INFLUENCES OF BINDING TRANSITIONS ON THE HOMOGENEOUS NUCLEATION OF MERCURY

Nucleation rates from supersaturated vapor are calculated for mercury. Previous measurements of nucleation rates using an upward thermal dif fusion chamber demonstrated that critical supersaturations for Hg vapo r are roughly three orders of magnitude lower than the predictions of the classical Becker-Doring-Zeldovich theory. [J. Martens, H. Uchtmann , and F. Hensel, J. Phys. Chem. 91, 2489 (1987)] This discrepancy was attributed to a metal-nonmetal transition in Hg clusters that occurs n ear the critical cluster size. [H. Uchtmann, K. Rademann, and F. Hense l, Annalen der Physik. 48, 207 (1991)] That view is supported by the s imilarity of cohesive energies and optical spectra for Hg clusters and rare gas clusters. [H. Haberland et al., Z. Phys. D 26, 8 (1993)] Usi ng this analogy and the framework of the classical theory, we calculat e nucleation rates that agree with the experiments within experimental uncertainties without any adjustable parameters. (C) 1997 Acta Metall urgica Inc.