Simple quantum models for atom-polyatomic (V, T) collisional energy transfers: an exploratory study

Abstract

A general quantum model for treating vibrational relaxation in polyatomic molecules is presented and its application to CO2 relaxation in collision with helium is discussed. A drastic simplification of the large expansion over molecular states, which is usually needed for complex targets, is here achieved by treating each normal mode independently and by then coupling each manifold of levels via the intermolecular potential through an analytic expansion of the latter that yields simple expressions for the coupling matrix elements. The effects of the physical factors which are here disregarded and/or simplified by the model are discussed and qualitatively assessed by comparison with previous calculations on the same system.