Theoretical study on decay of the 4d core-excited states of Cs III

In a recent XUV photoabsorption spectrum of Cs III ions by Cummings and O'Sullivan 2001 J. Phys. B 34 199, rather large linewidths were found for the \rm 4d^\,9 \rm 5s^2 \rm 5p^6 \,- \,\rm 4d^\,10 \rm 5s^2 \rm 5p^5 transition which are quite in disagreement with corresponding quasi-relativistic multiconfiguration Hartree--Fock (MCHF) calculation. In the present work, a detailed multiconfiguration Dirac-Fock study has been carried out to explore this discrepancy. Owing to the detailed consideration of electron correlation effects, some 'forbidden' Auger decay channels, such as \rm 4d^\,10 \rm 5s^2 \rm 5p^3 \rm 5d and \rm 4d^\,10 \rm 5s^0 \rm 5p^6 , would become `open'. As a result, remarkable improvement of the linewidths has been obtained in our calculation. Furthermore, the theoretical Auger spectrum of the \rm 4d^\,9 \rm 5s^2 \rm 5p^6 core-excited states of Cs III ions is given in the present work.