Self-consistent cluster approach to the homogeneous kinetic nucleation theory.

Abstract

An alternative, self-consistent formulation of the homogeneous nucleation theory has been proposed. This approach differs from the classical Becker-Doring-Zeldovich theory in two respects: (i) evaporation rates are evaluated by referring to the stable equilibrium of a saturated vapor rather than to the constrained metastable equilibrium of a supersaturated vapor; and (ii) for the reference stable equilibrium state the Fisher theory of condensation is used in order to obtain a self-consistent definition of the free-energy barrier for l-cluster formation, where l is the number of molecules in the cluster. A comparison of the expressions for the nucleation rate and critical cluster size with the corresponding classical expressions has been made for the different parts of the phase diagram (temperature-supersaturation) and the domain where both theories are close has been found. Predictions of the present theory have been compared with the experimental results on nucleation of n-nonane for the three sets of experiments (diffusion cloud chamber, fast-expansion cloud chamber, and two-piston cloud chamber). It has been shown that the present theory has a much better agreement with experimental results for n-nonane than the classical theory.