Statistical and Dynamical Aspects
of Surface Reactions:
Theory, Modelling and Experiments
July 3-5, 2000
Scientific Background
Recent experimental techniques have opened a new insight in the study of
mesoscopic
structures on reactive surfaces [1-3]. Transient effects associated with
local pattern formation have now
become accessible to direct experimental observation by applying scanning
tunneling microscopy (STM).
Field ion microscopy (FIM) is used to obtain nanoscale information on the
occurrence of kinetic
instabilities along with sustained oscillations, propagating waves and
explosive behavior. The analysis
and understanding of such nanoscale phenomena require the development of
new theoretical approaches using
the tools of the theory of non-linear dynamical systems, non-equilibrium
statistical physics and
stochastic processes, together with the development of new computational
techniques, at the microscopic and
mesoscopic level, using the tools of Monte-Carlo and molecular dynamics
techniques.
It is now well established that many local factors are influencing reactive
processes on catalytic surfaces
such as the limitations on the mobility of the adsorbed molecules and the
localization of the reactions.
Another limiting step is the collision mechanism between the surrounding
gas molecules and the active
sites on the crystal surface. Moreover the kinetic instabilites are often
associated with
adsorbate-induced surface restructuring. Attractive lateral interactions
between adsorbates play a
crucial role in pattern formation [4-6]. All these facts indicate an
intricate coupling between the
microscopic level and the collective behavior described by the macrovariables.
Theoretical investigations have proposed simple model systems that can be
viewed as paradigms for reactive
dynamics and anomalous transport on heterogeneous substrates. In
particular, anomalous (superdiffusive or
subdiffusive) transport on random surfaces, stratified porous media or
fractal surfaces has been shown to
affect not only the dynamics of the reactions but also the steady state
itself. Analytical methods used
for the study of these problems include exact configuration enumeration or
master equation approach which
can take into account local effects, inhomogeneous fluctuations, geometric
constraints and catalytic
surface anomalies [7-14].
In parallel, with the growth of fast computational techniques, an important
effort has been devoted to the
development of numerical treatments of heterogeneous catalysis related
problems. The numerical methods in
use today range from the microscopic level of quantum ab-initio
calculations to the mesoscopic Monte Carlo
[15-19] and molecular dynamics simulations [20] up to the macroscopic
mean-field level description [3].
Bridging the length and time scales of the different levels is a very
challenging problem to be addressed
in this meeting.
References
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