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E. Napetschnig:
"Thin alumina films on NiAl(110): Structure, domain boundaries and nucleation and growth of metallic clusters";
Vortrag: Seminar Institut für Allgemeine Physik (IAP), TU Wien; 09.01.2007.

The properties and structure of small metal particles deposited on oxide surfaces attract much interest due to their applications in catalysis. Thin alumina films grown on NiAl(110) with transition metal clusters have proved to be a suitable model system for studies on heterogeneous catalysis. Oxidation of the (110) surface of NiAl at elevated temperatures leads to the formation of an alumina film of uniform thickness and structure. The alumina film grows on the NiAl(110) substrate in two reflection domains and exhibits a network of domain boundaries. The determination of the atomic arrangement of the oxide film and of the structure of the straight antiphase domain boundary was possible by combining atomically resolved STM (scanning tunneling microscopy) images and density-functional theory calculations. The domain boundaries act as nucleation centres for metal clusters and are therefore important when studying the growth mechanism of metal clusters.
In our study we have investigated the structure of Co, Pd and mixed Co-Pd clusters grown on the thin alumina film on NiAl(110) by STM, AES (Auger electron spectroscopy) and LEIS (low energy ion scattering). We have focused on the morphology of the Co and Pd clusters deposition at different temperatures and the morphological changes of clusters deposited at room temperature upon annealing to 300 °C. Besides we investigated the surface composition and morphology of bimetallic Co-Pd clusters at room temperature.