PNNL

Abstract

Vapor to liquid nucleation is a dynamical process governed by a delicate interplay between condensation and evaporation rates. Since the vapor is comprised essentially of monomers, the formation of clusters is governed by monomer association and dissociation reactions. The formation of a cluster is impeded by a free energy of activation that is entropic in nature since no potential energy barrier exists. Variational transition state theory provides a framework in which equilibrium evaporation rate constants can be calculated and the corresponding condensation rate constants determined from detailed balance. The nucleation rate can then be obtained by solving the pseudo-first order kinetic equations. The rate constants governing the multi-step kinetics of small water cluster nucleation including the possible role of contaminants will be presented. In addition, the limiting behavior of the rate constants and a sensitivity analysis of the steady-state nucleation rate on these rate constants will be discussed.