Campus Units

Physics and Astronomy, Mathematics, Ames Laboratory

Document Type

Article

Publication Version

Published Version

Publication Date

1994

Journal or Book Title

Physical Review E

Volume

50

Issue

6

First Page

4302

Last Page

4316

DOI

10.1103/PhysRevE.50.4302

Abstract

Here, we consider discontinuous nonequilibrium phase transitions to poisoned or ‘‘adsorbing’’ states in lattice-gas models of surface reactions. Specifically, we examine the monomer or CO-poisoning transition in the Ziff-Gulari-Barshad monomer-dimer reaction model for CO oxidation, modified to include adspecies diffusion. For CO pressures below the poisoning transition, we first characterize the propagation of and fluctuations at an interface between reactive and CO-poisoned states. Here, we utilize ideas from spatial contact models, reaction-diffusion theory, and kinetic roughening theory. Evolution is described by the Kardar-Parisi-Zhang equation, but with the nonlinearity and kinetic surface tension vanishing on approaching the transition. Next, again for CO pressures below the transition, we consider the evolution of a ‘‘nucleus’’ of the reactive state embedded in the CO-poisoned state, now exploiting concepts from epidemic theory. We elucidate the divergence and ‘‘sharpening’’ of the critical size of this nucleus, both approaching the transition and with increasing adspecies diffusion rates. The deviation from mean-field divergence approaching the transition is related to the vanishing of the kinetic surface tension. The sharpening is related to the reduced influence of fluctuations. Throughout this contribution, we focus on providing a unifying framework that can describe both the fluctuation-dominated behavior of the lattice-gas model for low adspecies diffusion rates, and the crossover to the deterministic mean-field behavior for high diffusion rates where the adlayer is well mixed or randomized.

Comments

This article is published as Evans, J. W., and T. R. Ray. "Interface propagation and nucleation phenomena for discontinuous poisoning transitions in surface-reaction models." Physical Review E 50, no. 6 (1994): 4302, doi:10.1103/PhysRevE.50.4302. Posted with permission.

Copyright Owner

American Physical Society

Language

en

File Format

application/pdf

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