Berlin 2008 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 18: Poster Session I - MA 141/144 (Atomic Wires; Size-Selected Clusters; Nanostructures; Metal Substrates: Clean Surfaces+Adsorption of Organic / Bio Molecules+Solid-Liquid Interfaces+Adsorption of O and/or H; Surface or Interface Magnetism; Oxides and Insulators: Clean Surfaces)
O 18.8: Poster
Montag, 25. Februar 2008, 18:30–19:30, Poster F
Metastable Impact Electron Spectroscopy (MIES) of intermediate nanocatalytic states — •Christopher Harding, Vahideh Habibpour, Sebastian Kunz, and Ulrich Heiz — Lehrstuhl für Physikalische Chemie, Technische Universität München,
Metastable ion electron spectroscopy (MIES) is a well established spectroscopic technique that can be applied in a new and novel way to nanocatalysts. It has several interesting benefits which include a dramatically enhanced sensitivity to electron orbitals with low ℓ-values (compared with UPS) and very low collision velocities leaving the surface virtually untouched.
Thin oxide films and mass-selected metal clusters form the basis of nanocatalysts and are thus of primary importance. In the MIES spectra high sensitivity to sub-1%ML coverages of clusters and also a strong enhancement of various spectral regions which give information on intermediate states in oxidation reactions can be seen.
According to theoretical predictions cluster-oxides intermediates are formed and play an important role in the catalysis of the CO oxidation reaction. These important and interesting predictions are made, based on size selected Pd clusters on MgO films. Using a laser vaporisation cluster source size selected clusters of Pd9 and Pd30 were deposited onto MgO films and this mechanism investigated. The experimental MIES studies confirm the intermediate oxide formation and illustrates other intriguing aspects of the Pd-oxide intermediate state.