Initial and final state effects in photoemission from Au nanoclusters on TiO2(1 1 0)

Valence level and shallow core states of Au nanoclusters on TiO2(1 1 0) have been studied by synchrotron excited photoemission. The shift to high binding energy and broadening of the Au 4f peaks with decreasing Au surface coverage can be understood in terms of decreasing cluster size and the associated effects of charge on the cluster in the final state. Shifts in the photoemission onset are much more pronounced than the core level shifts and show a strong dependence on the degree of reduction of the TiO2(1 1 0) substrate. These observations suggest that the photoemission onset is influenced by an initial state effect involving charge transfer from defect states into cluster states.