title: Two-dimensional freezing in the liquid-vapor interface of a dilute Pb:Ga alloy.
abstract: We report the results of x-ray reflectivity and grazing incidence x-ray diffraction studies of the liquid-vapor interface of a dilute alloy of Pb in Ga over the temperature range of 23-76 degrees C. Our data show that the liquid-vapor interface of this alloy is stratified for several atomic diameters into the bulk liquid and that a monolayer of Pb forms the outermost stratum of the interface. Over the temperature range of 23-56 degrees C, the monolayer of Pb is in an ordered hexagonal phase. At about 58 degrees C, this monolayer undergoes a first-order transition to a hexatic phase, which remains stable to 76 degrees C. An analogy between the observed transition and the first-order melting transition in a one-component classical plasma is suggested.
authors.affiliation: Department of Chemistry and The James Franck Institute, University of Chicago, Chicago, IL 60637, USA.
authors.forename: B
authors.initials: B
authors.lastname: Yang
authors.forename: D
authors.initials: D
authors.lastname: Gidalevitz
authors.forename: D
authors.initials: D
authors.lastname: Li
authors.forename: Z
authors.initials: Z
authors.lastname: Huang
authors.forename: S A
authors.initials: SA
authors.lastname: Rice