A b i n i t i o study of H2 dissociation and vibrational relaxation in mixtures of He and Ar: Implications for the linear mixture rule

Abstract

The master equation for the thermal dissociation and vibrational relaxation of H2 infinitely dilute in mixtures of He and Ar was solved using rotationally averaged rate constants from previous ab initio studies on H2/He and H2/Ar. The calculated rate constants for dissociation, kd, vibrational relaxation times, τ, and induction times for dissociation, ti, for the mixtures were compared to those predicted by the linear mixture rule: kLMR=Σixiki, where xi is the mole fraction of gas i and ki is the rate constant for the process in pure component i. Substantial deviations were found to occur, with the greatest deviations occurring for kd. Further analysis indicates that the deviations arise due to differing efficiencies for multiquantum transitions in H2/He and H2/Ar.