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 SS3-ThP

Paper SS3-ThP2
Simulation of Lateral Interactions in the Dissociation of NO on Rh(100) by Dynamic Monte Carlo Simulations

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

Session: Surface Reactions Poster Session
Presenter: A.P. van Bavel, Eindhoven University of Technology, The Netherlands
Authors: A.P. van Bavel, Eindhoven University of Technology, The Netherlands
J.J. Lukkien, Eindhoven University of Technology, The Netherlands
J.W. Niemantsverdriet, Eindhoven University of Technology, The Netherlands
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The kinetics of the dissociation of NO on Rh(100) is largely determined by lateral interactions as a recent study using Temperature Programmed Desorption (TPD) and Temperature Programmed Static Secondary Ion Mass Spectrometry (TPSSIMS) by Hopstaken et.al.@footnote 1@ clearly shows. At zero coverage limit the NO dissociation is completed around 200 K. At increasing initial NO coverages the dissociation is retarded due to strong repulsions between NO and its decomposition products. At saturation coverage the NO dissociation is even fully retarded until a few NO molecules desorb from the surface, thereby creating the necessary vacancies for dissociation. The created vacancies are immediately filled with the atoms formed. This way an auto-catalytic process is developed, since the atoms cause more stronger repulsions and thereby more desorption. Due to the essential role of interactions and to the possibility of island formation, the kinetics cannot satisfactorily be described using a mean-field approach. Therefore, we have developed a model to describe the dissociation of NO on Rh(100) by means of Dynamic Monte Carlo simulations. We have included pairwise additive interactions between neighbouring species and diffusion of all adsorbates. Repulsion between NO and its decomposition products is larger than the mutual repulsion between NO molecules. This - in combination with the higher mobility of NO - leads to segregation in the adlayer to form mixed N@sub ads@+O@sub ads@ islands and compression of the NO in islands. The Monte Carlo simulations provide a means to estimate the magnitude of the interaction between neighbouring adsorbate species. @FootnoteText@ @footnote 1@ Hopstaken, M.J.P., Niemantsverdriet, J.W.; J. Phys. Chem. 104 (2000) 3058.