Pairing Interactions and Gibbs Adsorption at the Liquid Bi-In Surface: A Resonant X-Ray Reflectivity Study

E. DiMasi; H. Tostmann; O. G. Shpyrko; P. Huber; B. M. Ocko; P. S. Pershan; M. Deutsch; L. E. Berman

doi:10.1103/PhysRevLett.86.1538

Pairing Interactions and Gibbs Adsorption at the Liquid Bi-In Surface: A Resonant X-Ray Reflectivity Study

E. DiMasi, H. Tostmann, O. G. Shpyrko, P. Huber, B. M. Ocko, P. S. Pershan, M. Deutsch, and L. E. Berman

Phys. Rev. Lett. 86, 1538 – Published 19 February 2001

Abstract

Resonant x-ray reflectivity measurements from the surface of liquid ${Bi}_{22} {In}_{78}$ find only a modest surface Bi enhancement, with $35 at . %$ Bi in the first atomic layer. This is in contrast to the Gibbs adsorption in all liquid alloys studied to date, which show surface segregation of a complete monolayer of the low surface tension component. This suggests that surface adsorption in Bi-In is dominated by attractive interactions that increase the number of Bi-In neighbors at the surface. These are the first measurements in which resonant x-ray scattering has been used to quantify compositional changes induced at a liquid alloy surface.

Received 2 August 2000

DOI:https://doi.org/10.1103/PhysRevLett.86.1538

Authors & Affiliations

E. DiMasi^1,*, H. Tostmann^2,†, O. G. Shpyrko², P. Huber², B. M. Ocko¹, P. S. Pershan², M. Deutsch³, and L. E. Berman⁴

¹Department of Physics, Brookhaven National Laboratory, Upton, New York 11973
²Division of Engineering and Applied Sciences and Department of Physics, Harvard University, Cambridge, Massachusetts 02138
³Department of Physics, Bar-Ilan University, Ramat-Gan 52900, Israel
⁴National Synchrotron Light Source, Brookhaven National Laboratory, Upton, New York 11973

^*Author to whom correspondence should be addressed. Electronic address: dimasi@bnl.gov
^†Present address: Department of Chemistry, University of Florida, Gainesville, Florida 32611.