KINETICS OF CLUSTER AGGREGATION IN COMPETITION WITH A CHEMICAL GROWTHREACTION

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 c luster reactivity, it is assumed that the chemical reaction occurs onl y beyond a critical value n(c). The kinetics of the total cluster conc entration are unchanged by addition of the reactant but the size distr ibution is suddenly perturbed for sizes beyond n,. The decay of the re actant, the kinetics of a cluster of a given nuclearity and the distri bution of sizes at a given time depend on the relative values of the r ates 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 chem ical reactant on clusters, restricted to low values of n, is also cons idered. The concentration kinetics (for all size clusters) display muc h lower amplitudes than for pure coalescence case. No parity effects a re observed.