SELF-ACCELERATING KINETICS OF CO2 FORMATION ON IR(110)

We report measurements of CO oxidation by CO molecular beam titration measurements on an Ir(110) surface precovered with atomically bonded o xygen. During the course of the titration, both the reaction product C O2 and the backscattered CO intensity were detected. The oxygen precov erage, the kinetic energy of the molecular CO and the surface temperat ure were varied. The CO2 formation rate increases with increasing CO e xposure time and depends strongly on surface temperature. The self-acc elerating CO2 formation kinetics are semi-quantitatively discussed usi ng computer simulations with rate equations of the Langmuir-Hinshelwoo d type with coverage-dependent reaction rate coefficients and adsorpti on probabilities. (C) 1998 Elsevier Science B.V.