AVS 53rd International Symposium
    Surface Science Wednesday Sessions
       Session SS1-WeM

Paper SS1-WeM13
Fluctuation Effects in Nanoscale Surface Reaction Systems: Influence of Reactant Phase Separation during CO Oxidation

Wednesday, November 15, 2006, 12:00 pm, Room 2002

Session: Reactions on Metal & Bimetallic Surfaces
Presenter: D.-J. Liu, Ames Laboratory (USDOE)
Authors: D.-J. Liu, Ames Laboratory (USDOE)
J.W. Evans, Ames Laboratory (USDOE)
Correspondent: Click to Email
For catalytic surface reactions on supported metal nanoclusters@footnote 1@ or on the nanofacets of metal field-emitter tips,@footnote 2@ strong fluctuation effects can significantly impact behavior. A realistic atomistic multi-site lattice-gas model@footnote 3@ is used to assess such behavior in nanoscale CO-oxidation systems at lower temperatures (or higher pressures). Here, adspecies interactions and the availablity of various adsorption sites play an important role due to higher reactant adlayer coverages. Time-series for coverages and related quantities reveal fluctuation-induced transitions between distinct states associated with phase separation of reactant adspecies (in addition to transitions between stable reactive and inactive states associated with the Langmuir-Hinshelwood reaction mechanism). The former are plausibly observed in field-emission-micoscopy studies.@footnote 2@ We also characterize unusual features of hysteresis analyses in this regime, and assess the role played by defects in enhancing transitions. @FootnoteText@ @footnote 1@ V. Johanek et al., Science 304 (2004) 1639.@footnote 2@ Y. Suchorski et al., Phys. Rev. Lett. 82 (1999) 1907.@footnote 3@ D.-J. Liu and J.W. Evans, J. Chem. Phys. 124 (2006) 154705.