KINETICS OF CLUSTER AGGREGATION IN COMPETITION WITH A CHEMICAL GROWTH REACTION

The kinetics of abundances and the distribution in size of clusters at a given time are obtained by numerical simulation in the case where a chemical growth competes with the coalescence of clusters originating from isolated monomers. To take into account the size dependence of cluster reactivity, it is assumed that the chemical reaction occurs only beyond a critical value n(c). The kinetics of the total cluster concentration are unchanged by addition of the reactant but the size distribution is suddenly perturbed for sizes beyond n,. The decay of the reactant, the kinetics of a cluster of a given nuclearity and the distribution of sizes at a given time depend on the relative values of the rates of coalescence and of growth due to the reactant. It is shown how the initial conditions control the kinetics and the amplitude or the time of the maximum cluster abundance. The case of an attack by a chemical reactant on clusters, restricted to low values of n, is also considered. The concentration kinetics (for all size clusters) display much lower amplitudes than for pure coalescence case. No parity effects are observed.