A KINETIC TREATMENT OF HETEROGENEOUS NUCLEATION

An expression is derived for the rate of evaporation of a molecule interacting with a spherical cap cluster and the solid on which the cluster is located. The motion of the evaporating molecule in the potential well generated by its interaction with the cluster and substrate is described by a diffusion equation in the energy space. The rate of heterogeneous nucleation, calculated in the steady-state approximation, is strongly dependent on the interactions with the solid substrate. A comparison between the kinetic and classical theories shows that the former provides much larger values than the latter for small critical clusters (large supersaturations) but tends to the latter for large critical clusters.