Regensburg 2007 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 44: Poster Session II (Semiconductors; Oxides and Insulators: Adsorption, Clean Surfaces, Epitaxy and Growth; Surface Chemical Reactions and Heterogeneous Catalysis; Surface or Interface Magnetism; Solid-Liquid Interfaces; Organic, Polymeric, Biomolecular Films; Particles and Clusters; Methods: Atomic and Electronic Structure; Time-resolved Spectroscopies)

O 44.61: Poster

Mittwoch, 28. März 2007, 17:00–19:30, Poster C

Temperature dependent femtosecond two-photon photoemission from ultrathin MgO films — •Tobias Gleitsmann, Mihai E. Vaida, and Thorsten M. Bernhardt — Institut für Oberflächenchemie und Katalyse, Universität Ulm, 89069 Ulm, Germany

Due to their chemical and electronical properties, ultra-thin Magnesia films represent an ideal substrate system in order to investigate small deposited metal clusters. Especially the band gap of these isolating films in principle enables the observation of the cluster electronic states near the Fermi level independently from the substrate states whereas avoiding charging effects. The electronic structure of these ultra-thin magnesia films supported on a Mo(100) single crystal surface is investigated as a function of the post-deposition annealing temperature via femtosecond two photon photoemission spectroscopy and electron energy loss spectroscopy. Additionally, the film composition and crystal structure is analyzed by temperature programmed desorption mass spectrometry, Auger electron spectroscopy, and low energy electron diffraction, respectively. Strong evidence is found for the formation of an optical resonance at 4.6 eV with increasing annealing temperature accompanied by a change in the surface work function.