Neutron reflectivity studies of adsorption and wetting in the vicinity of a liquid/liquid critical point: alkane + perfluoroalkane mixtures at a silicon interface

Abstract

We report the results of a preliminary investigation by specular neutron reflectivity of adsorption and wetting of alkane + perfluoroalkane binary liquid mixtures in the vicinity of the liquid/liquid critical point against a chemically modified (alkane-like) silicon wall. The results suggest the existence of a surprisingly long-ranged profile , even some degrees Kelvin above the upper critical point, and enable us to detect a wetting layer and its liquid/liquid interface below the critical point. The technique is capable of determining the composition, uniformity, and thickness of the wetting layer.