Calculations of Dielectronic Recombination and Electron-impact Excitation Rate Coefficients of Highly Charged Sulfur Ions

Abstract

Connected to the experiment performed at the Stockholm electron beam ion trap, a systematic relativistic configuration-interaction calculation is carried out to compare with the experimental spectra. In particular, separate rate coefficients are calculated for dominant recombination and excitation processes in the range of the impact electron energy determined by the experiment. By means of the relevant experimental parameters, the presently calculated dielectronic recombination rate coefficients for and S14+ ions and electron-impact excitation ones for S15+, S14+, and S13+ ions are employed further to synthesize overall theoretical spectra for comparison with the experimentally measured spectra. Overall, very good agreements with the experimental results are found except for one missing excitation peak around the impact electron energy 2.52 keV, which cannot be explained by the present calculations and thus remains open.

Electron-impact recombination and excitation rates for charge-state-selected highly charged Si ions

“…In fact, this method has been used by our group in measurements of DR and EIE for highly charged sulfur ions [18]. A recent publication of a theoretical approach to DR and calculations of EIE for S showed very good agreement [19] with these S data [18].…”

Excitation and recombination studies with silicon and sulphur ions at an EBIT

“…In figure 6 we compare the experimental results for all DR channels of S 15+ and S 14+ ions with the by FAC calculated [17] and folded DR rate coefficients up to ∆n = 2 (red lines). The DR processes associated with the excitation of a K-shell electron to the L shell give rise to a series of strong peaks as labeled by the standard DR notations KLL, KLM, KLN, and KLO.…”

“…The calculated EIE rate coefficient by the FAC [17] is shown in figure 5 inset graph by the solid red line and the direct non-resonant part of it by the black dashed line. And, the overall photon rate coefficients (solid red line in figure 7) are obtained from FAC [12] by summing the charge state separate DR and EIE rate coefficients weighted by S 15+ , S 14+ , and S 13+ ion fractions that were determined in the experiment.…”

“…These compare reasonably well with corresponding experimental results [14] as shown in absolute scale in figure 7 (considering the statistical as well as systematic uncertainty of 20% 7. Experimental photon rate coefficients (grey area) compared with DR and EIE rate coefficients for S (13−15)+ ions calculated by FAC [17]. Adapted from [17].…”

“…Experimental photon rate coefficients (grey area) compared with DR and EIE rate coefficients for S (13−15)+ ions calculated by FAC [17]. Adapted from [17]. © 2020.…”