Susceptibility nematics

The magnetic susceptibilities of some ether-type liquid-crystalline polymers are measured by a SQUID magnetometer. The Ax values estimated for the stable nematic state are analyzed according to a known RIS scheme. 

Photochemically induced phase transition photochemical phase transition) of LCs in guest/host systems is interpreted as follows. 81 If a small population of photochromic compounds such as azobenzene are dispersed in nematic LCs (NLCs), the phase structure of the NLCs is susceptible to change induced by photochemical reac-... 

Anisotropic molecules show optically isotropic behavior in the bulk when they are disordered and randomly oriented, for instance in solutions or liquid crystal above the transition temperature. Under the influence of a strong beam, the induced dipole moment of the molecules feels a torque that tends to orient the molecule. The reorientation of the molecular dipoles induces a change in the refractive index. The typical values for molecular susceptibilities and the time-responses vary depending on the type of systems. For small anisotropic molecular systems, x 10 esu, with a time response 10 s. However, in the nematic phase, liquid crystal molecules are strongly correlated, resulting in much higher values, x 10 esu,... 

The third NLO susceptibility may not be zero even though the molecular orientation is completely randomly distributed, i.e., in an isotropic state. The highly ordered phase usually has a high value for the third NLO coefficient. For example, the highly ordered nematic phase has a third NLO coefficient five times that in the isotropic phase. 

From X-ray diffraction experiments carried out on a few of these complexes [60, 61], it was also deduced that the copper complexes of the series 29 possessed a negative anisotropy of the magnetic susceptibility, while it was positive for all the other complexes 29 and 30. Chiral nematic phases (and blue phases in some examples) have also be obtained by replacing the linear alkyl group by a chiral chain in the complexes 29 [62]. 

The order parameter can be directly related to certain experimentally determinable quantities - say, for example, the diamagnetic anisotropy of the liquid crystal.Let us choose a space-fixed cartesian coordinate system xyz with z parallel to n. If and are the principal diamagnetic susceptibilities of the molecule referred to its own principal axes, the average z component of the susceptibility per unit volume in the nematic phase is evidently... 

Fig. 5.5.2. Temperature dependence of the susceptibility Of) and the correlation lengths if and for smectic A short-range order in the nematic phase of butoxybenzylidene-octylaniline. Open circles were deduced from X-ray scattering, and filled circles from light scattering. The smectic density wavevector remains...

As the dielectric constant and diamagnetic susceptibility of many mesogens are anisotropic, the orientation of side-chain LCPs in the nematic state can also be changed by the application of a magnetic... 

A. V. Sukhov and R. V. Timashev, "Optically Induced Deviation from Central Symmetry Lattices of Quadratic Nonlinear Susceptibility in a Nematic Liquid Crystal," JETP Lett., Vol. 51, No. 

Third-Ordered Susceptibilities of Nematic and Isotropic Solutions of a Rodlike Polymer (PBT)... 

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