Regensburg 2010 – scientific programme

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O: Fachverband Oberflächenphysik

O 11: Methods: Scanning probe techniques II

O 11.5: Talk

Monday, March 22, 2010, 16:00–16:15, H32

Structure and Charge State Characterization of Line Defects in the Alumina Film on NiAl(110) by Dynamic Force Microscopy — •Leonid Lichtenstein, Lars Heinke, Georg Hermann Simon, Thomas König, Markus Heyde, and Hans-Joachim Freund — Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14196 Berlin, Germany

Metal oxides play a decisive role in many technological applications such as microelectronics and heterogeneous catalysis. To understand their catalytic performance in detail, it is important to determine the atomic and electronic structure of their surfaces. For this purpose, the thin aluminum oxide film grown on NiAl(110) often serves as model system in catalysis. It has been shown that line defects like step edges and antiphase domain boundaries (APDB) are particularly active sites for, e.g., the decomposition of NO [1]. In this context, frequency modulated dynamic force microscopy (FM-DFM) and scanning tunneling microscopy (STM) are applied to unveil the atomic structure of the thin film and its line defects in ultra high vacuum at 5 K [2]. By means of bias spectroscopy [3] differences in the density of electronic states between domains and line defects were determined. The contact-potential spectroscopy shows different local work functions indicating different charge states for both. This study links catalytic processes to the electronic structure of line defects.

[1] S. Schauermann et al., Chem. Phys. Lett. 381 (2003) 298-305

[2] G. H. Simon et al., New J. Phys. 11 (2009), 093009

[3] N. Nilius et al., Phys. Rev. B 69 (2004), 121401