Eur. Phys. J. B 10, 45-52 (1999)
https://doi.org/10.1007/s100510050828

Interfacial roughness in a near-critical binary fluid mixture: X-ray reflectivity and near-specular diffuse scattering

Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307, USA

Corresponding author: ^a mcclain@xtal200.harvard.edu

Received: 1 April 1998
Published online: 15 July 1999

Abstract

Measurements are presented of the X-ray specular reflectivity and near-specular diffuse scattering of the interface in a near-critical mixture of hexane and perfluorohexane. A lineshape analysis of the scattered intensity at each temperature yields values for the interfacial tension and interfacial width. The temperature variation of the tension and width so-obtained are consistent with current understanding of this interface, which holds that there is, firstly, an intrinsic width over which the fluid density varies smoothly from one coexistence composition to the other, and, secondly, that the interface acquires an additional and larger statistical interfacial width as a result of capillary fluctuations.