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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A light scattering study was made on ripplons generated over the surface of CnTAB (n-cetyltrimethyl ammonium bromide) solutions (in the present case n=14 and 16). After preparing the sample solution we measured its surface tension for 3 h and confirmed that the tension did decrease with time exponentially but very slowly. The relaxation time depended on the surfactant concentration of solutions and increased sensitively with the progress of dilution, e.g., 3 min at 10(-2) mol/l to 80 min at 10(-4) mol/l for C16TAB. The results obtained were correlated with surface adsorption densities estimated from the observed surface pressure vs concentration curves using Langmuir's adsorption equation. Two mechanisms were proposed to interpret such a slow relaxation process: One is a model in which reorientation or redistribution of the surfactant molecules adsorbed on the solution is considered, while the other is a two-state model that assumes the existence of a high energy barrier for surfactant molecules between those on the surface and those in the subsurface. A question still remains as to which of the two is more probable.