The first measured Mn II and Mn III Stark broadening parameters

Abstract

The shapes and shifts of the astrophysically interesting 11 singly and 3 doubly ionized manganese (Mn II and Mn III, respectively) spectral lines have been obtained in the laboratory helium plasma at a 49,000K electron temperature and 1.3×1023m−3 electron density. At mentioned plasma conditions, the Stark broadening has been found as the dominant mechanism in the line shape and shift formation. Our measured Stark widths (W) and shifts (d) are the first experimental data in Mn II and Mn III spectra and many of them represent the first published Mn II and Mn III Stark broadening parameters. Manganese atoms, as impurities in the driving gas, have been introduced by erosion from the manganese bands fixed on the discharge electrodes providing conditions free of self-absorption. Our W and d values are compared with the single calculated data set in the case of two Mn II multiplets, only. An agreement was found in the case of the Stark shift sign. Our measured W values are much higher than the calculated ones. At the above mentioned helium plasma conditions, the line splitting in a hyperfine structure has been overpowered by Stark and Doppler broadenings in the case of the Mn II lines belonging to the 3d54sa5S2–3d54pz5P1,2,3o transition (293.3055, 293.9308 and 294.9205nm). We estimate that at electron densities below 1021m−3 and electron temperatures below 8000K the components in the hyperfine structure can play an important role in the mentioned Mn II line shape formation.