Electron-impact excitation rates of Na-like ions

Abstract

Abstract. Electron excitation collision strengths for all the transitions among 3s, 3p, 3d, 4s, 4p, 4d, 4f states of the five Na-like ions Al III, Si IV, S VI, Ar VIII and Ca X are calculated in the R-matrix approximation. Eleven target terms are included in the expansion of the total wavefunction. These collision strengths are averaged over a Maxwellian velocity distribution to obtain effective collision strengths as a function of electron temperature. The resulting values are compared with the results of previous less elaborate calculations to find some disagreements.

Fine structure effective collision strengths for the electron impact excitation of Al III

“…Tabulations of the non-zero effective collision strengths for transitions between both the LS states and the fine structure levels are given for electron temperatures (T e ) in the range log 10 T e (K) = 3.6−5.6. Comparisons are made with previous calculations and we find good agreement with the work of Kimura et al (1998). …”

“…We find that there are discrepancies between the data from these three calculations, which is noted for example by Kimura et al (1998). The current work aims to resolve the discrepancies between the existing data and provide a set of effective collision strengths that can be confidently applied.…”

“…We also tabulate the energy levels calculated by Kimura et al (1998) and those of Dufton & Kingston (1987). For each of the calculations we display the energy levels and note the difference of these from the observed values of NIST in parentheses.…”

“…Theoretically, a number of calculations have been carried out in LS -coupling to determine the effective collision strengths for the Al  transitions. In this paper we compare with 3 previous calculations, carried out by Kimura et al (1998), Dufton & Kingston (1987) and Mitroy & Norcross (1989). Kimura et al (1998) performed an 11-state R-matrix calculation using the 11 lowest-lying levels as their target states, and using only real orbitals in their wavefunction expansions.…”

“…In this paper we compare with 3 previous calculations, carried out by Kimura et al (1998), Dufton & Kingston (1987) and Mitroy & Norcross (1989). Kimura et al (1998) performed an 11-state R-matrix calculation using the 11 lowest-lying levels as their target states, and using only real orbitals in their wavefunction expansions. The authors included 30 continuum orbitals and calculated the R-matrix radius to be 27.8 au, and considered partial waves for L = 0−10.…”