Bistability and explosive transients in surface reactions: the role of fluctuations
and spatial correlations |
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Authors: | Y De Decker and F Baras |
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Institution: | (1) Department of Physics and Astronomy, University of California, 92617 Irvine, CA, USA;(2) Department of Mathematics, University of California, 92617 Irvine, CA, USA;(3) Department of Computer Science, University of California, 92617 Irvine, CA, USA;(4) Center for Complex Biological Systems, University of California, 92617 Irvine, CA, USA;(5) Institute for Genomics and Bioinformatics, University of California, 92617 Irvine, CA, USA |
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Abstract: | We study the dynamics of a class of catalytic surface
reactions in which an adsorbed molecule undergoes dissociation giving oxygen,
which then rapidly reacts with H adatoms to give water.
The reaction-diffusion equations predict bistability and explosive
transients similar to those observed in several low-pressure experiments.
Kinetic Monte Carlo simulations reveal however that the
dynamics can be strongly affected by spontaneous, inhomogeneous
fluctuations of composition on the surface. In particular,
bifurcation points can be displaced and the explosive character
of the transients can be lost, depending on a subtle balance between
the rate of reaction and the mobility of the decomposing species.
These effects can be quantified on the basis of
a stochastic formulation of the dynamics taking into account
spatial correlations.
This approach allows to better delimit
the applicability of the traditional
reaction-diffusion modelling in the case of reactions such as
the reduction of NO
x
or SO
x
species on catalytic surfaces. |
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Keywords: | |
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