Electron-impact ionization of Fe 8

Electron-impact ionization cross sections and Maxwellian rate coefficients are presented for the Fe 8+ ion by considering processes from the ground and metastable levels. The lifetimes of the levels for the 3s 2 3p 5 3d configuration were analysed using the extended basis of interacting configuratio...

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Bibliographic Details
Published in:Astronomy and astrophysics (Berlin) 2019-04, Vol.624, p.A14
Main Authors: Kynienė, Aušra, Kučas, Sigitas, Masys, Šarūnas, Jonauskas, Valdas
Format: Article
Language:English
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Summary:Electron-impact ionization cross sections and Maxwellian rate coefficients are presented for the Fe 8+ ion by considering processes from the ground and metastable levels. The lifetimes of the levels for the 3s 2 3p 5 3d configuration were analysed using the extended basis of interacting configurations. Convergence of the cross sections for the indirect process due to excitations to the high- n l subshells was investigated. We demonstrate that excitations to the subshells with orbital quantum number l  = 3 with subsequent autoionization dominate up to electron energies of ∼700 eV for the ground and metastable levels. Modelling of theoretical cross sections obtained for the ground and metastable levels to produce the best fit to the measurements shows that 15% of ions reach the reaction zone in the metastable state. The obtained results contradict the previous work that showed ∼30% for the metastable fraction.
ISSN:0004-6361
1432-0746
DOI:10.1051/0004-6361/201833762