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O: Fachverband Oberflächenphysik
O 69: Symposium: Size-Selected Clusters at Surfaces III
O 69.3: Vortrag
Donnerstag, 28. Februar 2008, 14:30–14:45, MA 042
X-ray photoelectron spectroscopy on deposited nobel metal clusters — •Matthias Neeb, Baris Balkaya, Nicoletta Ferretti, and Wolfgang Eberhardt — BESSY, Albert-Einstein Str. 15, 12489 Berlin
Noble metal clusters (Cu, Ag, Au) were produced in a magnetron sputter source and mass-selected by a magnetic sector field prior to soft-landing on a p-doped Si-wafer. XPS, XANES, UPS and Auger spectra of the supported metal clusters at a surface coverage of ∼ 1 % have been measured with soft X-ray synchrotron radiation. The cluster spectra are compared with the respective bulk spectra of an evaporated metal film. In general, the core binding energies of the clusters vary with size and are blue shifted with respect to the bulk value. Similarly, the L3 absorption edge of Cu-clusters up to 70 atoms is blue shifted with respect to Cu-bulk. For larger Cu-clusters (≥ 13) a multiple-scattering NEXAFS-feature is detected behind the L3 absorption edge, indicating an icosahedral structure. The Auger energy of the clusters shows a red shift with respect to the bulk value. Moreover, the kinetic energy of the Auger electron is influenced by post-collison interaction (PCI) and varies with cluster size.