EDP Sciences
Free access
Issue
A&A
Volume 446, Number 1, January IV 2006
Page(s) 361 - 366
Section Atomic, molecular and nuclear data
DOI http://dx.doi.org/10.1051/0004-6361:20053631


A&A 446, 361-366 (2006)
DOI: 10.1051/0004-6361:20053631

Atomic data from the IRON project

LX. Electron-impact excitation of n = 3, 4 levels of Fe $^{\mathsf{17+}}$
M. C. Witthoeft1, N. R. Badnell1, G. Del Zanna2, K. A. Berrington3 and J. C. Pelan4

1  Department of Physics, University of Strathclyde, Glasgow, G4 0NG, UK
    e-mail: witthoeft@phys.strath.ac.uk
2  MSSL, University College London, Holmbury St., Mary Dorking, RH5 6NT, UK
3  School of Science and Mathematics, Sheffield Hallam University, Sheffield, S1 1WB, UK
4  Gatsby Computational Neuroscience Unit, University College, 17 Queen Square, London, WC1N 3AR, UK

(Received 14 June 2005 / Accepted 1 September 2005)

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 2s2 2p5, 2s 2p6, 2s2 2p4 3l, 2s 2p5 3l, and 2p6 3l configurations while the second calculation includes the 2s2 2p4 4l, 2s 2p5 4l, and 2p6 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 2s2 2p4 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.


Key words: atomic data -- atomic processes




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