Effective Collision Strengths for Fine‐Structure Transitions from the 3s²3p⁵²PGround State of Chlorine–like Nixii

Abstract

The R-matrix method is used to compute electron impact collision strengths for transitions in Ni XII from its ground-state Ðne-structure levels. Sophisticated conÐguration-interaction wave functions are used to represent the 14 lowest L S target states employed in the R-matrix expansion. By transforming the L S-coupled reactance matrices, and by assuming a Maxwellian velocity distribution for the incident electrons, the e †ective collision strengths are calculated for the transition within 3s23p5 2P1@2 o È3s23p5 2P 3@2 o the ground state and from both these Ðne-structure levels to the 29 excited levels arising from states obtained from 3s3p6 and 3s23p43d conÐgurations. E †ective collision strengths, obtained in the temperature range log (K), are expected to have an accuracy of better than 20%. T e \ 3.2È6.6

EFFECTIVE COLLISION STRENGTHS FOR ELECTRON-IMPACT EXCITATION OF Ni XII

“…The electron-impact collision strengths were produced by utilizing the R matrix computer codes described by Berrington et al [11]. A description of both approximations is published elsewhere [12].It is useful, however, to give a summary of how the Ni XII ion was represented in the present calculation. Fourteen target states were included in the wave function expansion, namely, 3s 2 3p…”

CHIANTI – an atomic database for emission lines

“…Ni xii thermally-averaged collision strengths have been calculated by Matthews et al (1998) in the temperature range 10 3.2 − 10 6.6 K. The authors used the R-Matrix method. To our knowledge, these are the only largescale electron-ion collision calculations performed in the literature.…”