R-matrix electron-impact excitation data for the Ne-like iso-electronic sequence ^*

Department of Physics, University of Strathclyde, Glasgow, G4 0NG, UK e-mail: guiyun.liang@strath.ac.uk

Received: 1 February 2010
Accepted: 7 May 2010

Abstract

We present results for the electron-impact excitation of all Ne-like ions from Na⁺ to Kr²⁶⁺ obtained using the intermediate-coupling frame transformation R-matrix approach. For each ion's calculation, the close-coupling expansion is taken to be the 113 LS terms (209 levels) belonging to the configurations [ 1s²] 2s²2p⁶, 2s²2p⁵{3, 4, 5}l, 2s2p⁶{3, 4, 5}l (l ∈ , , , , and ), and 2s²2p⁵{6, 7}l' (l' ∈ , , and ). An additional configuration interaction effect arising from configurations of 2s²2p⁴3l{3, 4, 5}l'' (l'' ∈ , , , and ) was included in the target expansion. A detailed comparison of the target structure has been made for six specific ions (Si⁴⁺, Ar⁸⁺, Ca¹⁰⁺, Fe¹⁶⁺, Ni¹⁸⁺, and Kr²⁶⁺) spanning the sequence to assess the accuracy for the entire sequence. Effective collision strengths (Υs) are presented at temperatures ranging from 2 × 10²(q+1)² K to 2 × 10⁶(q + 1)² K (where q is the residual charge of ions, i.e. Z – 10). Detailed comparisons for the Υs are made with the results of previous calculations for several ions, which span the sequence. Furthermore, we examine the iso-electronic trends of effective collision strengths as a function of temperature. The present results are the only R-matrix ones for the majority of the ions and the most extensive and complete data for modelling to-date.