Photo-Ionization of Lithium: A Many-Body Calculation

Abstract

The photo-ionization cross section $a_{\nu }$ of lithium has been calculated to second order in Brueckner-Goldstone perturbation theory with Hartree-Fock as zero order, for ejected electron energies in the range $0<~k^2<~0.36$ Ry. Other Hartree-Fock calculations of $a_{\nu }$ are analyzed using certain new theorems relating alternative forms of the matrix element. The final second-order perturbed values of $a_{\nu }$ in the length and velocity formulations are in good agreement with experiment throughout the energy range studied.