Interface propagation and nucleation phenomena for discontinuous poisoning transitions in surface-reaction models

Journal Article · Wed Nov 30 23:00:00 EST 1994 · Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics; (United States)

DOI:https://doi.org/10.1103/PhysRevE.50.4302· OSTI ID:6835841

Evans, J W; Ray, T R ^[1]

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1. Ames Laboratory and Department of Mathematics, Iowa State University, Ames, Iowa 50011 (United States)

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.

• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 6835841
• Journal Information: Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics; (United States), Journal Name: Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics; (United States) Vol. 50:6; ISSN PLEEE8; ISSN 1063-651X
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
DIFFUSION
FLUCTUATIONS
INTERFACES
KINETICS
NUCLEATION
OXIDATION
OXIDES
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
REACTION KINETICS
SURFACE PROPERTIES
SURFACE TENSION
VARIATIONS