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Astron. Astrophys. Suppl. Ser. 142, 313-316
Atomic data from the IRON Project
XLI. Electron excitation rates among the 3d2 fine-structure
levels of Ca-like Fe VII
K.A. Berrington1 - S. Nakazaki2 - P.H. Norrington3
1 - School of Science & Mathematics, Sheffield Hallam University,
Sheffield S1 1WB, UK
2 -
Department of Materials Science, Faculty of Engineering,
Miyazaki University, Miyazaki 889-21, Japan
3 -
Department of Applied Mathematics & Theoretical Physics,
Queen's University, Belfast BT7 1NN, UK
Received July 30; accepted October 22, 1999
Abstract:
Electron excitation collision strengths of 3d
2fine-structure transitions in Ca-like Fe
VII
are calculated using an R-matrix method,
which included the 80 terms arising from the
3d
2, 3d4s, 3d4p, 3d4d, 3d4f and 3p
53d
3 configurations.
Extensive autoionizing resonance structures together with
channel coupling is therefore explicitly included;
relativistic effects are accounted for by
a term-coupling
transformation.
A thermal average is taken to
obtain the effective fine-structure
collision strength as a function of electron temperature
T,
for log
T(K) = 4.3-6.
Open 3p-shell resonances are seen to considerably enhance the
background collision strength, by several factors for some of the
3d
transitions.
Key words: atomic data
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