Non-radiative inelastic processes in lithium-helium ion-atom collisions

Abstract

Aims. The aims are to estimate efficiencies of non-radiative inelastic processes in lithium-helium ion-atom collisions and to compare them to those for radiative processes. Methods. Non-radiative inelastic cross-sections and rate coefficients for different lithium-helium ion-atom collisions are estimated by means of the recently proposed branching probability current method, which is based on the accurate ab initio adiabatic Born-Oppenheimer potentials that have been recently calculated for the low-lying 1,3 Σ+ and 1,3 Π states of the LiHe+ ion.Results. It is shown that at low temperatures the radiative depopulation in Li+ + He and Li + He+ collisions dominates over the non-radiative processes, while in Li+ + He(2s 3 S) collisions the non-radiative processes dominate over the radiative association at temperatures above 3000 K, which can be expected to have some influence on depopulations of metastable He in high temperature astrophysical environments.