Photoabsorption and dissociation of ArXe#+ and Kr#Xe+ molecular ions by electron impact

Abstract: We discuss some optical and kinetic properties of heavy heteronuclear ions of rare gases ArXe⁺ and KrXe⁺ formed in a plasma of rare gas mixtures. Various types of nonadiabatic phototransitions between the ground and excited electronic terms of such ions, accompanied by a charge exchange, are considered. The contributions of bound–free (photodissociation) and bound–bound phototransitions to the total photoabsorption coefficient are analysed under conditions of thermal excitation of the entire rovibrational quasi-continuum. The contributions of free–free and free–bound (photoassociation) transitions to photoabsorption are calculated. The results of calculations of the effective cross sections and rate constants of the processes of continuous absorption of radiation in the visible and UV ranges by ArXe⁺ and KrXe⁺ ions at different temperatures of the heavy particle component of the plasma are presented. We also consider the resonant mechanism of destruction of ArXe⁺ and KrXe⁺ ions by electron impact via processes of dissociative recombination and direct dissociative excitation. The analysis carried out in this work refines the physical pattern of radiative and collisional processes in plasmas of inert gas mixtures Rg/Xe (Rg = Ar, Kr) excited by an electron beam, in gas discharges and under optical pumping. The results obtained are of interest for developing the kinetic models of active media for gas and plasma lasers, UV radiation sources, excilamps, and arrays of microplasma cells.

Keywords: inert gas mixtures, heteronucler molecular ions, radiative and collisional processes, continuous absorption of electromagnetic radiation, photodissociation and photoassociation, bound–bound and bound–free radiative transitions, dissociative recombination of electrons with ions, dissociative excitation.