Kinetic phase transitions in a contaminated monomer-dimer reaction model
The irreversible kinetics of a monomer-dimer reaction on a catalyst surface [the Ziff-Gulari-Barshad (ZGB) model] in the presence of a contaminant species is studied by means of Monte Carlo simulation. The only processes allowed to the contaminant are adsorption and desorption; it is otherwise inert. The reaction window, delimited by a second order irreversible phase transition at low monomer concentration (lower bound transition) and by a first order one at high monomer concentration (upper bound transition) in the ZGB model is found to shrink with increasing contaminant concentration in a way that depends on its adsorption-desorption kinetics. Through epidemic analysis, it is also found that the upper bound transition changes from first to second order and that the lower bound transition can also be affected depending on the contaminant adsorption-desorption kinetics. The results may provide alternative explanations for experimental observations.
Bustos
V
Laboratorio de Ciencias de Superficies y Medios Porosos, Universidad Nacional de San Luis, Chacabuco 917, 5700 San Luis, Argentina.
Unac
RO
Zgrablich
G