Quantum Scattering Calculations for H2S-He between 1-600 K in Comparison with Pressure Broadening, Shift, and Time Resolved Double Resonance Experiments

Christopher D. Ball, Markus Mengel, Frank C. De Lucia, and David E. Woon

J. Chem. Phys. 111: 8893-8903 (1999)

Abstract

We have performed quantum scattering calculations to predict pressure broadening, pressure shift, and inelastic depopulation cross-sections for the rotational transitions 11,0<-10,1 and 22.0<-21.1 of the H2S molecule in collision with helium atoms over a temperature range from 1 to 600 K. The calculated cross-sections are compared with experimental values obtained by millimeter wave spectroscopic techniques and the collisional cooling method. We observe good agreement between theory and experiment over the temperature region from 20 to 600 K, but increasing differences below 20 K. Possible reasons for the deviations at lower temperatures are discussed. The calculations also illustrate the contribution of elastic collisions to the pressure broadening cross-sections. Copyright © 1999 American Institute of Physics.