RELATIVISTIC CALCULATIONS OF THE FINE-STRUCTURE INTERVALS OF THE NS(2)NP(2)P TERMS AND THE IONIZATION ENERGIES OF THE CA-, SR- AND BA- IONS

We report new calculations of the energy differences between the ns(1/ 2)(2)np(1/2) and ns(1/2)(2)np(3/2) levels of the Ca-, Sr- and Ba- ions ; here n = 4, 5 and 6 for Ca-, Sr- and Ba-, respectively. The electron affinities of Ca, Pa and Sr have also been calculated. All estimates were obtained by performing a series of multiconfiguration Dirac-Fock calculations for the neutral atoms and their anions. Correlations amon g valence electrons in both the ground and excited states were include d in these calculations. Our estimate of the fine structure of the gro und stare of Sr- is in good agreement with recent measurements. Our es timates of the electron affinities of Ca, Sr and Ba are in reasonable agreement with experiment.