Volume 430, Number 1, January IV 2005
|Page(s)||331 - 341|
|Section||Atomic, molecular, and nuclear data|
|Published online||12 January 2005|
Atomic data from the IRON Project*
LVI. Electron excitation of Be-like Fe XXIII for the n = 2, 3, 4 configurations
Department of Applied Mathematics and Theoretical Physics, The Centre for Mathematical Sciences, Wilberforce Road, Cambridge CB3 OWA, Cambridge, UK e-mail: G.Del-Zanna@damtp.cam.ac.uk
2 Department of Physics, University of Strathclyde, Glasgow G4 0NG, UK
3 Département Cassiopée, Observatoire de la Côte d'Azur, BP 4229, 06304 Nice Cedex 4, France
4 School of Science and Mathematics, Sheffield Hallam University, Sheffield S1 1WB, UK
Accepted: 10 August 2004
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 corresponding to and . 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 coming from electrons with energies in excess of 380 Ry. We discuss a way of allowing for these contributions. Values of for all the transitions between the ground state and the excited states , with are tabulated as a function of . The temperature range is centred on 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 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.
Key words: atomic data / Sun: corona
Full Tables 2, 4 and 6 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (22.214.171.124) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/430/331. The full datasets of wavelengths and gf values (Table 4) and of effective collision strengths (Table 7) are only available at the same address. The same data are also available at the TIPbase (http://vizier.u-strasbg.fr/tipbase/home.html) database and as an `adf04' file at the Oak Ridge National Laboratory's database via http://www-cfadc.phy.ornl.gov/
© ESO, 2005
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