Quantum scattering calculations for H2S-He between 1-600 K in comparison with pressure broadening, shift, and time resolved double resonance experiments
Cd. Ball et al., Quantum scattering calculations for H2S-He between 1-600 K in comparison with pressure broadening, shift, and time resolved double resonance experiments, J CHEM PHYS, 111(19), 1999, pp. 8893-8903
We have performed quantum scattering calculations to predict pressure broad
ening, pressure shift, and inelastic depopulation cross-sections for the ro
tational transitions 1(1,0)<-- 1(0,1) and 2(2,0)<-- 2(1,1) of the H2S molec
ule in collision with helium atoms over a temperature range from 1 to 600 K
. The calculated cross-sections are compared with experimental values obtai
ned by millimeter wave spectroscopic techniques and the collisional cooling
method. We observe good agreement between theory and experiment over the t
emperature region from 20 to 600 K, but increasing differences below 20 K.
Possible reasons for the deviations at lower temperatures are discussed. Th
e calculations also illustrate the contribution of elastic collisions to th
e pressure broadening cross-sections. (C) 1999 American Institute of Physic
s. [S0021-9606(99)01143-5].