A classical model for multiple-electron capture in slow collisions of highly charged ions with atoms

TLDR

A new version of the classical over‑barrier model for multiple‑electron capture in slow collisions between ions and atoms is described. The model extends the classical over‑barrier approach by accounting for multiple electron‑exchange pathways and incorporating a velocity‑dependent minimum energy uncertainty to capture dynamic effects. Without adjustable parameters, the model predicts absolute multiple‑capture cross sections and energy‑gain spectra that agree well with experimental data.

Abstract

A new version of the classical over-barrier model for multiple-electron capture in slow collisions between ions and atoms is described. This version accounts for the different ways in which an exchange of a certain number of electrons can occur. Since no adaptable parameter is involved this model has predictive power. Model predictions of absolute multiple capture cross sections are compared with experiment and are found to be in good agreement. Some dynamic effects are accounted for by introducing a velocity-dependent minimum energy uncertainty. Predicted widths of energy gain spectra and of the spectra of autoionisation electrons are found to be in reasonable agreement with experiment.