Charge transfer in cold collisions of rubidium atoms with calcium and ytterbium ions

Abstract

Low-energy collisions of the Ca and Yb cations with Rb atoms are investigated theoretically using accurate ab initio potential energy curves and coupling matrix elements to elucidate the dominant charge transfer mechanisms. The cross sections calculated at collision energies above 10−5 cm−1 exhibit the features typical to Langevin ion-atom collision regime, including a rich structure associated with the centrifugal barrier tunnelling (orbiting) resonances. It is shown that the dominant process in Yb+ + Rb collisions is the radiative charge transfer, while in the case of Ca+ + Rb collisions nonadiabatic transitions due to spin-orbit coupling dominate. Theoretical results are in a good agreement with available experimental data.