Sudden Approximation Applied to Rotational Excitation of Molecules by Atoms. I. Low-Angle Scattering

Abstract

The sudden approximation is applied to the calculation of transition probabilities and cross sections for rotational excitation and scattering of homonuclear diatomic molecules by atoms. The present analysis is restricted to a consideration of the influence of the anisotropy and strength of the long-range attractive part of the interaction potential on the scattering at low angles. Nevertheless, the results illustrate the main features of the method applied to inelastic molecular collisions in general, and demonstrate its advantage over the first-order perturbation approximation. Measurements of low-angle differential inelastic scattering cross sections would yield directly the anisotropy of the long-range attractive potential.