Influence of flexoelectric effect on the correlation of thermal director fluctuations in filled nematic liquid crystals

An electric field generated by the deformation of the liquid crystal director in a filled nematic with flexoelectric properties is shown to reduce correlations of thermal director fluctuations. The contribution to the correlation reduction from the flexoelectric mechanism increases with the energy of director anchoring at the surface of impurity particles and may dominate over the contribution from the director interaction with the particle surface in the absence of flexoelectricity. The reduction of the Rayleigh light scattering by thermal director fluctuations in a filled nematic should be higher if the nematic has flexoelectric properties.     

Production and spectroscopy of PbF and SiF radical molecules in low-pressure inductively coupled plasma

A method for producing PbF radical molecules with application of a low-pressure inductively coupled plasma is proposed. The emission spectra of PbF radical molecules have been recorded during decomposition of the PbF₂ compound in plasma. Simultaneously, during excitation of a discharge in a quartz tube, spectra of SiF molecules, excited upon interaction of free fluorine with the tube walls, were recorded. Quantum-mechanical calculation of the Franck-Condon factors has been perform to identify the observed spectra.     

New self-developing photopolymers for holographic recording in the 500–700 nm range

The methods of sensitization in the visible spectral region of self-developing photopolymeric materials on the basis of oligoether- and oligourethane acrylates have been investigated. As a result of the choice of the initiating system and modification of the monomer component of the base FPK-488, new FPK-520 and FPK-650 compositions have been obtained that provide holographic recording in the 500–700 nm range. The compositions developed can be used to record holographic optical elements (gratings, lenses) as well as for holographic interferometry and in pattern recognition systems. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 1, pp. 29–33, January–February, 2000.     

Characteristics of photopolymer holographic matched filters in a van der Lugt correlator

Parameters of van der Lugt holographic matched filters for phase and amplitude transparencies, including random phase masks, are studied. Conditions for recording such filters in a phase self-developing photopolymer are determined. A significant difference in the recording conditions for the holographic filters for amplitude transparencies and phase masks is demonstrated. The holographic filters for phase masks with a signal-to-noise ratio of 20–40 dB and η from 6 to 70% that are recorded in the photopolymerizable composition seem to be promising for optical pattern recognition.     

Influence of Secondary Diffraction Orders on the Quality of Image Formed by a Mid-IR Refractive–Diffractive Optical System

Optics and Spectroscopy - The influence of secondary diffraction orders of a diffraction corrector of chromatic aberration on the quality of an image near the optical axis formed by a...     

β-BBO,LBO, AND KTP Nonlinear Crystals as Sources of Millimeter-Wave Radiation

Russian Physics Journal - The refractive indices and the absorption coefficients of β-BBO, LBO, and KTP nonlinear optical crystals have been measured in the wavelength range of 0.5–3 mm...     

Induced Absorption Spectra of a Crystal Violet Dye

Russian Physics Journal - Using the pump-probe method, the short-lived induced and long-lived absorption capacity of a crystal violet (CV) dye is studied in various solvents. The solvents selected...     

Stable nonequilibrium composites based on liquid-crystalline polymers and cadmium selenide nanoparticles

On the basis of copolymers of 4-methoxyphenyl-4-(6-(acryloyloxyhexyloxy)benzoate with 4-(6-acryloyloxyhexyloxy)benzoic acid, nonequilibrium composites containing nanoparticles (quantum dots) of cadmium selenide at concentrations many times higher than their solubility limit in the liquid-crystalline phase are synthesized. In the resulting material, the polymer matrix undergoes the transition to the liquidcrystalline state before separation into phases with concentrations of nanoparticles corresponding to thermodynamically equilibrium values. Under common conditions, the composites are stable for at least several months.     

Surface-plasmon vortices in nanostructured metallic films

Light scattering by a small protrusion on a metal surface is analyzed within the framework of perturbation theory. Upon normal incidence of a linearly polarized monochromatic wave, slight deviations of the protrusion’s shape from a circularly symmetric one lead to the formation of optical vortices in the near-field region due to resonant excitation of circular surface plasmons. This agrees with the results of scanning near-field optical microscopy experiments revealing distinct spiral patterns in the in-plane near-field intensity distribution for metallized nanostructured polymer substrates.     

Refinement of molecular constants of neodymium triiodide by electron diffraction

The molecular structure of neodymium triiodide has been studied by electron diffraction. The molecule has D_3h symmetry; the equilibrium intemuclear distance is R_e(Nd-I) = 286.6(5) pm. The deformation frequencies are estimated from the experimental mean square vibration amplitudes and stretching frequencies. Translated from Zhurnal Strukturnoi Khimii, Vol. 41, No. 4, pp. 725-729, July-August, 2000