Energy levels, wavelengths and radiative rates for transitions in Hg-like Bismuth

The fourth spectrum of bismuth (Bi IV) has been investigated in the vacuum ultraviolet region. Recordings of bismuth spectra were made on a 3-m normal incidence vacuum spectrograph at Antigonish laboratory in Canada using a triggered spark light source. The theoretical interpretation for this spectrum was made with the pseudo-relativistic Hartree-Fock approach implemented in Cowan's code. The previous analysis of the energy level structure of Bi IV is confirmed and extended with the identifications of the 6p(2 1)S(0) and 5d(9)6s(2)6p D-3(2) levels, which were not reported earlier. Two new doubly excited configurations 6p6d and 6p7s were studied for the first time with the identification of 56 spectral lines. In total, 84 energy levels were located in the 5d(10)[6s(2)+ 6snp (n = 6, 7) + 6p(2) + 6snd (n = 6, 7) + 6s5f], 6p6d, 6p7s, 5d(9)6s(2)np (n = 6-10) and 5d(9)6s(2)nf (n = 5-13) configurations, among which fifteen were newly established. A total of 552 spectral lines have now been classified in Bi IV in the region 193-5000 angstrom. We also present the optimized energy level values, transition rates and Ritz wavelengths along with their uncertainties evaluated using the least-squares fitting procedure. (c) 2022 Elsevier Ltd. All rights reserved.