Hybridization of angular-momentum eigenstates in nonspherical sodium clusters

Angle-resolved photoelectron spectra of low-temperature sodium clusters Na-33(-) and Na-34(-) have been measured as a function of photon energy. The experiments in combination with density functional theory calculations demonstrate that despite the strongly oblate shape of the clusters, most of the occupied valence orbitals are close to angular-momentum eigenstates. Some states, however, exhibit a strongly mixed character. This mixing follows the selection rules Delta l = +/- 2 and Delta m = 0, which result from the approximate symmetry of the cluster deformation.