Ionisation of atoms by ion impact

Abstract

Total cross sections are calculated for the ionisation of a hydrogen atom by multicharged fully-stripped ions in the 20-1000 keV amu-1 impact energy range. Distortion is accounted for in the entrance channel (via the eikonal approximation) and in the exit channel (via the continuum distorted-wave approximation). The transition amplitude is calculated in the post form so that the electronic nonorthogonal kinetic energy is treated as the perturbation. It is concluded that of the currently available models this theory is the most successful and versatile over a considerable range of energies and charges. Specifically for ionisation of a hydrogen atom by 50 keV protons the authors present doubly differential cross sections for electrons ejected in the forward direction and singly differential cross sections as a function of emission energy. The question of cusps and peaks in the differential cross sections is considered as is the question of charged scaling of the total cross section.