Regular Article

Inelastic processes in collisions of lithium positive ions with hydrogen anions and atoms^★

¹ Department of Theoretical Physics and Astronomy, Herzen University, St. Petersburg 191186, Russia
² Max-Planck Institute for Astrophysics, Postfach 1371, 85741 Garching, Germany

^a e-mail: andrey.k.belyaev@gmail.com

Received: 10 June 2017
Received in final form: 9 August 2017
Published online: 7 November 2017

Abstract

Inelastic processes in the low-energy collisions Li³⁺ + H⁻, Li²⁺ + H, Li²⁺ + H^- and Li⁺ + H are investigated for all collisional channels with the excited ionic lithium states Li²⁺ (nl) and Li⁺ (1s nl) up to and including the corresponding ion-pair states for the temperature range 1000–20 000 K. For all possible processes in the Li³⁺ + H^- and Li²⁺ + H collisions inelastic cross sections and rate coefficients are calculated for the transitions between the ion-pair channel Li³⁺ + H^- and the 35 below lying contributing Li²⁺ (nl) + H channels. It is found that the highest values of cross sections and rate coefficients are obtained for the recombination processes and their inverse, the ion-pair formation processes, involving the Li²⁺ (3l), Li²⁺ (4l), and Li²⁺ (5l) states. For the processes in the Li²⁺ + H^- and Li⁺ + H collisions, cross sections and rate coefficients are calculated for all transitions between 34 Li⁺ (1s nl) + H channels lying below Li²⁺ + H^- plus this ion-pair channel. In this case the highest rate coefficients correspond to the recombination processes with the Li⁺(1s3l ^1,3L) and Li⁺(1s4l ^1,3L) final states, as well as their inverse processes of ion-pair production. Rate coefficient values for these most efficient processes are rather high, of the order of 10⁻⁸ cm³/s. This leads to total recombination rate coefficients in Li³⁺ + H^- and Li²⁺ + H^- collisions with values larger than 10⁻⁷ cm³/s.