Low-energy collisions of Rydberg atom-ion systems are investigated theoretically. We present the parameter space associated with suitable approaches for the dynamics of Rydberg atom-ion collisions, i.e., quantum, Langevin, and classical exchange regimes, showing that for the lowest reachable temperatures a classical treatment is appropriate. A quasiclassical trajectory method is used to study charge exchange cross sections for ${\mathrm{Li}}^{*}\text{−}{\mathrm{Li}}^{+}$ and ${\mathrm{Li}}^{*}\text{−}{\mathrm{Cs}}^{+}$ at collision energies down to $1\mathrm{K}$. For cold collisions we find the charge exchange cross section deviating from the $n^4$ geometric scaling. Furthermore, for low-energy collisions, we find both an influence of the ionic core repulsion as well as variations for two different models used for describing the electron-core potential.

• Received 31 December 2020
• Accepted 29 March 2021

DOI:https://doi.org/10.1103/PhysRevA.103.043323

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Published by the American Physical Society