title: Microscopic structure of the wetting film at the surface of liquid Ga-Bi alloys
abstract: X-ray reflectivity measurements of the binary liquid Ga-Bi alloy reveal a dramatically different surface structure above and below the monotectic temperature T(mono) = 222 degrees C. A Gibbs-adsorbed Bi monolayer resides at the surface in both regimes. However, a 30 A thick, Bi-rich wetting film intrudes between the Bi monolayer and the Ga-rich bulk for T>T(mono). The wetting film's internal structure, not hitherto measured, is determined with A resolution, showing a concentration gradient not predicted by theory and a highly diffuse interface with the bulk phase.
authors.affiliation: Division of Applied Sciences and Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA.
authors.initials: H
authors.lastname: Tostmann
authors.initials: E
authors.lastname: DiMasi
authors.initials: OG
authors.lastname: Shpyrko
authors.initials: PS
authors.lastname: Pershan
authors.initials: BM
authors.lastname: Ocko
authors.initials: M
authors.lastname: Deutsch