Berlin 2015 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 24: Catalysis: Structural Effects
O 24.3: Vortrag
Dienstag, 17. März 2015, 11:00–11:15, MA 144
Tuning Excitability by Alloying: The System Rh(111)/Ni/O2+H2 — •Tim Smolinsky, Mathias Homann, Florian Lovis, and Ronald Imbihl — Institut für Physikalische Chemie und Elektrochemie, Leibniz Universität Hannover, Germany
Catalytic oxidation of hydrogen on Rh(111) is a bistable system but through alloying with nickel the system becomes excitable [1]. Varying the nickel coverage from zero up to several monolayers we studied chemical wave patterns and asdorbate-induced Ni segregation in the 10−6 and 10−5 mbar range at temperatures between 323 K and 773 K with photo electron emission microscopy (PEEM). The surface was characterized with Auger Electron Spectroscopy (AES) and Low Energy Electron Diffraction (LEED). Already small Ni coverages lead to excitable behavior and at high Ni coverages 3D-NiO particles start to nucleate on the surface. Nickel is apparently highly mobile in the top layers of the crystal. Shape, velocity and wavelength of the pulses depend on the nickel coverage. A bifurcation diagram showing the dependence of the system behavior on the nickel coverage was constructed.
[1] F. Lovis, T. Smolinsky, A. Locatelli, M. Á. Niño and R. Imbihl, J. Phys. Chem. C 116 (2012) 4083-4090.