Double circular states of barium

We have populated the double circular Ba 4f5g levels using multistep laser excitation from the ground state. The observed autoionization rates of these levels are quite low, which may indicate strong electron correlations. We present a semiclassical picture that explains the long lifetimes of these states without quantum-mechanical correlation effects. In addition to the 4f5g states, we have also observed higher-lying 4fng states. In particular, we have observed the mixing of the bound 4f6g and 4f7g levels with the 6${\mathit{d}}_{\mathit{j}}$nf and 6${\mathit{d}}_{\mathit{j}}$nh series indicating direct orbital angular momentum exchange between the two valence electrons. We observe orbital angular momentum exchange between bound electrons in which the initial and final states of both electrons can be identified.