The effect of resonances on the forbidden line of He-like ions
- 1 January 1984
- journal article
- Published by IOP Publishing in Journal of Physics B: Atomic and Molecular Physics
- Vol. 17 (1), 73-81
- https://doi.org/10.1088/0022-3700/17/1/013
Abstract
Effective collision strengths are presented for the forbidden line 1s2 1S0-1s2s 3S1 in He-like ions taking account of the effect of resonances and their radiative decay. Results are obtained using the quantum defect theory developed by Gailitis (1963) and Seaton (1969) and are applied to the ions O VII, Mg XI, Ca XIX and Fe XXV. Excitation rates are given in LSJ coupling for a temperature range where these ions are abundant and they are compared, where possible, with previous results. The results indicate that the contribution of the resonances to the direct collision strength is lower than 20% for the temperature range of interest.Keywords
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