Orientational distribution function in nematic liquid crystals by x-rays: Fourier method

The existing methods for the determination of the orientational distribution function f(beta) in the nematic liquid crystals using X-rays have been reviewed. A simple Fourier method which gives f(beta) in terms of the measured intensity is analysed. Using this distribution function, the accuracy with which the order parameters could be evaluated is discussed and the results show the elegance of the Fourier method used here

Dielectric investigations in the nematic and hexatic smectic B phases of 4-hexyl-4'-2-(4-isothiocyanatophenyl)ethyl]-1,1'-biphenyl

Temperature-dependent dielectric characterization of 4-hexyl-4'-2-(4-isothiocyanatophenyl)ethyl]-1,1'-biphenyl (HIEB), which exhibits smectic B and nematic phases, has been carried out over the frequency range of 1 Hz to 10 MHz for homeotropic and planar alignment of sample molecules. This compound shows positive dielectric anisotropy ( = - 0) in the nematic (N) phase. One mode of dielectric relaxation showing Arrhenius behaviour has been detected in the hexatic smectic B (SmB) phase. Various electrical parameters, namely, dielectric anisotropy, relaxation frequency and activation energy, have been determined in the N and SmB phases

Birefringence of some nematic compounds

This paper reports the refractive index and density data and discusses the orientational order parameters in the case of the following eight nematic compounds, viz., (1) p(p-ethoxyphenylazo) phenyl valerate, (2) p(p-ethoxyphenylazo)phenyl hexanoate, (3) p(p-ethoxyphenylazo)phenyl heptanoate, (4) p(p-ethoxyphenylazo)phenyl undecylenate, (5) 4,4'-bis(hexyloxy)azoxybenzene, (6) 4,4'-bis(heptyloxy)azoxybenzene, (7) anisylidene-p-aminophenyl acetate, and (8) anisylidene-p-aminophenyl butyrate