Anomalous birefringence of swollen lamellar phases : blue smectics
نویسنده
چکیده
The birefringence of a lyotropic lamellar phase is calculated as a function of dilution. It is found to vanish and change sign, provided the natural birefringence of surfactant bilayers is positive. Dispersion is calculated about the point of zero birefringence. These predictions are illustrated with experiments of spectrophotometry: the intensity of light transmitted between crossed polarizers through several lamellar samples vanishes as expected at some particular wavelength. The dependence of the transmitted light on wavelength and cell thickness is consistent
منابع مشابه
Surface relaxation of lyotropic lamellar phases
– We study the relaxation modes of an interface between a lyotropic lamellar phase and a gas or a simple liquid. The relaxation is found to be qualitatively different from those of both simple liquids and single-component smectic-A liquid crystals. It is governed by a non-inertial, diffusive mode whose decay rate increases quadratically with wavenumber, |ω| = Aq. The coefficient A depends on th...
متن کاملTwo New Topologically Ordered Glass Phases of Smectics Confined in Anisotropic Random Media
Smectics in strained aerogel exhibit two new glassy phases. The strain both ensures the stability of these phases and determines their nature. One type of strain induces an “XY Bragg glass,” while the other creates a novel, triaxially anisotropic “m � 1 Bragg glass.” The latter exhibits anomalous elasticity, characterized by exponents that we calculate to high precision. We predict the phase di...
متن کاملScaling of shear-induced transformations in membrane phases.
Surfactant sponges are complex-fluid phases made up of convolutions of bilayer sheets. Although isotropic and free flowing they exhibit transient birefringence when stirred, reminiscent of the birefringence of lamellar phases. Previous attempts to understand this effect have led to confusing and often conflicting results. We have used a novel approach to designing the chemical system that gives...
متن کاملFractal analysis of lyotropic lamellar liquid crystal textures
We apply fractal analysis to study the birefringence textures of lyotropic lamellar liquid crystal system (water/cethylpyridinium chloride/decanol). Birefringence texture morphologies are important as they provide information on the molecular ordering as well as defect structures and therefore has been adopted as a standard method in characterizing di4erent phases of liquid crystals. The system...
متن کاملChiral Lyotropic Liquid Crystals: TGB Phases and Helicoidal Structures
The molecules in lyotropic membranes are typically aligned with the surface normal. When these molecules are chiral, there is a tendency for the molecular direction to twist. These competing effects can reach a compromise by producing helicoidal defects in the membranes. Unlike thermotropic smectics, the centers of these defects are hollow and thus their energy cost comes from the line energy o...
متن کامل