PROPERTIES OF LIQUID-LIQUID INTERFACES ANALYZED BY LIGHT SCATTERING SPECTRA OF CAPILLARY WAVES

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Spectra of the capillary waves at liquid surfaces were measured by light scattering spectroscopy based on the heterodyne detection. The resultant spectra were compared with hydrodynamic theories. The surface tension and viscosity obtained as best-fit parameters by using a simple Lorentzian function and by a more accurate formulation based on the Fourier transform of the correlation function were compared. The surface tension determined by the latter theory agreed very well with the literature data. We obtained the capillary wave spectra for various liquid-liquid liquid interfaces, and the interfacial tension was determined by fitting to the hydrodynamic theory. The method has the advantage of non-contact measurement of the interfacial tension and is applicable to a wide variety of liquid-liquid interfacesWe examined the parachor assigned to fluorine atoms in fluorinated alkanes, and found that the value varies systematically with the number of fluorine atoms in the molecule. This suggests the lowering of the free energy by microscopic structure formation more in the bulk liquid than at the surface. Furthermore, molecular orientation at a liquid surface was studied by a lattice gas model, in which an orientational molecular interaction was assumed. The ordering of molecules near the surface is calculated, and it was shown that the orientational interaction can contribute to the surface tension, or the surface free energy.From a point of view of photochemistry at interfaces, we investigated laser ablation at solid-liquid interfaces. It was found that the ablation plume produced at the interface shows high temperature and high pressure, which has a potential to be applied to a new process for material synthesis.