Quantal theory of shifted thresholds for the excitation of autoionizing states

Abstract

The formalism developed for resonant scattering of electrons by molecules is used to describe the decay of an autoionizing atomic state excited by a slowly moving electron. It is predicted that the energy of the ejected electron should be shifted, as observed by the Manchester electron-scattering group. A simple calculation gives reasonable quantitative agreement with the experiments. When the scattered electron is much slower than the ejected electron, a semiclassical 'post-collision' model appears to be valid. The deviations from this model, which appear for more energetic scattered electrons, are explained as due to a screening of the ionic field by the ejected electron.