Quantum mechanical study of elastic scattering and rotational excitation of CO by electrons

Abstract

We report close coupling calculations of differential, integral, and momentum transfer cross sections for pure elastic scattering and rotational excitation of CO by electron impact. The calculations are based on a static charge distribution that has correct dipole and quadrupole moments, has cusps at the nuclei, and is augmented by an SCF treatment of charge polarization and a local approximation for exchange. The rotationally summed cross sections, with no adjustable parameters in the scattering calculation, are in reasonably good agreement with the experimental cross sections but are somewhat larger at small scattering angles. The state-to-state differential cross sections show several interesting features, including very large contributions to small-angle scattering from large angular momenta and a ’’propensity rule’’ favoring even Δj over odd Δj at almost all scattering angles for Δj≲4 where Δj is the change in rotational quantum number.