Interfacial Properties of Soft Matter Thin Films Studied by X-ray Reflectivity

A device for surface study of confined micron thin films in a total internal reflection geometry

“…2,3 In order to use SFG to perform these measurements in total internal reflection geometry, it is necessary to devise an apparatus that can bring two macroscopic surfaces, one consisting of a prism and one of a flat plate, to a controlled and parallel separation. Though similar parallel plate instruments have been developed to perform optical, 4 neutron, 5 and x-ray measurements, 6,7 none allows the use of optical total internal reflection to characterize the surface of the confined film. Also, the surface force apparatus used to study confined fluids requires a crossed cylinder geometry and has a typical contact area of Ͻ100 m, 8 making it difficult to probe surfaces using optical techniques.…”

“…Because of the inherent surface sensitivity of SFG, the apparatus developed in this article allows the study of the surface of a confined film in a static or dynamic state, whereas neutron or x-ray measurements can only be used to characterize the bulk of the film using similar apparatuses. [5][6][7] There were two main challenges to overcome for the successful development of the experimental apparatus. The first challenge was to devise a protocol to measure the separation and parallelity of two surfaces, one consisting of a prism and the other a flat plate.…”