Interatomic Coulombic Decay as a New Source of Low Energy Electrons in slow Ion-Dimer Collisions

TL;DR

This study demonstrates that interatomic Coulombic decay in slow ion-dimer collisions produces significant low-energy electron emission, revealing a new electron source relevant at low projectile charge states.

Contribution

It provides experimental evidence for interatomic Coulombic decay as a novel low-energy electron source in slow ion-dimer collisions, highlighting the role of inner shell single-electron capture.

Findings

Low-energy electrons are produced via interatomic Coulombic decay after single-electron capture.

This process dominates over Auger electron emission in the studied regime.

Inner shell single-electron capture is negligible for high charge state projectiles.

Abstract

We provide the experimental evidence that the single electron capture process in slow collisions between O$^{3+}$ ions and neon dimer targets leads to an unexpected production of low-energy electrons. This production results from the interatomic Coulombic decay process, subsequent to inner shell single electron capture from one site of the neon dimer. Although pure one-electron capture from inner shell is expected to be negligible in the low collision energy regime investigated here, the electron production due to this process overtakes by one order of magnitude the emission of Auger electrons by the scattered projectiles after double-electron capture. This feature is specific to low charge states of the projectile: similar studies with Xe$^{20+}$ and Ar$^{9+}$ projectiles show no evidence of inner shell single-electron capture. The dependence of the process on the projectile charge state is interpreted using simple calculations based on the classical over the barrier model.