Approximate cross sections for optically disallowed excitation of atoms by electrons

Abstract

Formulae for approximate calculation of excitation cross sections for optically disallowed transitions are discussed. It is shown that the formula previously given by Drawin can be used in a different manner than pointed out by this author. This different manner seems to give reasonably accurate cross sections for small energies of the incident electrons, and gives the correct high energy limit. A comparison is made between approximate cross sections calculated here and already known Born cross sections.