Doubly-differential cross section calculations for $K$-shell vacancy production in lithium by fast O$^{8+}$ ion impact

TL;DR

This paper presents a theoretical study of inner-shell vacancy production in lithium caused by fast O$^{8+}$ ions, using a combined single-electron amplitude approach to accurately predict doubly-differential cross sections that align well with experimental data.

Contribution

The study introduces a multielectron theoretical method that improves predictions of vacancy production, highlighting the importance of two-electron processes over single-electron models.

Findings

Good agreement with experimental data for low electron energies

Two-electron excitation-ionization processes are crucial

Single-active-electron models are less accurate

Abstract

Inner-shell vacancy production for the O$^{8+}$-Li collision system at 1.5 MeV/amu is studied theoretically. The theory combines single-electron amplitudes for each electron in the system to extract multielectron information about the collision process. Doubly-differential cross sections obtained in this way are then compared with the recent experimental data by LaForge et al. [J. Phys. B 46, 031001 (2013)] yielding good resemblance, especially for low outgoing electron energy. A careful analysis of the processes that contribute to inner-shell vacancy production shows that the improvement of the results as compared to single-active-electron calculations can be attributed to the leading role of two-electron excitation-ionization processes.