A multiple hard-ellipsoid model for rotationally inelastic collisions

Abstract

A multiple hard-ellipsoid model is developed to describe atom–diatom rotationally inelastic collisons. The model is designed to be used for ‘soft’ and anisotropic repulsive intermolecular potentials for which single hard-shape models fail to reproduce the integral cross-sections. It is shown for the Na₂–He system that a small number of ellipsoids representing different regions of the repulsive intermolecular potential can be used within a classically impulsive approximation to reproduce the intergral J= 0 →J′ cross-sections. The model facilitates investigation of how different regions of the intermolecular potential contribute to rotationally inelastic scattering processes.