Laser and Electric Field Induced Kerr Effect Studies on Nematic Liquid Crystals
The optical and d.c. pulsed field Kerr effects have been used to study the pretransitional behaviour in the isotropic phase for both positive (pentyl cyanobiphenyl) and negative (methoxybenzyladine butyl aniline) dielectric liquid crystals. From the dynamic and static measurements both the relaxation time (τ) and the induced birefringence (△n) have been studied as a function of temperature. These results have been examined in terms of the phenomenological Landau - de Gennes model of phase transitions. Finally both 5 CB and MBBA have been studied in solution in CC14 and the sign changes recorded as a function of field frequency and concentration for MBBA are contrasted with those for 5 CB where no such changes are measured. This paper reviews the more important results obtained with the method and such typical liquid crystalline materials.
KeywordsLiquid Crystal Nematic Liquid Crystal Isotropic Phase Kerr Effect Permanent Dipole Moment
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