Regensburg 2016 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 64: Oxides and Interfaces: Adsorption II
O 64.3: Vortrag
Mittwoch, 9. März 2016, 15:30–15:45, H6
Copper deposition on stoichiometric and reduced ceria films — •Boris Groß and Niklas Nilius — Carl-von-Ossietzky Universität Oldenburg, Institut für Physik, D-26111 Oldenburg, Germany
Nearly stoichiometric and oxygen-deficient CeO2−x(111) films, grown on Ru(0001), have been titrated with Cu nanoparticles in order to explore the interaction of noble metals with reducible oxides. In contrast to Ag and Au that preferentially bind along oxide step edges, Cu randomly nucleates even on mildly reduced ceria, as revealed from low-temperature STM measurements. The observed nucleation behavior indicates a considerable Cu interaction with O vacancies in the surface. Moreover, a distinct bimodal size distribution is revealed for the Cu particles, with the mean size substantially varying on adjacent and even on single oxide terraces. As recorded particle sizes display a strong dependence on the STM bias voltage used for imaging, an electronic origin for the bimodal size distribution is anticipated. We discuss self-limiting Cu growth as a result of charge-transfer from underlying Ce3+ ions as well as a variable O vacancy concentration in differently thick ceria patches as possible reasons for the observed effect.