Microscopic structure of the wetting film at the surface of liquid Ga-Bi alloys
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.
Tostmann
H
Division of Applied Sciences and Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA.
DiMasi
E
Shpyrko
OG
Pershan
PS
Ocko
BM
Deutsch
M