Inequivalent models of irreversible dimer filling: Transition state'' dependence
- Department of Chemistry, Eastern Michigan University, Ypsilanti, MI (USA)
- Ames Laboratory, Ames IA (USA) Department of Physics, Iowa State Univ., Ames, IA (USA) Department of Mathematics, Iowa State Univ., Ames, IA (USA)
Irreversible adsorption of diatomics on crystalline surfaces is sometimes modeled as random dimer filling of adjacent pairs of sites on a lattice. We note that this process can be implemented in two distinct ways: (i) randomly pick adjacent pairs of sites, {ital jj}{prime}, and fill {ital jj}{prime} only if both are empty (horizontal transition state); or (ii) randomly pick a single site, {ital j}, and if {ital j} and at least one neighbor are empty, then fill {ital j} and a randomly chosen empty neighbor (vertical transition state). Here it is instructive to consider processes which also include competitive random monomer filling of single sites. We find that although saturation (partial) coverages differ little between the models for pure dimer filling, there is a significant difference for comparable monomer and dimer filling rates. We present exact results for saturation coverage behavior for a linear lattice, and estimates for a square lattice. Ramifications for simple models of CO oxidation on surfaces are indicated.
- DOE Contract Number:
- W-7405-ENG-82
- OSTI ID:
- 5995450
- Journal Information:
- Journal of Chemical Physics; (USA), Vol. 93:11; ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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