Theoretical study of electron-impact broadening for highly charged Ar XV ion lines

Spectral line widths produced by collisions between charged particles and emitters are of special interest for precise plasma spectroscopy. The highly charged Ar XV ion is demonstrated to have strong intrashell electron interactions, which manifest as an atomic system with many resonance structures, due to the quasi-degeneracy of orbital energies. In this paper we use the relativistic R-matrix method to investigate the electron-impact broadening of highly charged Ar XV ion spectral lines under the impact approximation. It is found that the results considering resonance structures are significantly different from those of the distorted wave approach. Furthermore, we propose a new empirical formula with a correction term to take into account the effect of resonances for electron-impact widths over a relatively wide range of plasma conditions. The corresponding fitting parameters of the new empirical formula for all 47 calculated transitions are also given with an estimated accuracy within 1%, which should be convenient for practical applications. The dataset that supported the findings of this study is available in Science Data Bank, with the link https://doi.org/10.57760/sciencedb.j00113.00101.

Automated summary

In this study, the relativistic R-matrix method is used to investigate the electron-impact broadening of spectral lines produced by highly charged Ar XV ions. The results considering resonance structures differ significantly from the distorted wave approach. A new empirical formula with a correction term is proposed to account for the effect of resonances in a relatively wide range of plasma conditions. The fitting parameters for all 47 calculated transitions are provided, with an estimated accuracy within 1%.