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arXiv · 1302.6107

Storage Ring Cross Section Measurements for Electron Impact Single and Double Ionization of Fe^13+ and Single Ionization of Fe^16+ and Fe^17+

M. Hahn·A. Becker·D. Bernhardt·M. Grieser·C. Krantz·M. Lestinsky·A. Müller·O. Novotný·R. Repnow·S. Schippers·K. Spruck·A. Wolf·D. W. Savin
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Abstract

We report measurements of electron impact ionization (EII) for Fe^13+, Fe^16+, and Fe^17+ over collision energies from below threshold to above 3000 eV. The ions were recirculated using an ion storage ring. Data were collected after a sufficiently long time that essentially all the ions had relaxed radiatively to their ground state before data were collected. For single ionization of $\fethirteen$ we find that previous single pass experiments are more than 40% larger than our results. Compared to our work, the theoretical cross section recommended by Arnaud & Raymond (1992) is more than 30% larger, while that of Dere (2007) is about 20% greater. Much of the discrepancy with Dere (2007) is due to the theory overestimating the contribution of excitation-autoionization via n=2 excitations. Double ionization of Fe^13+ is dominated by direct ionization of an inner shell electron accompanied by autoionization of a second electron. Our results for single ionization of Fe^16+ and Fe^17+ agree with theoretical calculations to within the experimental uncertainties.

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M. Hahn, A. Becker, D. Bernhardt, M. Grieser, C. Krantz, M. Lestinsky, A. Müller, O. Novotný, R. Repnow, S. Schippers, K. Spruck, A. Wolf, D. W. Savin. 2013-02-25. Storage Ring Cross Section Measurements for Electron Impact Single and Double Ionization of Fe^13+ and Single Ionization of Fe^16+ and Fe^17+. https://doi.org/10.1088/0004-637x/767/1/47

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