On the Sn I and Sn II Stark broadening

The Stark widths (W) of 12 neutral and 16 singly ionized tin (Sn I and Sn II, respectively) spectral lines have been measured in a laboratory helium plasma at 13 000 K electron temperature and 5.1 x 1022 m-3 electron density. Many of them are the first data in the literature. At mentioned plasma conditions, the Stark broadening has been found to be the dominant mechanism in line shape formation. The modified version of the linear, low-pressure, pulsed arc was used as a plasma source operated in helium with tin atoms, as impurities, evaporated from tin cylindrical plates located in the homogeneous part of the discharge, providing conditions free of self-absorption. Our Sn II W values are compared to the recent theoretical data calculated on the basis of the modified semi-empirical approach and, also, to the existing experimental W values. Our normalized Stark widths are much smaller (up to a factor of 4, on average) than those measured in a laser-produced plasma and in a plasma created by the shock-wave tubes. An agreement, within the accuracy of the experiment and uncertainties of the used theoretical approach, with the recent calculated W data was found. Our normalized Sn I Stark widths are much smaller than those observed in the mentioned plasma sources