Hyperfine structure of the 4f85d6s2 configuration of the Tb atom

In this work, A and B hyperfine structure constants of electronic levels belonging to the configuration 4f85d6s2 of the terbium atom are presented, obtained via investigation of the hyperfine structure of 42 spectral lines, performed with the method of laser-induced fluorescence (LIF) in a hollow cathode discharge. Results for 14 of the investigated levels belonging to the configuration 4f85d6s2 were obtained for the first time. Also results concerning the hyperfine structure of 29 levels, involved in the transitions as upper levels, are presented. For these levels, almost all the results were obtained for the first time. On the basis of the results obtained within this work and those known from the literature, parametrization of the hyperfine structure was performed. The determined values of one-electron parameters for configuration 4f85d6s2 were compared to the values known from literature, determined so far on the basis of a much lower number of electronic levels. Values of relativistic radial integrals of the hyperfine structure for electrons 4f and 5d of the configuration 4f85d6s2 were calculated with the use of the MCDF code. The comparison of radial integrals calculated semi-empirically with those determined with MCDF method yielded an estimate of the values of configuration interaction parameters in the case of both magnetic dipole and electric quadrupole interactions of the terbium atom.