Core-polarization corrected Dirac-Fock computations of one-electron spectra in the rubidium isoelectronic sequence: Mo VI through Pb XLVI

Abstract

Core-polarization corrected Dirac-Fock computations were performed, under assumption of so-called one-electron spectrum over-imposed on multi-electron spectrum, to predict levels and oscillator strengths for lowest transitions of so far mostly unknown highly ionized spectra of the rubidium isoelectronic series from Tc VII through Pb XLVI. To evaluate the accuracy of our predictions, calculations were also made for Mo VI spectrum, where experimental and other theoretical data are available. Behavior of oscillator strengths along the isoelectronic sequence was studied, exhibiting some relativistic features for highly ionized systems. The effect of collapse of the 4p64f5/2,7/2 levels along the sequence leads to change in the level ordering between Rh IX (Z = 45) and Sn XIV (Z = 50) spectra. We also carefully monitored the influence of core polarization (CP) on both energy levels and oscillator strengths. For energy levels, the CP contributions are small and quickly diminish along the isoelectronic sequence. For oscillator strengths the CP influence is much more profound not only near the neutral end of the sequence but also for highly ionized spectra. Moreover, the relative CP contribution to oscillator strengths of the 4f5/2,7/2−5d3/2,5/2 transitions reaches extreme values in the vicinity of the collapse region, where the 4f5/2,7/2 levels fall below the 5d3/2,5/2 ones. Finally, the assumption of the so-called one-electron spectrum, i.e., arising from excitation of a single valence electron outside of the closed-shell core seems to be justified for all states in the spectra under consideration with exception of the 4f5/2,7/2 levels, which are heavily mixed with other states along the sequence.