Analysis of the 4p 64d 7-(4p 64d 64f + 4p 54d 8) transitions in the Sn VIII spectrum

The spectrum of the 4p 64d 7-(4p 64d 64f + 4p 54d 8) transitions in Sn VIII occurring in the wavelength range 140–170 Å and excited in a vacuum spark plasma was investigated. For the first time, 113 spectral lines of these transitions were classified and the energies of 38 levels of the 4d 64f and 4p 54d 8 configurations were experimentally determined. The semiempirical energy parameters determined by least-squares fitting of the experimental energies of Sn VIII are in good agreement with the parameters of the corresponding configurations obtained previously in the analysis of the Sn VI and Sn VII spectra.