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A new method of rapid and non-contact surface tension measurement based on the ripplon light scattering technique is described. A light beam from a cw-YAG laser with 100 mW output was focused on the surface in a small spot of a diameter comparable to the coherent length of ripplon. A very intense signal of the ripplon light scattering was thus obtained and the time required for the measurement was successfully reduced to ∼5 s. High spatial resolution was also obtained using the focused laser beam. The dispersion relation of ripplon on a pure water surface was measured over a wide frequency range from 10 kHz up to 1 MHz, and the surface tension was determined to be within an accuracy of 1%. The result of surface tension measurement obtained for a water/ethanol mixture is also demonstrated.

The relaxation phenomenon of the surface elasticity was investigated for a soluble mono-molecular layer of sodium dodecyl sulfate (SDS) on aqueous solution. Two kinds of experiments, induced surface wave measurement and ripplon light scattering, were performed at frequencies of 1 kHz and 40 kHz, respectively. In the dilute region below the critical micellar concentration (CMC), the concentration dependence of the surface elasticity obtained at 1 kHz is well explained by the theory of diffusion-dominated relaxation, while the surface elasticity at 40 kHz was found to exceed the low-frequency value, which suggests another relaxation mechanism. The results obtained above the CMC were also presented.

The properties of ferroelectric nanodomains in LiNbO 3 crystals were investigated using scanning force microscopy. In particular, we found differences in the domain shape, domain-wall sharpness, and lateral growth rate of domains in nearstoichiometric and congruent LiNbO 3 crystals. In the near-stoichiometric LiNbO 3 crystal, the domain dots are hexagonal and linear domains with smooth walls can be engineered parallel to one of the crystallographic Y-axes. The shape of the linear domains engineered at an angle to the crystallographic Y-axis changes when a small bias is applied during scanning, and various domain shapes are obtained after being stabilized by scanning. However, in the congruent LiNbO 3 crystal, the domain dots are roughly circular and there is no change in the shape of the linear domains, which have rough domain walls. The lateral growth rate of domains in the congruent LiNbO 3 crystal is smaller than that in the near-stoichiometric LiNbO 3 crystal.

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