One- and two-photon ionization of model atoms

Abstract

The response to an ionizing radiation field of a simple one-electron atomic system modelled by an attractive Fermi-type pseudopotential is investigated under the assumption that the source intensity is sufficiently low for a perturbation theory treatment at appropriate order to be adequate in dealing with the radiation field-matter interaction. One- and two-photon ionization cross-sections are evaluated either in the length or in the velocity forms by using an approach recently put forward by the authors, which stresses the nature of such quantities as Fourier transforms of relevant time-dependent correlation functions. Some remarks concerning the merits of different gauges in approximate two-photon ionization cross-section calculations conclude the paper.