RHEED structure analysis of the oscillatory catalytic CO oxidation at Pt(110) surfaces

Autor(en): Tappe, W
Korte, U
MeyerEhmsen, G
Stichwörter: 1X2; carbon monoxide; CARBON-MONOXIDE; catalysis; Chemistry; Chemistry, Physical; DESORPTION; ENERGY ELECTRON-DIFFRACTION; KINETIC OSCILLATIONS; models of surface chemical reactions; models of surface kinetics; OXYGEN-ADSORPTION; PATTERN-FORMATION; PHASE-TRANSITIONS; Physics; Physics, Condensed Matter; platinum; RECONSTRUCTION; reflection high-energy electron diffraction; sticking; thermal desorption; TRANSFORMATION
Erscheinungsdatum: 1997
Volumen: 388
Ausgabe: 1-3
Startseite: 162
Seitenende: 176
The catalytic CO oxidation at Pt(110) is observed with RHEED. Due to differential pumping of the electron gun, rocking curves can be measured up to pressures in the 10(-3) mbar range. This allows, for the first time, structural investigations with atomic resolution under time-dependent reaction conditions. At very sharply defined values of CO and O pressures at 535 K, the intensities of the diffraction spots oscillate with a frequency of about 0.6 Hz. These oscillations are associated with a periodic lifting of the (1 x 2) missing-row phase into a disordered (1 x 1) phase, which takes place spatially homogeneously over the observed part of the surface. A multiple scattering scheme for RHEED intensity calculations is used to evaluate the rocking curves. The changes of the substrate structure and the variation of the coverages of several adsorption sites for CO and O are obtained. A simplified Version of differential rate equations allows the time-dependent sticking, desorption and reaction of the adsorbates during the oscillations to be visualized and yields estimates of the relevant rate constants. (C) 1997 Elsevier Science B.V.
ISSN: 00396028
DOI: 10.1016/S0039-6028(97)00393-2

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