External noise in surface reactions

Stochastic fluctuations or noise in complex dynamical systems with strong
nonlinearities give rise to unexpected and new ordered phenomena. Chemical
reactions on solid surfaces exhibit non-linear behavior, such as
bistability, self-sustained kinetic oscillations, chaos and spatiotemporal
patterns. For this reason, understanding the influence of noise on the
complex behavior of catalytic surface reactions has become a challenge in
recent years. In this talk a theoretical study of external noise on two
minimalistic models for the catalytic CO oxidation on surface reactions
is presented. We show that those deterministic models present kinetic
bistability. We also show that in or near the region where bistability is
observed a time scale separation between the oxygen coverage and the CO
coverage exists. It allows a reduction of the models by the adiabatically
elimination of the fast oxygen coverage (quasi-steady state
approximation). Then, stochastic models are constructed by superposing
noise on the fraction of CO in the constant gas flow directed at the
surfaces. Reduced one variable stochastic models can also be found after
the adiabatic elimination of oxygen coverage. This reduction allows us to
analyze theoretically the interplay between external noise and the kinetic
bistability. Firstly, it is reported the phenomena of noise-induced shift
of steady states. Secondly, it is shown evidence for a transition to a
bistable state induced by noise. The analytical results are compared with
simulations of the original two variable stochastic reaction systems.