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Theoretical cross sections for electron-impact ionization of the neutral W atom and W$^+$ ion are reported. The direct ionization cross sections were calculated by using the binary-encounter Bethe (BEB) model and the indirect ionization cross sections resulting from numerous excitation-autoionization (EA) were calculated by using scaled Born cross sections. Contributions to indirectionization from spin-forbidden and $\Δ n = 1$ excitations, where $n$ is the principal quantum number, are noticeable unlike in light atoms. The single ionization cross section of W$^+$ is increased by about 10$\%$ due to the indirect EA of $5p$ electrons in the range of the incident electron energies between $40$ and $60$ eV. In the case of neutral W the EA cross sections are very small for the $^7$S$_3$ level which is the first metastable term of W and because the excitations to the high spin states are mostly in
Citation
International Journal of Mass Spectrometry
Pub Type
Journals
Keywords
autoionization, ionization cross section, W, W+
Citation
Kwon, D.
, Rhee, Y.
and Kim, Y.
(2021),
Ionization of W and W+ by Electron Impact, International Journal of Mass Spectrometry
(Accessed October 10, 2025)