摘要:

The helical twisting power of chirally substituted mono- and bis- aminoanthraquinones in ZLI 1695 is only weakly temperature dependent. An exception are the naphthyl substituted compounds where the temperature dependence is correlated with the temperature dependent equilibrium between at least two conformers.

ISSN:1058-725X    

DOI:10.1080/10587259508033467

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The analysis of a nonlinear directional coupler consisted of two planar waveguides separated by a nematic liquid crystal is presented. The nonlinear effect is caused by an optically-induced reorientational effect occurring in hybrid aligned nematics. The asymmetrical configuration causes the nonreciprocity in switching characteristics of the directional coupler.

ISSN:1058-725X    

DOI:10.1080/10587259508033468

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The critical behaviors of the linear and higher-order nonlinear dielectric constants of ferroelectric liquid crystals (FLCs) are studied in the SmA phase near the SmA-SmC* phase transition. The critical exponents of the linear, third-order and fifth-order dielectric constants experimentally obtained are 1, 4 and 7, respectively. These exponents and the signs of nonlinear dielectric constants are in good agreement with those calculated theoretically from the phenomenological theory of Landau type. The influence of the order of phase transition (first or second) on the critical behavior of FLCs is also studied.

ISSN:1058-725X    

DOI:10.1080/10587259508033469

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

An anomalous selective reflection more then 50% of input unpolarized light was observed near the cholesterio to smectio A phase transition in three-active non-mesogenic dopant.

ISSN:1058-725X    

DOI:10.1080/10587259508033470

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Orientational order parameters (OOP) in the smectic C and nematic phases of heptyloxyazoxybenzene (HAB) have been determined from x-ray diffraction and refractive index studies. Order parameters determined from x-ray studies have been corrected for the random orientation of the director in a cone in the smectic C phase of HAB. The causes of discrepancy between the experimental and theoretical OOP values have been discussed.

ISSN:1058-725X    

DOI:10.1080/10587259508033471

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A comparative study of transient photoconductivity and dark conductivity in the discotic liquid crystal hexahexyloxytriphenylene (HAT6) is reported. In both experiments the transport is dispersive, and the carrier mobilities are essentially identical demonstrating that the presence of the counterions in the chemically doped conductors does not significantly perturb the mobility.

ISSN:1058-725X    

DOI:10.1080/10587259508033472

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A low power He-Ne laser beam is shown to induce layer instabilities in a smectic A liquid crystal cell possessing initial homeotropic orientation. The effect occurs when the smectic A phase is doped with a photosensitive azo-compound. The most plausible mechanism for the instability is photo-transformation of the guest molecules (e.g. trans-cis isomerization), and a subsequent decrease in the smectic layer spacing.

ISSN:1058-725X    

DOI:10.1080/10587259508033473

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

New three-component liquid crystal systems creating spontaneously nematoid-type filaments at the transition from the isotropic melt and formation of the nematoid-type filaments at the nematic - smectic A transition in dilute solutions of smectogen in silicon oil are reported. We have observed over 50 new three-component systems, composed of smectogen, nematogen and chiral dopant, in which the formation of the nematoids occurs. The plate-type nucleation of the mesomorphic phases has been observed at the transition from the isotropic melt for pure smectogens and also for three-component systems. In addition, creation of the nematoid-type filaments in dilute solutions of mesogen (NPOOB) in sicon oil has been observed here. Early stages of the plate-type nucleation have been examined using Nomarski contrast. The refractive profiles of the filaments have been examined using double-refracting microinterferometers.

ISSN:1058-725X    

DOI:10.1080/10587259508033474

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

We present the results of optical investigations of transient patterns appearing during the reorientation of nematic LC in magnetic fields. The transition from a planar modulated director field to a metastable non-planar structure of twist-bend walls is observed. From the wavelengths and characteristic rise times of the investigated patterns, the validity of the linearized mode selection theory is confirmed and viscoelastic parameters are determined.

ISSN:1058-725X    

DOI:10.1080/10587259508033475

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

We present a novel method for spatially resolved measurements of the amplitudes of thermal fluctuations and surface pretilt angles in thin cells filled with nematic liquid crystals (LC).

ISSN:1058-725X    

DOI:10.1080/10587259508033476

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor