Photoelectron-Spectroscopy of Silver Clusters

A comparison of x-ray photoemission from Ag clusters deposited on polygraphite and highly oriented pyrolitic graphite shows the influence of the support both on the valence band and on the core 3 d level of the metal. Positive shifts have been obtained with respect to the bulk for the Fermi edge and the 3 d peaks depending on the number of silver atoms deposited on the substrates. When the deposition is very small (cluster regime) the positive shifts of the binding energies are quite different for different substrates and cannot have a common origin. In contrast with recent work, we show that several effects contribute to these shifts: initial state effects like charge redistribution as well as final state effects like the hole-electron interaction.