The forming process of bubble domains observed in a large pitch cholesteric is investigated under various circumstances. In this experiment the bubble domians of a negative dielectric anisotropy are formed by an application of an electric field below that required for dynamic scattering. The domains of a positive dielectric one are formed by applying thermal turbulence. It is found that the bubble domains are formed through the inherent or field-induced striped texture. The change from stripe to bubble and the reversed change are directly observed. These observations allow one to determine the molecular alignment in the domains. The stability of bubble domains also is discussed.

The texture change in smectic A-cholesteric mixed liquid crystals has been investigated during a rapid cooling process from a cholesteric to a smectic A phase. At the cooling rate of 50°C/min, the initial focal conic texture in the cholesteric phase was transformed to the smectic scattering texture consisting of packed small domains.

The light-scattering characteristics of smectic A liquid crystals are investigated. In the case of an electrooptic effect, the scattering texture is produced through either the field effect or the current effect. It is found that the textures formed due to this effect give rise to diffusive scattering patterns resulting from multiple scattering in the structure. In the case of a thermooptic effect, the scattering texture is obtained through the phase transition from a nematic to a smectic A phase. The textures formed as a result of the thermooptic effect exhibit higher diffraction peaks correlating to the shape of the domains. The scattering characteristics are found to depend on the process which forms the textures.

The effect of magnetic field on the molecular alignment of ferroelectric liquid crystals is observed on the cooling process from an isotropic phase to a chiral smectic C phase. In a sample having phase sequences I-N*-SA-SC *, the monodomain is formed under the magnetic field. The texture change relating to the deformation of the helical structure is investigated in the monodomain. When a d.c. voltage is applied in the SC * phase, the focal conics appear at a low voltage range below the threshold for unwinding of the helix. While the voltage is decreased after the unwinding, the helical structure begins to form from the focal conics. The electrooptic effect induced by the deformation of the helical structure depends on the molecular alignment in the SC * phase.

From single crystals of trans(Cl)-[CoCl2(NH3)3(H2O)]Cl, thin sections with different orientations and different thicknesses were prepared, and their polarized absorption spectra were examined in the 350–850 nm region using a microspectrophotometer. Two absorption peaks, caused by the (x2−y2 ← xy)-type transitions of the d-electrons of Co, were found: a 15750 cm−1 peak was assigned to overlapping A2 ← A1 and B2 ← A1 type transitions of the complex ion with C2v symmetry; a 19210 cm−1 peak was assigned to a B1 ← A1 type transition. The molar extinction coefficients (ε) were determined at each of these peaks: ε(||c) = 104 and ε (⊥c) = 16 l cm−1 mol−1 at 15750 cm−1, and ε(||c) = 5 and ε(⊥c) = 54 l cm−1 mol−1 at 19210 cm−1. These ε values were explained by taking distortions of the d-electron orbitals into consideration, that are partly caused by the oxygen atom coordination and partly by some vibronic couplings between the d-electron orbitals and cobalt-ligand stretching vibrations.