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Iowa State University

1992

Biological and Chemical Physics

Articles 1 - 3 of 3

Full-Text Articles in Physics

Spatial Variation Of A Short-Lived Intermediate Chemical Species In A Couette Reactor, R. Dennis Vigil, Q. Ouyang, Harry L. Swinney Apr 1992

Spatial Variation Of A Short-Lived Intermediate Chemical Species In A Couette Reactor, R. Dennis Vigil, Q. Ouyang, Harry L. Swinney

R. Dennis Vigil

We have conducted experiments and simulations of the spatial variation of a short-lived intermediate species (triiodide) in the autocatalytic oxidation of arsenite by iodate in a reactor that is essentially one dimensional-the Couette reactor. (This reactor consists of two concentric cylinders with the inner one rotating and the outer one at rest; reagents are continuously fed and removed at each end in such a way that there is no net axial flux and there are opposing arsenite and iodate gradients.) The predictions ?f a one-dim~ns~onal . reaction-diffusion model which has no adjustable parameters, are In good qualItative (and, In ...


Kinetic Phase Diagrams For The Monomer–Dimer Surface Reaction: Unification Of Mean‐Field And Lattice–Gas Behavior, James W. Evans Jan 1992

Kinetic Phase Diagrams For The Monomer–Dimer Surface Reaction: Unification Of Mean‐Field And Lattice–Gas Behavior, James W. Evans

Physics and Astronomy Publications

We provide a unified discussion of kinetic phase transitions for mean‐field and lattice–gas treatments of the monomer–dimer surface reaction. For high surfacemobilities, kinetics is typically well described by mean‐field rate equations. These reveal bistability over a range of monomer adsorption rates which diminishes with increasing nonreactive monomer desorption rate d, and vanishes at some critical d=dc. Relative stability in the bistable region is determined from the behavior of chemical waves corresponding to the displacement of one stable state by the other. Their evolution is determined via appropriate reaction ...


Modeling Spatiotemporal Behavior Of The No+Co Reaction On Pt, James W. Evans, H. H. Madden, R. Imbihl Jan 1992

Modeling Spatiotemporal Behavior Of The No+Co Reaction On Pt, James W. Evans, H. H. Madden, R. Imbihl

Physics and Astronomy Publications

Various features of NO+CO reaction kinetics on Pt(100) surfaces, including temporal oscillations, are well described by a three‐variable model incorporating only the CO, NO, and O coverages. Here we analyze the corresponding reaction–diffusion equations demonstrating the existence of chemical waves where an ‘‘oscillating phase’’ displaces an unreactive NO/CO phase leaving a spatially periodic structure in its wake; pulses excited via inhomogeneities from an unreactive NO/CO background; and Turing structures for sufficiently unequal NO and CO diffusion rates.