Polarization and Angular Distribution of L? X-Ray Following Inner-Shell 2p_3/2 Photoionization of Magnesium-Like Ions

The inner-shell 2p_3/2 photoionization and the subsequent decay of Mg-like Fe¹⁴⁺, Cd³⁶⁺, W⁶²⁺ and U⁸⁰⁺ ions are studied theoretically within the multiconfiguration Dirac–Fock method and the density matrix theory. Special attention is paid to exploring the influence of the non-dipole terms which arise from the multipole expansion of the electron-photon interaction in the photoionization process. The results show that the non-dipole contribution to the total cross section, the magnetic sublevels cross section of the photoionization process, the degree of linear polarization and angular distribution of the subsequent characteristic x-ray radiation become more important with the increase of photons energy and atomic nuclear Z. Especially for the cross section and the degree of linear polarization, the non-dipole contribution arrives at 50% for U⁸⁰⁺ at four time energy threshold units. However, for the angular distribution, the maximum contribution does not exceed 4%, even for U⁸⁰⁺ ions.