Regensburg 2013 – scientific programme

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O: Fachverband Oberflächenphysik

O 45: Metal Substrates II

O 45.2: Talk

Wednesday, March 13, 2013, 10:45–11:00, H42

Bimetallic PtAg/Pt(111) surfaces and their interaction with CO — •Thomas Diemant, Joachim Bansmann, and R. Jürgen Behm — Institute of Surface Chemistry and Catalysis, Ulm University, D-89069 Ulm, Germany

The growth of Ag films on a Pt(111) substrate at room temperature and the formation of PtAg/Pt(111) surface alloys by annealing to higher temperature (up to 900 K) was studied by a combination of X-ray photoelectron spectroscopy (XPS) and temperature-programmed desorption (TPD) measurements. XPS measurements indicate a modification of the electronic properties of both components in the bimetallic surface layer; most prominently the binding energy of the Ag peaks shifts compared to pure Ag.

In the next step, the interaction of CO with structurally well-defined PtAg/Pt(111) surface alloys was studied by TPD and high resolution electron energy loss spectroscopy (HREELS). These alloys were formed by annealing to 900 K; their structural properties had already been clarified before by scanning tunnelling microscopy (STM) measurements in our institute. Both on the low as well as on the high temperature side of the platinum related CO TPD peak additional features arise after alloy formation. Furthermore, a peak related to CO adsorption on Ag sites is detected at 150 K in the CO TPD spectra.