The theory of coincidence experiments on electron impact ionisation of inner atomic shells

Abstract

A theoretical treatment is given of possible experiments on electron impact ionisation of inner atomic shells, in which an inelastically scattered electron is detected in coincidence with the decay products of the ion formed, namely with an X-ray photon or with an Auger electron. General expressions for the angular distribution and polarisation of the X-ray photons and Auger electrons are given in terms of the parameters describing the anisotropy of the ionic state, namely statistical tensors which depend on the electron scattering angle and are determined by the ionisation mechanism. The statistical tensors, the asymmetry and the polarisation of the X-rays and the asymmetry of the Auger electrons are calculated for ionisation of the 2p shell of Ar, the 3d shell of Kr and the 4d shell of Xe at different scattering angles of the fast electron.