title: Nonclassical "explosive" nucleation in Pb/Si(111) at low temperatures.
abstract: Classically, the onset of nucleation is defined in terms of a critical cluster of the condensed phase, which forms from the gradual aggregation of randomly diffusing adatoms. Experiments in Pb/Si(111) at low temperature have discovered a dramatically different type of nucleation, with perfect crystalline islands emerging "explosively" out of the compressed wetting layer after a critical coverage Θ_{c}=1.22  ML is reached. The unexpectedly high island growth rates, the directional correlations in the growth of neighboring islands and the persistence in time of where mass is added in individual islands, suggest that nucleation is a result of the highly coherent motion of the wetting layer, over mesoscopic distances.
authors.affiliation: Ames Laboratory-U.S. Department of Energy, Iowa State University, Ames, Iowa 50011, USA and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA.
authors.forename: M T
authors.initials: MT
authors.lastname: Hershberger
authors.affiliation: Ames Laboratory-U.S. Department of Energy, Iowa State University, Ames, Iowa 50011, USA.
authors.forename: M
authors.initials: M
authors.lastname: Hupalo
authors.affiliation: Ames Laboratory-U.S. Department of Energy, Iowa State University, Ames, Iowa 50011, USA and Department of Chemistry, Iowa State University, Ames, Iowa 50011, USA and Department of Materials Science and Engineering, Iowa State University, Ames, Iowa 50011, USA.
authors.forename: P A
authors.initials: PA
authors.lastname: Thiel
authors.affiliation: Ames Laboratory-U.S. Department of Energy, Iowa State University, Ames, Iowa 50011, USA.
authors.forename: C Z
authors.initials: CZ
authors.lastname: Wang
authors.affiliation: Ames Laboratory-U.S. Department of Energy, Iowa State University, Ames, Iowa 50011, USA and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA.
authors.forename: K M
authors.initials: KM
authors.lastname: Ho
authors.affiliation: Ames Laboratory-U.S. Department of Energy, Iowa State University, Ames, Iowa 50011, USA and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA.
authors.forename: M C
authors.initials: MC
authors.lastname: Tringides
mesh_terms: D003080:Cold Temperature; D003460:Crystallization; D007854:Lead / Q000737:chemistry*; D012825:Silicon / Q000737:chemistry*
chemical_list: D007854:Lead; D012825:Silicon