Term-Dependent Hybridization of the5fWave Functions of Ba andBa++

Abstract

It is shown that, unlike in neutral Ba, the $4d\to 5f$ transitions cannot be neglected in the interpretation of the $4d$ spectrum of ${\mathrm{Ba}}^{++}$. A term-dependent hybridization of the $5f$ wave functions occurs, the effects of which reverse between Ba and ${\mathrm{Ba}}^{++}$, and oscillator strength reappears in the $4d\to \mathrm{nf}$ ($n>~5$) transitions. A second kind of wave-function collapse is identified and its effects are described.