Ring patterns of concentric 2pi solitons in molecular orientation form in freely suspended chiral smectic-C films in response to an in-plane rotating electric field. We present measurements of the driven dynamics of ring formation under conditions of synchronous winding and of the zero-field relaxation of ring patterns, and propose a simple model which enables their quantitative description in low polarization DOBAMBC. In smectic-C*A TFMHPOBC we observe an odd-even layer number effect, with odd layer number films exhibiting order of magnitude slower relaxation rates than even layer films. We show that this rate difference is due to a much larger spontaneous polarization in odd layer number films.

Several alkenyl diphenyldiacetylene liquid crystals were synthesized and their physical properties evaluated. The introduction of a double bond in the side chain leads to an unexpectedly wide nematic range and an extraordinarily large figure of merit at elevated temperatures. These liquid crystals are particularly attractive for infrared laser-beam steering.

The angular dependence of the critical magnetic field for the unwinding of the Sm-C ‫ء‬ helix of a ferroelectric liquid crystal has been measured by a deuteron NMR sample tilting technique. A minimum at intermediate angles, resulting in a reentrant Sm-C ‫ء‬ Sm-C Sm-C ‫ء‬ behavior, has been observed. The solitonlike deformation of the helix has a 2p symmetry at a general orientation, whereas it has a p symmetry for the magnetic field parallel to the smectic layers. The results can be interpreted in terms of the Landau theory with the inclusion of a nonparallel magnetic field energy term.[S0031-9007(98)06068-2]

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We report on the results of optical, X-ray and NMR studies of light-induced phenomena in smectic phases triggered by molecular phototransformations.UV irradiation causes trans-to-cis isomerization of the dopant molecules while irradiation in thc visible part of the spectrum facilitates cis-to-trans relaxation. Cis-to-trans isomerization decreaws the smectic layers' spacing; as the result, a smectic slab undergoes an undulation instability and/or formation of focal conic domains. These textures arc nonuniform and scatter light; this effect can be used for optical data storage. The opposite trans-to-cis isomerization disorders the orientation of molecules and increases the thickness of smectic layers. Two beams of different wavelengths with distinct yields of isomerisation can be used to write and erase optical information.