A classical ensemble model of three-body collisions in the point contact approximation and application to alignment effects in near-resonant energy transfer collisions of He atoms with Rydberg Ca atoms

Abstract

A classical ensemble model of three-body energy transfer in the point contact approximation is presented. This model yields cross sections for transitions between initial and final states defined by energy, magnitude of angular momentum, and projection of angular momentum along an axis of spatial quantization corresponding to the quantum numbers of the initial and final stationary states, n,l,m and n′,l′,m′. Using a cross section that is differential in the final-state quantum numbers, the spatial constraints imposed by conservation of energy and angular momentum can be investigated even for comparatively small quantum numbers. When applied to the Ca(17d)+He→Ca(18p)+He energy transfer processes, the model sheds light on recently discovered alignment phenomena in collisions of rare-gas atoms with initially aligned Rydberg atoms. Materials for the implementation of this model are available from the authors via the Internet.