Stark widths and shifts for spectral lines of Sn IV

Abstract

In this paper, we present theoretical Stark widths and shifts calculated corresponding to 66 spectral lines of Sn IV. We use the Griem semi-empirical approach and the COWAN computer code. For the intermediate coupling calculations, the standard method of least-squares fitting from experimental energy levels was used. Data are presented for an electron density of 1017 cm−3 and temperatures T = 1.1-5.0 (104 K). The matrix elements used in these calculations have been determined from 34 configurations of Sn IV: 4d10 ns(n = 5-10), 4d10 nd(n = 5-8), 4d9 5s2, 4d9 5p2, 4d9 5s5d, 4d8 5s5p2 and 4d10 5g for even parity and 4d10 np(n = 5-8), 4d10 nf (n = 4-6), 4d9 5snp(n = 5-8), 4d8 5s25p and 4d9 5snf (n = 4-10) for odd parity. Also, in order to test the matrix elements used in our calculations, we present calculated values of radiative lifetimes of 14 levels of Sn IV. There is good agreement between our calculations and the experimental radiative lifetimes obtained from the bibliography. The spectral lines of Sn IV are observed in UV spectra of HD 149499 B obtained with the Far Ultraviolet Spectroscopic Explorer, the Goddard High Resolution Spectrograph and the International Ultraviolet Explorer. Theoretical trends of the Stark broadening parameter versus the temperature for relevant lines are presented. Also our values of Stark broadening parameters have been compared with the data available in the bibliography.