Electron-impact single ionization of ${\mathrm{Fe}}^{3+}$ from the ground and metastable states

Electron-impact single ionization of ${Fe}^{3 +}$ from the ground and metastable states

Aušra Kynienė, Sigitas Kučas, Saulius Pakalka, Šarūnas Masys, and Valdas Jonauskas

Phys. Rev. A 100, 052705 – Published 18 November 2019

Abstract

Single ionization by electron impact of the ${Fe}^{3 +}$ ion is investigated using the Dirac-Fock-Slater approximation for the levels of the ground and first-excited $3 d^{4} 4 s$ configuration. Contributions from direct ionization (DI) and excitation-autoionization (EA) processes are taken into account. The scaled distorted-wave (DW) cross sections for DI and excitation by electron impact are used to analyze the experimental data. The study demonstrates the importance of correlation effects for the EA process. Good agreement with experimental data reveals that currently available DW cross sections and, therefore, the corresponding Maxwellian rate coefficients for electron-impact ionization process in ${Fe}^{3 +}$ are overestimated and their usage may lead to wrong predictions for charge state distribution in plasma.