5s photoionization cross section of atomic Ba

Figure 1. 5s photoionization cross section of atomic Ba.

Abstract

The photoionization of Ba 5s in the high-energy Cooper minimum region has been investigated using the relativistic-random-phase approximation and the relativistic-random-phase approximation with relaxation. Comparison with recent experiment shows good agreement for the total cross section, but only qualitative agreement for the photoelectron angular distribution asymmetry parameter, β. The disagreement was traced to the omission of photoionization-plus-excitation channels arising from the 4d subshell.