Berlin 2012 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 54: Nanostructures at surfaces II

O 54.6: Vortrag

Mittwoch, 28. März 2012, 18:00–18:15, MA 042

Reactivity of Co-alloy clusters — •Ivan Baev, Torben Beeck, Michael Martins, and Wilfried Wurth — Universität Hamburg, Institut für Experimentalphysik

The chemical reactivity of small particles such as clusters strongly varies as a function of size in the Nano scale. Understanding the nature of chemical reactions at this small size limit is crucial for a further development of Nano catalysts. With our source "ICARUS" we can create a perfectly size selected cluster beam in the size range of 20 atoms per cluster. This beam is used to deposit clusters onto metallic substrates or thin oxide films. Clusters are deposited using the "soft-landing" technique to avoid fragmentation, agglomeration or implantation of the clusters into the substrate combined with a low surface coverage of less than 5% of a monolayer. Using core-level photoelectron spectroscopy at the BESSY U49-2PGM1 beamline the metallic core levels are measured as a function of cluster size and composition. The core level spectra are very sensitive to the chemical environment of the cluster so that chemical processes can be directly traced back to the cluster sites. Combined with the measurement of oxygen and carbon 1s core levels a stoichiometric interpretation of the surface reactions can be given. This work is supported by the DFG through the collaborative research center SFB 668.