We have applied an extension of a microscopic model to account for the nucleation of n-nonane. We have compared the nucleation rates obtained using the extended model with those of two experimental investigations. The results of the two experimental investigations are consistent. The nucleation rates predicted by the classical theory are inconsistent with experimental data and can vary by as much as 14 orders of magnitude. The extended model yields nucleation rates which are in close agreement with the two experimental works.

The Gibbs free formation energies and the energies of formation for argon clusters having 3–19 atoms have been computed. These calculations have been carried out for the free cluster (atomistic) model and the model of interacting monomers and clusters (IMC). In the IMC model the interactions among background monomers and monomer–cluster interactions are considered. However, for the results presented in this work, only the effect of the interactions among background monomers has been computed. Comparison of the free cluster model with the IMC model indicates that even for argon the interactions among background monomers should not be ignored. The results of both models become almost identical at high temperatures. The depletion of monomers has also been considered. A simple relation is given which describes how background monomers are depleted in a supercooled system. The depletion of background monomers can easily be incorporated into the rate of nucleation and, when performed, this introduces a temperature-dependent correction to the nucleation rate.

Easily demonstrable relationship between the microscopic and macroscopic theories of type II superconductivity Am.A micros~~pic model of homogeneous nucleation is ext~nded to apply to macroscopic clusters.The defimtlon used for physical clusters is identical to that of Reiss, Katz, and Cohen, which . has also been introduced by Lee, Barker, and Abraham. Practical approximations have been employed to obtain results in closeq form. The Gibbs free formation energy and the nucleation rate are easil.y calculated in this approach. The extended macroscopic treatment is compared to recent expenmental data for methanol and ethanol. In these cases, the calculated nucleation rate agrees well with the experimental data. The agreement in both cases is consistent and far better than the classical theory.590

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Articles you may be interested inVariable behavior of the current exponent in a microscopic nucleation model for electromigrationThe properties of ion clusters and their relationship to heteromolecular nucleationWe have extended the microscopic model of homogeneous nucleation to the heteromolecular case. This model, interacting clusters and heteroclusters (ICH), consists of a distribution of heteroclusters and clusters. The interaction between monomers, cluster-monomer, heterocluster-monomer, and heterocluster-heterocluster are taken into account. The method of correlation functions is extended so that configuration integral of the ICH model can be calculated. The concentration of heteroclusters is derived in terms of microscopic quantities. In the limit of no interaction between clusters and heteroclusters, the heterocluster concentration is expressed in terms of monomer concentration, the chemical potential of monomers, and the internal free energy of a heterocIuster. In this limit the heterocluster concentration may also be expressed in terms of the total number of ions and the internal free energy ofheteroclusters. The formation energy of a heterocluster is calculated.