Relativistic theory of the double photoionization of helium-like atoms

TL;DR

This paper presents a comprehensive relativistic calculation of double photoionization in helium-like atoms, highlighting the importance of relativistic effects even in medium-Z ions and their impact on cross section ratios.

Contribution

It introduces a fully relativistic approach using partial-wave Dirac states, including retardation and higher multipoles, to improve accuracy in modeling double photoionization.

Findings

Relativistic effects significantly alter the photon energy dependence of cross sections.

The approach accounts for electron-electron interactions to leading order.

Results show notable differences from non-relativistic predictions.

Abstract

A fully relativistic calculation of the double photoionization of helium-like atoms is presented. The approach is based on the partial-wave representation of the Dirac continuum states and accounts for the retardation in the electron-electron interaction as well as the higher-order multipoles of the absorbed photon. The electron-electron interaction is taken into account to the leading order of perturbation theory. The relativistic effects are shown to become prominent already for the medium-Z ions, changing the shape and the asymptotic behaviour of the photon energy dependence of the ratio of the double-to-single photoionization cross section.