DoubleK-shell photoionization of atomic beryllium

Abstract

Double photoionization of the core $1s$ electrons in atomic beryllium is theoretically studied using a hybrid approach that combines orbital and grid-based representations of the Hamiltonian. The ${}^{1}\phantom{\rule{-0.16em}{0ex}}S$ ground state and ${}^{1}\phantom{\rule{-0.16em}{0ex}}P$ final state contain a double occupancy of the $2s$ valence shell in all configurations used to represent the correlated wave function. Triply differential cross sections are evaluated, with particular attention focused on a comparison of the effects of scattering the ejected electrons through the spherically symmetric valence shell with similar cross sections for helium, representing a purely two-electron target with an analogous initial-state configuration.