The Scattering of Slow Electrons by Atoms

Abstract

A new approximation is proposed for calculating cross sections for the scattering of slow electrons by atoms. Although the proposed approximation embodies the essential feature of Born's approximation it is compatible with the exclusion principle for electrons, and yields nonvanishing cross sections for the excitation by electron impact of intersystem transitions in normal-coupling atoms. Unlike Oppenheimer's approximation it yields unambiguous results when approximate atomic wave functions are used in the calculation of excitation cross sections, provided that these wave functions belong to a single hermitian operator that differs from the exact hamiltonian only through a term in the potential energy.