Heterogeneous Nucleation by Aggregates of Particles

Abstract

The induction of a new phase by fine particles of a nucleating substance is complicated not only by variation in sizes but also by aggregation. The general effect of aggregation is to decrease the total number of particles but to reduce the supercooling (or supersaturation) necessary for growth of a new phase. Point contacts appear to be more fruitful than do line contacts, although both may be able to cause a substance to be more active than a large flat surface of the substrate. If the contact between particles is not a specially favoured position for nucleation, the aerosol as a whole appears to contain a higher proportion of active particles because of the persistence of initially active particles and the loss of less active ones.