Effective collision strengths for transitions in Ni XIX

Abstract

Aims. In this paper we report electron impact collision strengths and excitation rates for transitions among the lowest 89 levels of Ni xix.Methods. The Dirac atomic -matrix code (darc) is adopted for the calculations of collision strengths and subsequently the effective collision strengths.Results. Collision strengths for resonance transitions among 89 levels arising from the (1s) 2s2p, 2s2p3, 2s2p3, 2s2p4, and 2s2p4 configurations of Ni xix are reported over a wide energy range below 250 Ryd. Additionally, effective collision strengths for all 3916 transitions among the 89 levels are listed over a wide temperature range below 10 K. Comparisons are made among different calculations and the accuracy of the data is assessed. Finally, comparisons between theoretical and experimental intensity ratios of some prominent lines of Ni xix are discussed.. © 2008 ESO.