Theoretical investigation of electron transfer and detachment processes in low energy H− + Li and Li− + H collisions

Abstract

The charge exchange and collisional detachment processes in H− + Li and Li− + H collisions have been studied by using the quantal molecular orbital close-coupling (QMOCC) method in the energy ranges of about 0.12–1000 eV u−1 and 0.1 meV–1000 eV, respectively, and the inelastic collision cross sections and rate coefficients have been computed and presented. It is found that the electron transfer process in the H− + Li and Li− + H collisions is due to the Demkov coupling between the 12Σ+ and 22Σ+ states at internuclear distances of about 15a0. The collisional electron detachment in the considered collision system is due to the excitation of the remaining six states, which are all unstable against autodetachment. These states are populated through a series of Landau–Zener couplings of the 22Σ+ state with upper 2Σ+ states and by the rotational 2Σ+–2Π couplings at small internuclear distances. The cross sections for electron transfer in H− + Li and Li− + H collisions in the energy range of 10–1000 eV u−1 attain values in the range of 10−16–10−15 cm2 (reaching their maximum values of about 5 × 10−15 cm2 at 500–600 eV u−1), while the values of the corresponding electron detachment cross sections in this energy range attain generally smaller values.