Electron-correlation-induced interchange of lifetime broadenings of5s−1multiplet states in atomic Cs

Abstract

The lifetime broadenings of the most intense $5s$ photolines of Cs were studied. The aim of this study was to understand the origin of the remarkable differences in the lifetime widths of different $5{s}^{\ensuremath{-}1}$ multiplet states. The $5s$ photoelectron spectra of the $6s\ensuremath{\rightarrow}6{p}_{1/2,3/2}$ laser-excited states are presented in the binding energy region of 30--34 eV showing the main $5s$ photolines of the ground state and laser-excited states as well as the $5s5{p}^{6}6p$ shakeup satellites. The lifetime widths of the states were determined. The Hartree-Fock calculations were carried out to predict the $5s$ photoelectron spectrum. The lifetime broadenings of the $5s$ photolines were found to be due to the transition rates of the subsequent Coster-Kronig transitions to the $5{s}^{2}5{p}^{5}$ states. It was found that a straightforward single-configuration explanation cannot be given for the lifetime differences. Instead, electron correlation plays an essential role and the lifetime broadenings were found to be predicted well only when configuration interaction between the $5{s}^{\ensuremath{-}1}$ and $5{p}^{\ensuremath{-}2}5d$ configurations is taking into account.