Atomic data from the IRON Project. LII. Electron excitation of Ni^{+24}
Abstract
This paper reports on the calculation of collision strengths for electron induced transitions in the berylliumlike ion Ni XXV whose ground state is 1s^{2} 2s^{2} ^{1}S_{0}. We make use of the Rmatrix method in conjunction with the intermediate frame coupling transformation (IFCT). The target has 98 fine structure states 1s^{2} nl n'l' SLJ corresponding to n = 2 and n' = 2, 3, 4 . Our calculation extends up to 440 Ry with respect to the ground state. In order to obtain reliable rate coefficients at high temperatures (T above 2 x 10^{7} K) we have extended our collision strengths to much higher energies by using a variety of techniques, including use of Burgess's interactive code OmeUps. The effective collision strength Upsilon is tabulated against log T for the 45 transitions linking the lowest 10 levels. We also give results for 5 transitions in the Xray region which are needed in solar studies. The temperature range 6.3 <=log T <=8.3 is centred on log T = 7.1 which is where this ion has its maximum coronal abundance.
Figures 1 to 8, and Appendix A are only available in electronic form at http://www.edpsciences.org
 Publication:

Astronomy and Astrophysics
 Pub Date:
 April 2003
 DOI:
 10.1051/00046361:20030131
 Bibcode:
 2003A&A...401.1177C
 Keywords:

 atomic data