Photoionization of the Be isoelectronic sequence: total cross sections

TL;DR

This study calculates total photoionization cross sections for beryllium-like ions across a wide range of elements, comparing nonrelativistic and relativistic methods, and finds good agreement with experimental data.

Contribution

It provides comprehensive cross section data for the Be-like isoelectronic sequence using both LS-coupling and Breit-Pauli R-matrix methods, highlighting relativistic effects.

Findings

Good agreement with experimental data for several ions.

Relativistic effects significantly influence cross sections.

Comparison between LS and BP results elucidates relativistic impacts.

Abstract

The photoionization of the four-electron beryllium-like isoelectronic series from the neutral to Fe^{+22} has been studied for ground ^1S and metastable ^3P initial states. The wave functions of the final-state (target) ions were built using the CIV3 code. Both nonrelativistic LS-coupling R-matrix and relativistic Breit-Pauli (BP) R-matrix methods were used to calculate the cross sections in the photon-energy range between the first ionization threshold and the 1s^2 4f_{7/2} threshold for each ion. Our total cross sections compare well with experiment which is available for Be, B^+, C^{+2}, N^{+3}, and O^{+4}. The agreement between the present work and previous calculations is discussed in detail. The importance of relativistic effects is seen by the comparison between the LS and the BP results.