A REFINED DROPLET APPROACH TO THE PROBLEM OF HOMOGENEOUS NUCLEATION FROM THE VAPOR-PHASE

A theory of homogeneous nucleation from the vapor phase is presented, which is based on an extension of Fisher's semiphenomenological droplet model for the Gibbs free energy of formation of a cluster. This droplet model allows translational, rotational, vibrational, and configurational degrees of freedom of the cluster as well as the variation of surface tension with cluster size. By suitable choice of the three free model parameters, known nucleation theories such as the classical Becker-Doring-Zeldovich theory and others are obtained as special cases. Since, however, an ansatz for the Gibbs free energy of formation allows the construction of an equation of state for real gases below the critical point, a new method of determining the model parameters is suggested, which is based on the idea of forcing the identity of the constructed equation of state with an experimentally verified one. Thus, all free model parameters can be determined purely from well-known handbook properties. It is shown that the new theory gives a better prediction of observed nucleation rates than the classical one.