Angular Momentum Dependence of Autoionization Rates in Doubly Excited Rydberg States of Ba

The results of an experimental laser study of state-selected, doubly excited states $\mathrm{msnl}$ ($m=7-11\mathrm{}$, $n=13-20\mathrm{}$) in barium are reported. Measurements are made of the autoionization rates of the doubly excited states as a function of "core" size principal quantum number $m$. For $\mathrm{msnd}$ states, the autoionization rate increases rapidly with increasing $m$, while for $\mathrm{msns}$ states, the autoionization rate is independent of $m$. This difference in the dependence of the autoionization rate on $m$ is not predicted by calculations using an independent particle framework (e.g., frozen core Hartree-Fock).