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 msnl (m=7-11, n=13-20) 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 msnd states, the autoionization rate increases rapidly with increasing m, while for 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).