Dirac R-matrix collision strengths and effective collision strengths for transitions of Ni xvii^⋆

School of Mathematics and Physics, The Queens University of Belfast, Belfast BT7 1NN, Northern Ireland, UK
e-mail: c.hudson@qub.ac.uk

Received: 1 September 2011
Accepted: 2 November 2011

Abstract

Context. Electron impact excitation collision strengths are required for the analysis and interpretation of stellar observations.

Aims. This calculation aims to provide fine structure effective collision strengths for the Ni xvii ion using a method which includes contributions from resonances.

Methods. A fully relativistic R-matrix calculation has been performed using the DARC code. In the structure part of our calculation 141 fine-structure levels are employed and 37 of these are used in the scattering calculation.

Results. Collision strengths have been determined for 666 fine-structure transitions arising from the 37 lowest j-levels involving configurations 3s², 3p², 3d², 3s3p, 3s3d, 3p3d and 3s4s. The effective collision strengths for these transitions have been calculated for electron temperatures (T_e) in the range log ₁₀T_e(K) = 4.5 − 8.0. Effective collision strengths are tabulated for transitions between the first ten fine structure levels, arising from the 3s², 3s3p and 3p² configurations. The remaining transitions are available at the CDS as well as via the author’s website.