Search results for "WAVES"
showing 10 items of 1766 documents
Multilayers of CdSe/CdS/ZnCdS Core/Wings/Shell Nanoplatelets Integrated in a Polymer Waveguide
2017
In this work, fabrication of multilayers of colloidal CdSe/CdS/ZnCdS core/wings/shell nanoplatelets (NPls) on solid substrates by layer-by-layer deposition technology is successfully demonstrated for the first time. Integration of multilayers of nanoplatelets into polymeric waveguide resulted in strong dichroism in absorption and polarization effects in photoluminescence with preferable absorption and emission of TE (horizontal) mode that evidences about in-plane orientation of NPls relative to the planar waveguide. The propagation of the excitation and emission light along the waveguide was thoroughly investigated both theoretically and experimentally for different number of NPl layers.
Effects of solvent-free microwave extraction on the chemical composition of essential oil of Calamintha nepeta (L.) Savi compared with the convention…
2008
The essential oil of Calamintha nepeta has been obtained by solvent-free microwave extraction (SFME) and by classical hydrodistillation (HD). A comparative qualitative-quantitative study on the composition of the oils was carried out. A total of 38 compounds, constituting 97.6% of the oil, were identified in the oil obtained by SFME, whereas 46 compounds, representing 95.4% of the oil, were characterized in the HD oil. SFME-distilled oil is richer in lightly oxygenated monoterpenes (LOM) than HD oil. It also has a higher amount of sesquiterpenes and a lower quantity of hydrocarbon monoterpenes. HD oil seems to be affected by chemical changes more than SFME oil.
Photoinduced mass transport in soft materials
2011
The surface relief grating formation in amorphous As2S3 and azo-benzene polymer films strongly depends on the polarization state of recording beams. The surface relief grating formation efficiency of s-s and p-p recording beam combination can be essentially enhanced by additional illumination with orthogonal polarization. It is shown that the direction of mass transport on the film surface is determined by the direction of light electric vector.
Polarization holographic recording in Disperse Red1 doped polyurethane polymer film
2011
In this report holographic recording of polarisation and surface relief gratings in Disperse Red 1 (DR1) doped polyurethane polymer films was studied. In this material DR1 is chemically bounded to polyurethane polymer main chain. Polarization holographic recording was performed by two orthogonal circularly polarized 532 nm laser beams. Photoinduced birefringence is a precondition for polarization holograms recording, therefore a detailed study of a photoinduced birefringence and changes of optical properties was performed. The lasers with wavelengths of 375nm, 448nm, 532 nm and 632.8 nm were used as pumping beam for sample excitation. The photoinduced birefringence Δn was measured at 532 nm…
Simulation of Dense Polymer Systems in Two and Three Dimensions
1991
Dense polymer systems are modeled by self- and mutually avoiding walks on lattices. Both simple models where the step length is one lattice spacing and more complicated models where the step length is distinctly longer and may fluctuate (“bond fluctuation model”) are discussed, and it is shown that the computer simulation of such models gives useful insight to understand the thermodynamic phase behavior and the relaxational dynamics of dense polymer solutions and polymer melts. The huge demands in computing power needed for a successful simulation of such systems can be covered by parallel computers such as the multitransputer facility of the University of Mainz.
Optical Field-Induced Mass Transport in Soft Materials
2013
Abstract The dependence of the surface relief formation in amorphous chalcogenide (As 2 S 3 and As-S-Se) and Disperse Red 1 dye grafted polyurethane polymer films on the polarization state of holographic recording light beams was studied. It is shown that the direction of lateral mass transport on the film surface is determined by the direction of light electric vector and photoinduced anisotropy in the film. We propose a photoinduced dielectropfhoretic model to explain the photoinduced mass transport in amorphous films. Model is based on the photoinduced softening of the matrix, formation of defects with enhanced or decreased polarizability, and their drift under the electrical field gradi…
Double-quantum nutations in a two-level spin system
1986
The transient oscillatory behavior of the nonlinear response of a two-level electron-spin system is experimentally investigated in a sample of glassy silica with ${E}_{1}^{\mathcal{'}}$ centers (S=(1/2)) at microwave frequency at T=4.2 K. The transient regime, excited by an intense step-modulated radiation tuned to double-quantum (DQ) resonance, is monitored by revealing the second-harmonic (SH) wave radiated by the spins undergoing DQ transitions. Time- and frequency-domain results show that the emitted SH wave has two components: the former, which vanishes at the DQ resonance, exhibits an overdamped transient regime, the latter consists of damped oscillations at a frequency which depends …
Effect of traditional, microwave and industrial cooking on inositol phosphate content in beans, chickpeas and lentils
2003
An high-performance liquid chromatography method for determining inositol phosphate fractions was adapted to legumes. The validity of the method was assessed by estimating the following analytical parameters: linearity (linear response between 125 and 5000 microg inositol hexaphosphate (IP(6))/ml); instrumental precision and method precision (relative standard deviation, %) were 1.9% (IP(6)) for instrumental, and 2.5% (IP(6)) and 8.2% (IP(5)) for method precision. An accuracy was estimated by percentage recovery (72 +/- 3%). The application of this method to raw, conventional, microwave-cooked and ready-to-eat beans, chickpeas and lentils gave IP(6) contents ranging from 0.63 g/100 g dry ma…
Single molecule probing of dynamics in supercooled polymers
2011
6 pages; International audience; Fluorescence experiments with single BODIPY molecules embedded in a poly(methyl acrylate) matrix have been performed at various temperatures in the supercooled regime. By using pulsed excitation, fluorescence lifetime and linear dichroism time trajectories were accessible at the same time. Both observables have been analyzed without data binning. While the linear dichroism solely reflects single particle dynamics, the fluorescence lifetime observable depends on the molecular environment, so that the dynamics from the polymer host surrounding a chromophore contributes to this quantity. We observe that the lifetime correlation decays slightly faster than polar…
Insight in NLO Polymer Material Behavior from Langevin Dynamic Modeling of Chromophore Poling
2011
Calculation of chromophore polar order, i.e. the polarization of nonlinear optically (NLO) active polymers poled by external field, is challenging. One possible solution is to reproduce the orientation polarization of chromophores under external field using Langevin dynamics (LD) molecular modeling. The present work investigates the influence of chromophore dipole moment, density and field extent on NLO efficiency and polarization/relaxation dynamics. Results of simulations convince us, that the method is applicable for modeling real NLO polymers. In the spotlight of this investigation we would like to describe a NLO polymer as a “ferrofluid” where chromophores are active particles or elect…