Electron-impact single ionisation of W14+ ions: Subconfiguration-average and level-to-level distorted wave calculations

TL;DR

This study compares two theoretical approaches for calculating electron-impact ionisation cross sections of W14+ ions, finding that a hybrid method aligns well with experimental data near the ionisation threshold.

Contribution

It introduces a hybrid SCADW and LLDW approach for more accurate ionisation cross section calculations of W14+ ions, especially near the threshold.

Findings

Hybrid approach agrees with experimental data near threshold.

Pure SCADW calculations deviate significantly from experiments.

The 4d->5d excitation-autoionisation channels are critical for accurate results.

Abstract

The cross section for electron-impact single ionisation of W14+ ions has been calculated by using two different approaches, i.e., the subconfiguration averaged distorted-wave (SCADW) method and the more involved level-to-level distorted-wave (LLDW) method. Both methods are found to yield very similar results except for the 4d->5d excitation-autoionisation (EA) channels that straddles the ionisation threshold. Accordingly, a hybrid theoretical cross section where the $4d\to 5d$ EA SCADW cross section is replaced by its LLDW counterpart is in good agreement with the experimental result from an electron-ion crossed-beams experiment. This is in contrast to pure SCADW calculations for W14+ and neighbouring charge states which exhibit significant deviations from the experimental near-threshold cross sections of Schury et al. [J. Phys. B 53 (2020) 015201].