Berlin 2008 – scientific programme

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O: Fachverband Oberflächenphysik

O 86: Oxides and Insulators: Adsorption

O 86.6: Talk

Friday, February 29, 2008, 10:45–11:00, MA 141

Single adatom adsorption on SiO2 thin films — •Stefan Ulrich, Niklas Nilius, and Hans-Joachim Freund — Fritz-Haber-Institut, Berlin, Germany

The contribution discusses the unusual adsorption characteristic of a thin SiO2 film grown on Mo(112), which strongly depends on the geometric size of the adsorbates. The SiO2 layer consists of a network of -Si-O- hexagons exposing nano-pores with 3-4 Angstrom diameter. As revealed from low-temperature STM measurements, Pd adatoms penetrate this opening with nearly no barrier and bind strongly to the Mo-SiO2 interface. Au atoms on the other hand are too big and adsorb only at line defects in the oxide surface, where larger pores are exposed. The electronic properties of the adatoms and their interaction with the SiO2 support are deduced from tunneling spectroscopy.