IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Surface Science Thursday Sessions
       Session SS1-ThP

Paper SS1-ThP3
Lateral Interactions in Elementary Surface Reactions between CO and NO on Rhodium Surfaces

Thursday, November 1, 2001, 5:30 pm, Room 134/135

Session: Catalysis on Model Systems Poster Session
Presenter: J.W. Niemantsverdriet, Eindhoven University of Technology, The Netherlands
Authors: M.J.P. Hopstaken, Eindhoven University of Technology, The Netherlands
A.P. van Bavel, Eindhoven University of Technology, The Netherlands
J.W. Niemantsverdriet, Eindhoven University of Technology, The Netherlands
Correspondent: Click to Email
Unraveling catalytic mechanisms in terms of elementary reactions and determining the kinetic parameters of such steps is at the heart of understanding catalytic reactions at the molecular level. Here we report the use of temperature programmed desorption and static secondary ion mass spectrometry to study reactions between NO and CO on Rh(100) and (111). On both surfaces the reaction rates of the different elementary steps depend highly on coverage. At low coverage, dissociation of NO is completed around 250 K and 340 K for the Rh(100) and the Rh(111) surface, respectively. When the surface is saturated with NO, dissociation only starts when some NO desorbs first, i.e. when empty sites become available. However, inhibition of NO dissociation at intermediate coverages cannot be explained by site blocking alone, but is due to lateral interactions with other adsorbates such as N, O, and NO. Studying the effect of coadsorption of these species enables an estimate of the magnitude of these lateral interactions. The combined influence of lateral interactions and site blocking leads to explosive behavior in the CO + NO reaction on saturated surfaces. The explosion is triggered by the desorption of a small amount of CO. The liberated sites enable the dissociation of NO and the subsequent reaction of O-atoms with CO creates even more free sites. The process is autocatalytic in the free sites and becomes explosive. These explosions have been observed in real time with TPD and SIMS.