Indication of strong interatomic Coulombic decay in slow He$^{2+}$-Ne$_2$ collisions

TL;DR

This study investigates electron removal and interatomic Coulombic decay in slow He$^{2+}$-Ne$_2$ collisions, confirming the dominance of ICD at low energies and highlighting its role in low-energy electron emission and dimer fragmentation.

Contribution

It provides the first detailed theoretical analysis of ICD in slow He$^{2+}$-Ne$_2$ collisions, emphasizing its significance over direct electron emission at low impact energies.

Findings

ICD is the dominant fragmentation process below 10 keV/amu.

The calculations confirm experimental results at 150 keV/amu.

Strong low-energy electron yield is expected in this regime.

Abstract

Electron removal in collisions of alpha particles with neon dimers is studied using an independent-atom-independent-electron model based on the semiclassical approximation of heavy-particle collision physics. The dimer is assumed to be frozen at its equilibrium bond length and collision events for the two ion-atom subsystems are combined in an impact parameter by impact parameter fashion for three mutually perpendicular orientations. Both frozen atomic target and dynamic response model calculations are carried out using the coupled-channel two-center basis generator method. We pay particular attention to inner-valence Ne($2s$) electron removal, which is associated with interatomic Coulombic decay (ICD), resulting in low-energy electron emission and dimer fragmentation. Our calculations confirm a previous experimental result at 150 keV/amu impact energy regarding the relative strength of ICD compared to direct electron emission. They further indicate that ICD is the dominant Ne$^+$ + Ne$^+$ fragmentation process below 10 keV/amu, suggesting that a strong low-energy electron yield will be observed in the ion-dimer system in a regime in which the creation of continuum electrons is a rare event in the ion-atom problem.