Berlin 2008 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 73: Symposium: Bimetallic Nanosystems: Tuning Physical and Chemical Properties II (Invited Speakers: André Fielicke, Thomas Risse, Jürgen Behm)

O 73.8: Vortrag

Donnerstag, 28. Februar 2008, 16:45–17:00, MA 005

Adsorption of CO on PdRu surfaces alloys studied by infrared reflection absorption spectroscopy — •Heinrich Hartmann, Thomas Diemant, Joachim Bansmann, and Rolf Jürgen Behm — Institute of Surface Chemistry and Catalysis, Ulm University, D-89069 Ulm

The adsorption of CO on PdRu surface alloys on Ru(0001) has been studied by IRAS. The surface alloys were created by evaporating Pd on a Ru(0001) substrate and subsequent annealing to 1100 K. STM imaging shows a tendency toward island formation (phase separation) of the two constituents. IRAS experiments were performed to determine the CO adsorption sites on these bimetallic alloys. CO shows the same tendency for occupation of adsorption sites on the mixed PdRu surface as on the pure Ru(0001) and Pd(111) surfaces. On the Ru parts of the alloys CO adsorbs in a linear on-top configuration, on the Pd parts the adsorption of CO takes place on threefold-hollow sites (at small CO coverages) and on linear and bridge sites at (higher CO coverages). For all absorption bands the C-O vibration shifts to lower frequencies compared to the pure Ru(0001) and Pd(111) surfaces. These shifts are attributed to a modification of the electronic properties of the system.