Dresden 2017 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 95: Metal Substrates: Adsorption of Atoms and Inorganic Molecules

O 95.1: Hauptvortrag

Donnerstag, 23. März 2017, 15:00–15:30, WIL A317

Visualizing surface X-ray diffraction: the active phase of CO oxidation model catalysts — •Johan Gustafson — Synchrotron Radiation Research, Lund University, Lund, Sweden

Surface X-Day Diffraction (SXRD) is a very powerful surface characterization tool, especially for in-situ investigations. As a diffraction tool, it is closely related to Low-Energy Electron Diffraction (LEED), but is much less used due to the need for intense synchrotrons and the complexity to record and interpret the diffraction data.

The use of large 2D detectors provide the means to facilitate both the collection and the interpretation of the data. As a larger part of reciprocal space is probed simultaneously, larger datasets can be aqcuired in realistic time frames, which enables a more comprehensible visualization of the data, similar to a LEED-pattern. In addition, significantly more information can be obtained from time-resolved measurements.

We have used SXRD with 2D detectors to establish the most active phase of Pd(100) and Rh(111) during catalytic CO oxidation, a subject that has been under debate for about 15 years. In contrast to what is often assumed, these model catalysts behave quite differently, and while the most active phase of rhodium is metallic, for Pd it is a thin oxide film. Some of the conclusions we draw would not have been possible without 2D detectors.