in the J '' dependence are observable. In contrast to this and to the we ll-studied quantum number dependence of the self-broadening coefficien ts a more pronounced J '' dependence but no significant K-a '' depende nce was measured in the case of collisions with noble gas perturbers. Temperature exponents of 0.72 less than or equal to n less than or equ al to 0.99 (average value 0.83) for the air-broadening coefficients we re observed. The smaller exponent of about 0.7 determined for noble ga s collisions is in good agreement with theory. Due to the large uncert ainties for the n values caused by the restricted temperature range a perturber dependence can only be supposed. Nevertheless, the data are close to the theoretical prediction. (C) 1997 Academic Press.