Optical studies of fluid interfaces

Abstract

Experimental investigation with optical techniques give very useful information on liquid-gas and liquid-liquid interfaces. We have developed a number of these techniques in our laboratory: — ellipsometry, which gives information about interfacial thickness, anisotropy, and roughness; — fluorescence microscopy, which gives information about phase separation in adsorbed layers; — surface light-scattering, which gives information about interfacial tension and surface viscoelasticity; — excited-wave techniques (electrocapillarity, compression) which give the same dynamic information as surface light scattering, but in a different frequency range. The potentials of these techniques will be briefly reviewed and illustrated with results obtained recently in our laboratory in surfactant systems: insoluble monolayers at the free surface of water, soluble monolayers at the free surface of water and oil-water interfaces.