Isolated Core Excitation Of High-Orbital-Quantum-Number Rydberg States Of Ytterbium

We study isolated core excitation of ultracold ytterbium Rydberg atoms of high orbital angular momentum quantum number l. Measurements were performed on the 6s(1/2)40l -> 6p(1/2)40l transition with l = 5-9. The extracted energy shifts and autoionization rates are in good agreement with a model based on independent electrons, taking interactions into account in a perturbative approach. We reveal a slow decrease in the autoionization rates with l, explained by the strong coupling of the 6p(1/2)nl autoionizing state with the 5d(3/2)epsilon l' continua compared to previously studied divalent atoms.