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

¹ Department of Theoretical Physics and Astronomy, Herzen University, St. Petersburg 191186, Russia and Max-Planck Institute for Astrophysics, Postfach 1371, 85741 Garching, Germany
e-mail: andrey.k.belyaev@gmail.com
² Charles University in Prague, Faculty of Mathematics and Physics, Department of Chemical Physics and Optics, Ke Karlovu 3, 12116 Prague 2, Czech Republic
³ Max-Planck Institute for Astrophysics, Postfach 1371, 85741 Garching, Germany

Received: 5 February 2014
Accepted: 12 March 2014

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 ^1,3Σ⁺ and ^1,3Π 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 ³S) 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.