A simple numerical model of vibrational energy transfer in polyatomic gases

Abstract

A numerical procedure is developed for the accurate modelling of vibrational-vibrational and vibrational-translational energy transfer in molecular gases. The harmonic approximation necessary for an analytical solution is unnecessary and experimentally observed level energies are used. Rate constants, deduced by curve fitting results from this model to thermal lens data, are significantly different from those deduced from an analytical solution, e.g. for CO 2, k 1=350 Torr −1 s −1 and k 2 = 370 Torr −1 s −1 for the scheme CO 2(010) + CO 2(000) ⇌ CO 2(000) + CO 2(000), Δ H = − 667 cm −1 and CO 2(001) + CO 2(OOO) ⇌ CO 2 (030) + CO 2(000), Δ H = −417 cm −1, where k 1 and k 2 are the rate constants for the forward processes.