Photoelectron spectroscopy of Cun- clusters : comparison with jellium model predictions

We present a comparison of the electronic level structure of Cu - n clusters with the jellium model using photoelectron spectroscopy of metal cluster anions. The spectra are recorded at an energy resolution of 30 meV using photon energies of up to 6.4 eV. We obtain a well resolved picture of the electronic structure of the 4s derived electronic states in the energy region between the localized 3d derived states and the highest occupied molecular orbital. The observed features can be assigned to the 1s, 1p, and 1d shells predicted by the jellium model if ellipsoidal distortions and effects like shake-up processes, multiplet splittings and the s–d hybridization are taken into consideration