摘要:

Geometrical models of blue phases usually proposed a description with double twist cylinders. This description was first complemented by introducing minimal surfaces as midway surfaces between the axes of the double twist cylinders. Here we extend the description to any surface. We give the energy expression and its minimization in terms of specific properties of surfaces. We find the tangent director field minimizing the elastic energy for surfaces with constant mean curvature.

ISSN:1058-725X    

DOI:10.1080/10587259208037263

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Non-rigid symmetry of some moleoular crystals having disordered phases has been studied. Classification of librational-rotational movements of molecular group has been carried out. As a result, the selection rules for disordered crystals for IR and Raman spectra of KSCN crystal in disordered phase are investigated and analysed. They are treated mainly according to the selection rules in the factor-group representation.

ISSN:1058-725X    

DOI:10.1080/10587259208037264

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The experimental investigation of surface polarization by modulation spectroscopy of electro-reflection from the nematic liquid crystal-semiconductor interface and capacitance modulation spectroscopy of direct piezoeffect in nematics has been carried out. The models of surface polarization with induced polar order parameter have been suggested.

ISSN:1058-725X    

DOI:10.1080/10587259208037265

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Depolarized light scattering (DRS) and ultrasonic measurement on isooctane/lecithine/water gel are reported as a function of temperature. The analysis of the DRS data reveals a fast contribution connected to the pure isooctane. The ultrasonic normalized absorption data clearly show a relaxation process. A tentative interpretation of the results is performed on the basis of existing models.

ISSN:1058-725X    

DOI:10.1080/10587259208037266

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The orientational order of a compound exhibiting nematic, SAdand reentrant nematic mesophases was studied through the analysis of proton spectra of the molecular core and deuterium spectra of the chain. The results are compared with the different theoretical models for the SAdphase. Simulations of the proton spectra yield the molecular core order parameters and rule out some of the models proposed, favoring others. Dynamical information regarding the life times of the different molecular aggregates proposed to exist in the SAdphase is obtained from the deuterium spectra of the chain.

ISSN:1058-725X    

DOI:10.1080/10587259208037267

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The Kerr constant of two monotropic nematogens with different molecules length is measured. The low temperature of the nematic-isotropic liquid phase transition which is typical for monotropic LC created the conditions for the observation of two Kerr-effect dispersions at the frequency lower than 10 MHz. It was shown that the low frequency dispersion process is connected with cooperational orientational molecules motion whereas high frequency is connected with the rotation of the individual molecules of nematogen.

ISSN:1058-725X    

DOI:10.1080/10587259208037268

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

We show that in polymer dispersed liquid crystals it is possible to use a bias voltage to control the nonlinear optical interaction of two coherent beams. The orientational and thermal properties of the liquid crystal are coupled in such a way that the former ones drive the thermal nonlinearities. The main features of the observed effect are reported.

ISSN:1058-725X    

DOI:10.1080/10587259208037269

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

An aperiodic hybrid alignement can only appear above a critical thickness in a nematic layer with weak anchoring. Here the influence on the critical thickness of a magnetic field normal to the cell plates is reported. Moreover, the existence of periodic solutions, previously found in a hybrid cell without external field, is discussed in the presence of the magnetic field and in the case of strong anchoring at the wall, where the easy direction is unidirectional planar.

ISSN:1058-725X    

DOI:10.1080/10587259208037270

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A general molecular theory of liquid crystal mixtures is presented. The phase transitions between polar and nonpolar smectic phases are discussed. The tricritical point occurence is shown.

ISSN:1058-725X    

DOI:10.1080/10587259208037271

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A comparative study of the birefringence of a thermotropic metallorganic complex and of its free ligand is reported for the first time. Using the method of the total reflection the ordinary and the extraordinary refractive indices of the palladium complexed liquid crystal A'PdA2 and of its free ligand 4-4′-Bis(hexyloxy)-azoxybenzene have been measured as function of temperature. Palladium complexation increases the optical density but decreases the optical anisotropy of the free ligand.

ISSN:1058-725X    

DOI:10.1080/10587259208037272

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor