Atomic data for the S IV 10.5- m fine-structure transition

Abstract

New atomic data relevant to the fine-structure S IV transition at a wavelength of 10.5 μm are presented. The transition probability deduced from configuration interaction wavefunctions agrees with that obtained by Naqvi, but not with the recent result of Bhatia, Doschek & Feldman. Electron impact collision strengths for this transition have been calculated using the R-matrix method. They confirm the important resonance contribution found by Dufton et al. but lead to collision rates which are up to 15 per cent larger. The effect of these data on current models of H II regions is discussed and the authors suggest that the accuracy of such models may be limited by errors in the atomic data for many of the fine-structure lines involved.