Ellipsometric measurement of liquid film thickness

摘要

During the later period of this research project, the system of two components, water and succinonitrile, was subjected to ellipsometric measurement of liquid film thickness at several temperatures for a few concentrations. The experiment was to indirectly estimate the surface pressure of a liquid for a binary monotectic system. The procedure requires determination of the critical wetting temperature for the system by applying Young's equation which describes the relationship among the interfacial free energies: gamma(L(sub 2)2S) = gamma(L(sub 1)S) gamma(L(sub 1)L(sub 2))cos(theta) where theta is the contact angle and gamma is the interfacial energy corresponding to the interface denoted by the liquid L and solid S phases. L(sub 1) and L(sub 2) refer to liquid 1 and liquid 2, respectively. The liquid film from the solutions may be formed by condensation of the vapor or by van der Waals adsorption of the liquid along the container wall. Thus it becomes necessary to estimate partial pressures of each component for each binary solution equilibrated at different temperatures.