Photoionization, photoexcitation and photofragmentation of caesium halide dimers

Abstract

Ion time-of-flight spectra, total and partial ion yield spectra were measured from the vapours of CsCl and CsBr, containing both monomer and dimer molecules. VUV radiation ranging from 7 to 20 eV was used, covering the valence ionization thresholds and the resonant excitations in Cs+. The electronic and nuclear relaxation processes in the caesium halide dimer molecules are studied, using the yields of several molecular and fragment ions together with atomic ab initio calculations based on the ionic model. The electronic decay processes that occur in the caesium halide dimers are identified together with their specific fragmentation pathways. It is shown that the dominant relaxation mechanism changes across the excitation spectrum.