Atomic data from the IRON project - LVI : Electron excitation of Be-like Fe XXIII for the n=2,3,4 configurations

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Chidichimo, M.C. and Del Zanna, G. and Mason, H.E. and Badnell, N.R. and Tully, J.A. and Berrington, K.A. (2005) Atomic data from the IRON project - LVI : Electron excitation of Be-like Fe XXIII for the n=2,3,4 configurations. Experimental Astronomy, 430 (1). pp. 331-341. ISSN 0922-6435 (https://doi.org/10.1051/0004-6361:20041358)

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Abstract

Collision strengths for electron induced transitions in the beryllium-like ion Fe+22 are calculated using the intermediate coupling frame transformation (ICFT) version of the R-matrix programs. Our target has 98 fine structure states 1 s(2) nl n'l' S LJ corresponding to n = 2 and n' = 2, 3, 4. The present calculation is for electron impact energies in the range 3.15 to 380 Ry. When T exceeds about ten million degrees one needs to take account of contributions to the thermally averaged collision strength Y coming from electrons with energies in excess of 380 Ry. We discuss a way of allowing for these contributions. Values of Y for all the transitions between the ground state and the excited states 1s(2) 2l n l n'l' S' L' J', with n' = 2, 3,4 are tabulated as a function of log T. The temperature range 6.3 less than or equal to log T less than or equal to 8.1 is centred on log T = 7.1 which is approximately where Fe+22 has maximum abundance in ionization equilibrium. To the best of our knowledge these are the first R-matrix calculations for Fe+22 for excitations to the n = 3, 4 levels. Good agreement with previous distored-wave calculations is found. However, the resonance contributions have an important effect on the effective collision strengths and in turn on the level populations.

ORCID iDs

Chidichimo, M.C., Del Zanna, G., Mason, H.E., Badnell, N.R. ORCID logoORCID: https://orcid.org/0000-0001-7418-7996, Tully, J.A. and Berrington, K.A.;
  • Item type:Article
    ID code:31189
    Dates:
    Date
    Event
    January 2005
    Published
    Subjects:Science > Physics
    Department:Faculty of Science > Physics
    Depositing user: Pure Administrator
    Date deposited:13 Jul 2011 08:55
    Last modified:11 Nov 2024 09:45
    URI:https://strathprints.strath.ac.uk/id/eprint/31189
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