Rydberg atom-ion collisions in cold environments

In this work, we investigate the parameter space associated with different plausible approaches for the dynamics of Rydberg-ion collisions as a collision energy function. As a result, we find that at the lowest reachable temperatures in ultracold systems, a classical treatment is appropriate to study such systems' dynamics. In particular, we have developed a quasi-classical trajectory approach to study charge exchange and l-mixing collisions for Li^*-Li⁺ and Li^*-Cs⁺ at collision energies down to 1K. For cold collisions, we find the charge exchange cross section deviating from the n⁴ geometric scaling. Furthermore, we find both an influence of the ionic core-repulsion and variations for two different models used for describing the electron-core potential for low-energy collisions.