Atomic data from the IRON Project^*

LII. Electron excitation of Ni⁺²⁴

¹ Department of Applied Mathematics, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
² Department of Physics, University of Strathclyde, Glasgow G4 0NG, UK
³ Observatoire de la Côte d'Azur, Département Gian Domenico Cassini, BP 4229, 06304 Nice Cedex 4, France

Corresponding author: M. C. Chidichimo, mchidich@math.uwaterloo.ca

Received: 31 October 2002
Accepted: 28 January 2003

Abstract

This paper reports on the calculation of collision strengths for electron induced transitions in the beryllium-like ion Ni xxv whose ground state is . We make use of the R-matrix method in conjunction with the intermediate frame coupling transformation (IFCT). The target has 98 fine structure states corresponding to and . 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 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 is tabulated against for the 45 transitions linking the lowest 10 levels. We also give results for 5 transitions in the X-ray region which are needed in solar studies. The temperature range is centred on which is where this ion has its maximum coronal abundance.