Collective Auger Decay of 4d−2 Double Inner-Shell Vacancy in Xe

Auger decay of all levels of the double core-hole states 4d−2 of Xe2+, including collective Auger decay (CAD) pathways, is investigated using the relativistic distorted-wave approximation. Large-scale configuration interaction calculations were performed to obtain level-to-level Auger decay rates. In addition to the typical Auger decay final levels associated with the configurations of 4d−15s25p4, 4d−15s15p5, and 4d−15s05p6, evident contributions are identified from excited channels, leading to configurations such as 4d94f15s25p3, 4d95s25p35d1, 4d95s25p36s1, and 4d95s25p36p1. These contributions arise from strong electron correlation between the valence electronic orbitals and the 4d inner-shell orbital. The CAD rates and branching ratios (BRs) are determined for each double core-hole level with a minimum CAD BR of 1.28% and a maximum of 4.08% among all CAD channels. The configuration-averaged CAD BR is predicted to be 1.93%, which helps explain recent unexplained experimental findings. The inclusion of CAD processes enriches Auger electron spectroscopy, thereby extending potential applications of this important experimental tool in both fundamental and applied research.