Astron. Astrophys. Suppl. Ser.
Volume 118, Number 1, July 1996
|Page(s)||157 - 162|
|Published online||15 July 1996|
Atomic data from the IRON Project. XV. Electron excitation of the fine-structure transitions in hydrogen-like ions He ii and Fe xxvi
Department of Applied Mathematics & Theoretical Physics, The Queen's University, Belfast, BT7 1NN, UK
Send offprint request to: K.A. Berrington
Accepted: 6 November 1995
Electron excitation collision strengths for fine-structure transitions involving relativistic levels with principal quantum number in hydrogen-like ions He ii and Fe xxvi are calculated using R-matrix techniques. The model target ion includes all 25 energy levels with . Low-energy collision strengths dominated by autoionizing resonances are averaged over a Maxwellian velocity distribution to obtain effective collision strengths as a function of electron temperature. In the case of He ii, such resonances enhance the collision strength by up to a factor of 3 over earlier calculations for excitation of the levels due to the presence of doubly-excited states near the thresholds. For He ii, the data are presented at four temperature points ranging from log(K) to 4.3, and for Fe xxvi from log(K) to 7.5.
Key words: atomic data
© European Southern Observatory (ESO), 1996