Stark broadening parameters in the S III spectrum

Abstract

Stark widths and shifts of astrophysically important 10 doubly ionized sulfur (S III) spectral lines (within the 3d-4p and 4s-4p transitions) have been measured in a S F6 plasma created in the linear, low-pressure, pulsed arc discharge at about 35000 K electron temperature and about 2.8 × 1023 m-3 electron density. The widths and shifts have been calculated using the semiclassical perturbation formalism (SCPF) (taking into account the impurity of energy levels, i.e. that the atomic energy levels are expressed as a mix of different configurations due to the configuration interaction), modified semiempirical (SEM) approximation, simplified semiclassical theory (G) and its modification (GM) taking into account new energy level values. Calculations have been performed for electron temperatures between 10 000 K and 150 000 K for electrons, protons and helium ions as perturbers. The measured and calculated S III shifts present the first published data in this field.