ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
Using Monte Carlo simulations and both quasichemical (for nearest neighbors) and mean field (for next-nearest neighbors) approximations, we explore a kinetic lattice gas model to investigate recombinative thermal desorption. A previously introduced Monte Carlo algorithm, which correctly relates Monte Carlo simulation time and real time, is extended in order to quantify the kinetics and energetics of recombinative thermal desorption spectra. We consider the effects of lateral interactions between adsorbates, lattice geometry, and limited mobility of the adsorbate (nonequilibrium) on the temperature programmed desorption spectra. Furthermore, we analyze the apparent coverage dependence of both the activation energy and the preexponential factor of the desorption rate coefficient for both repulsive and attractive nearest-neighbor interactions on a square lattice. For a repulsive nearest-neighbor interaction, we find that kinetic compensation occurs for a surface coverage less than 0.6. However, for surface coverages greater than 0.6, we find that the activation energy and preexponential factor do not vary sympathetically. For an attractive nearest-neighbor interaction, kinetic compensation is only observed at high coverage. We elucidate the compensation effect quantitatively by considering the configurational distribution of adsorbates. © 1995 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.469449
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