Issue |
Astron. Astrophys. Suppl. Ser.
Volume 118, Number 1, July 1996
|
|
---|---|---|
Page(s) | 157 - 162 | |
DOI | https://doi.org/10.1051/aas:1996186 | |
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
Received:
17
October
1995
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