A high energy approximation. II. Hydrogen atom excitation by electrons

Abstract

For pt. I see ibid., vol.4, no.10, 1288 (1971). The cross sections for the excitation of the 2s, 2p, and 3s states of hydrogen by electron impact are evaluated at high energy in a first order approximation in which the interaction between the incident electron and target proton is represented by a Coulomb wave final state in the T matrix. In the usual Born approximation this interaction has a vanishing contribution because of the orthogonality of the atomic states. The evaluated total cross sections converge to the Born result at high energies, but the differential cross sections at large angles show marked disagreement with the Born approximation and reasonable agreement with experiment. It is concluded that for non-forward inelastic scattering the Born approximation does not converge to the correct result in the high energy limit.