KINETICS OF A DIMER-DIMER IRREVERSIBLE CATALYTIC SURFACE-REACTION

The kinetics of irreversible dimer-dimer surface reactions of the type A(2)+B-2-->2AB with desorption of dimer B-2 has been investigated by means of Monte Carlo simulation. For a desorption probability (P) of B -2 equal to zero, a single discontinuous transition separating an A+va cancies saturated surface from a B+vacancies saturated surface is obta ined at y(B2) = 0.5 (y(B2) is the partial pressure of B-2 in the gas p hase). With the increase in P, a steady reactive state which is separa ted from the poisoned states by two continuous transitions is obtained for this system. The position of the transition points depends upon t he value of P. For P equal to one, a single continuous transition at y (B2)=0.538 separates a poisoned state from a steady reactive state. Th e window width, which defines the steady reactive state, shows an expo nential behavior with P. Preliminary studies have been under taken to determine the universality class of the system for different P values. (C) 1998 American Institute of Physics.