Dresden 2009 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 47: Methods: Scanning probe techniques II
O 47.6: Vortrag
Donnerstag, 26. März 2009, 11:45–12:00, SCH A316
Transport of product gases in a scanning mass spectrometer setup — •Matthias Roos1, Dan Zhang2, Joachim Bansmann1, Olaf Deutschmann2, and R. Jürgen Behm1 — 1Institute of Surface Chemistry and Catalysis, Ulm University, D-89069 Ulm — 2Institute for Chemical Technology and Polymer Chemistry, University of Karlsruhe, D-76131 Karlsruhe
The transport and distribution of reaction products above microstructured catalytically active samples was studied by spatially resolved scanning mass spectrometry and by combined Monte Carlo simulations and Fluid Dynamics calculations. For CO oxidation on planar Pt microstructures, the spatial distribution of CO2 product gas was probed via a thin quartz capillary, which leads the gases to a quadrupole mass spectrometer. To obtain reasonable lateral resolution, the capillary orifice was located a few micrometers above the sample surface during measurement. In this geometry, shadowing by the capillary results in a local reduction of the reactant partial pressures underneath the capillary. To quantitatively analyse the reaction rates, the threedimensional distribution of CO2 product gas was modeled, considering the flow of educt gases, and their local variation of the pressure and the gas temperature.