REACTION-RATE OSCILLATION OF CO OXIDATION ON PT(210)

We report on the occurrence of kinetic instabilities and regular oscillations in the rate of CO2 formation as it results from the CO oxidation reaction carried out in ultrahigh vacuum and high vacuum on a platinum (210) surface. While the surface properties are characterized and controlled by combined low-energy electron diffraction, Auger electron spectroscopy, thermal desorption spectroscopy, and ΔΦ measurements, the rate of reaction is monitored by measurements of the partial pressures of the reactants and/or of the work-function change of the Pt(210) surface. We have followed the reaction kinetics as a function of "external" parameters (PCO, PO2, T) and have investigated the conditions under which oscillations occur. Likewise, the influence of some of the "internal" parameters (sample cleanliness, gas purity, surface structure) has been worked out. Finally, possible mechanisms for the occurrence of periodic oscillations are discussed, including the local oscillation as well as the process of synchronization. © 1990 American Institute of Physics.