On the role of interatomic Coulombic decay in slow collisions of singly and doubly charged helium ions with neon dimers

We revisit previous model calculation for He²⁺-Ne₂ collisions¹ and extend the analysis of electron removal processes which result in dimer fragmentation. Specifically, instead of a standard independent-electron multinomial evaluation of single- and many-electron transitions we use a Slater-determinant-based method to account for the Pauli principle, and we take into account that the projectile changes its charge state when capturing an electron from the first atom of the dimer it encounters (assuming parallel orientation of the dimer with respect to the projectile beam axis). We confirm the previous prediction that interatomic Coulombic decay (ICD) is a strong channel at low collision energies. For singly-charged projectiles (He⁺ ions) we find that the total ICD cross section is smaller than for He²⁺ impact, but that there is no substantial competing process in the Ne⁺ - Ne⁺ fragmentation channel. We conclude that if one were to measure the kinetic energy release spectrum one would find a clean signature of ICD in it.

¹ T. Kirchner, J. Phys. B 54, 205201 (2021)