2015MNRAS.449.3323B

A full quantum study of non-radiative inelastic processes in lithium-helium ion-atom collisions is presented. The study uses the 13 lowest-lying electronic molecular states of LiHe+ of the 1Σ+, 3Σ+, 1Π, and 3Π symmetries. Radial non-adiabatic coupling matrix elements between states of the same symmetry are calculated. Quantum non-adiabatic nuclear dynamics is studied by the reprojection method, which takes into account all non-adiabatic couplings, including those that exhibit non-vanishing asymptotic values. The energy dependence of the cross-sections and temperature dependence of the rate coefficients for all partial processes between the scattering channels is determined. It is shown that the temperature dependence of rate coefficients for the non-radiative and the radiative processes behave differently: the non-radiative rate coefficients increase with increasing temperature, while the radiative rate coefficients decrease. Consequently, in the depopulation of the same scattering channel the non-radiative processes dominate in high-temperature environments, whereas at low temperature, such as in interstellar molecular clouds, the radiative processes are typically more efficient.