Atomic data from the IRON project LX : Electron-impact excitation of n=3, 4 levels of Fe17+

Witthoeft, M.C. and Badnell, N.R. and Del Zanna, G. and Berrington, K.A. and Pelan, J.C. (2006) Atomic data from the IRON project LX : Electron-impact excitation of n=3, 4 levels of Fe17+. Experimental Astronomy, 446 (1). pp. 361-366. ISSN 0922-6435

Abstract

We present results for electron-impact excitation of F-like Fe calculated using R-matrix theory where an intermediate-coupling frame transformation (ICFT) is used to obtain level-resolved collision strengths. Two such calculations are performed, the first expands the target using 2s(2) 2p(5), 2s 2p(6), 2s2 2p(4)3l, 2s 2p(5)3l, and 2p(6)3l configurations while the second calculation includes the 2s(2) 2p(4)4l, 2s 2p(5)4l, and 2p(6)4l configurations as well. The effect of the additional structure in the latter calculation on the n = 3 resonances is explored and compared with previous calculations. We find strong resonant enhancement of the effective collision strengths to the 2s(2) 2p(4) 3s levels. A comparison with a Chandra X-ray observation of Capella shows that the n = 4 R-matrix calculation leads to good agreement with observation.

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