The AES and EELS study of small rhodium clusters deposited onto alumina substrates

There is a continued interest in systematic studies of UHV grown supported metal clusters and small particles. One important goal of this research is progress in the understanding of the origin of the catalytic properties of small transition metal particles. For this it is necessary to understand the relationship between the atomic structure, the electronic structure and the reactivity of the particles. samples were prepared by depositing very small clusters of Rh onto polycrystalline γ-Al2O3, onto α-Al2O3(0 0 0 1) single crystal and onto a thin alumina film which were previously deposited onto a niobium polycrystalline foil (Al2O3/NbOX/Nb). The electronic structure of the alumina surfaces has been investigated. Energy loss spectroscopy has revealed features on clean Rh foil due to single and collective excitations of the conduc tion electrons. A new surface plasmon energy near 6.5 eV has been noticed in those clusters of rhodium deposited onto polycrystalline γ-Al2O3 and onto α-Al2O3(0 0 0 1) single crystal, different from the surface plasmon energy of a Rh foil (8 eV).