Berlin 2012 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 35: Poster Session II (Polymeric biomolecular films; Nanostructures; Electronic structure; Spin-orbit interaction; Phase transitions; Surface chemical reactions; Heterogeneous catalysis; Particles and clusters; Surface magnetism; Electron and spin dynamics; Surface dynamics; Methods; Electronic structure theory; Functional molecules)

O 35.63: Poster

Dienstag, 27. März 2012, 18:15–21:45, Poster B

Catalytic activity of supported Pt clusters compared to Pt(111) — •Andrew S. Crampton, Claron. J. Ridge, Florian F. Schweinberger, and Ulrich Heiz — Technische Universität München, Catalysis Research Center, Chair of Physical Chemistry, Lichtenbergstr. 4, 85748 Garching, Germany.

Softlanding size-selected metal clusters, generated with a laser ablation source and mass selected with a QMS, onto a metal oxide support enables independent size and coverage control. These model systems then provide a direct path for the experimental chemist to probe electronic and geometric effects by changing the particle size by one single atom. The reactivity of these systems is investigated using a variety of surface science methods such as TPD/TPR, pMBRS, IRRAS, UPS and MIES. Recent studies on adsorbates have proven the potential of MIES to study adsorbate systems with a superior sensitivity compared to UPS. With these methods the kinetics and thermodynamics of reactions on clusters can be examined, as well as the electronic structure and vibrational properties of the adsorbates. Of particular interest are common model systems and demanding reactions, such as hydrogenation of olefins, on Pt clusters in the range from a single atom to nano crystallites (1-80 atoms). Comparing the results of measurements on the clusters with Pt(111) within the same experimental setup allows for a precise and comprehensive understanding of the effects on catalytic activity imparted by particle masses in the non-scalable size regime. The information obtained from these experiments contributes to deciphering fundamental catalytic mechanisms on the nanoscale.