DISCRETE STRUCTURE IN THE 4D PHOTOABSORPTION SPECTRUM OF CS+

The photoabsorption spectrum of Xe-like Cs+ has been obtained in the X UV spectral region with the dual-laser-produced plasma (DLP) technique . Photoexcitation from the 4d subshell is the dominant process in the 80-150 eV energy range and is intermediate in behaviour between the we ll documented cases of Xe and Ba2+. Between 80 and 90 eV discrete stru cture, corresponding to 4d--> np, n(1)f(n greater than or equal to 6, n(1) greater than or equal to 4) transitions is obtained, while above 90 eV the spectrum is dominated by an intense 4d --> epsilon f resonan ce. Multiconfiguration Hartree-Fock (MCHF) calculations facilitated id entification of the majority of the features observed.