Permanent light-induced polar orientation via all-optical poling and photothermal cross-linking in a polymer thin film

An epoxy-based crosslinkable polymer functionalized with nonlinear optical (NLO) photochromic dye known as Red Acid Magly was polarly oriented via thermally-assisted all-optical poling to enhance the photostability of the induced order. During the writing (seeding) process the film was cross-linked by heating with a hot-plate and irradiated simultaneously by the coherent superposition of the 1.06 μm fundamental and 0.532 μm second harmonic beams of a nanosecond pulsed Nd:YAG laser. We demonstrate that crosslinking between the polymer matrix and the pendant chromophore groups induced during the thermally-assisted all-optical poling procedure results in a stable light-induced second order susceptibility.     

On the orientation independence of inverse pulsed laser deposition

Carbon nitride films have been deposited in the inverse pulsed laser deposition (IPLD) geometry by ablating a graphite target in nitrogen atmosphere while the spatial orientation of the target (and substrate) normal was varied. Two different orientations were tested, in one of which the axis of the plasma plume was made to point downwards, imposing the maximum gravitational barrier on the ablated species and make them move against the gravitational field while growing the film in order to verify the extent of a possible orientational effect. The thickness distribution of films obtained in different orientations was sampled along their axes of symmetry by stylus profilometry. The results indirectly proved that the kinetic energy of the species responsible for building the IPLD films surpassed the effect of gravitational field, even in the outer regions of the films, where the ablated species were believed to be thermalised. Evidences are also provided that utmost care should be taken to keep experimental conditions, like process pressure, spot size, etc., constant in order to get reproducible results.     

Polarizabilities and dipole moments of benzaldehyde, benzoic acid and oxalic acid in polar and nonpolar solvents

The purpose of this report is to calculate the orientation polarizability of benzaldehyde, benzoic acid and oxalic acid in polar and nonpolar solvents. The calculations are based on the knowledge of permanent dipole moment of the solutions. Other important physical quantities such as refractive index, density, specific volume, dielectric constant, molar polarization and molar refractivity are also calculated. Dipole moments of the solutions are calculated by using measured dielectric constants of the solutions. The dielectric constant measurements were made at 100 kHz. Relationships between the polarizability and concentration, specific volume, dielectric constant and dipole moment of the solutions are suggested.     

Opto-thermal behavior of polypropylene fibres using a modified hot-stage attached to the interference microscope

The influence of temperature on the optical and structural properties of three samples of polypropylene fibres (having different deniers) has been studied over the temperature range (28–67^oC). A hot-stage attached with the Pluta microscope has been modified for this purpose. The effect of temperature on the refractive indices (n, n), the mean polarizabilities per unit volume (P^ll, P) and the optical orientation function f(θ) have been investigated for each sample. The thermal coefficients of the refractive indices were determined. The refractive index profiles are also provided at different temperatures for each of the three tested samples. Microinterferograms are given for illustration.     

傅里叶变换红外偏振光谱在涤纶工业丝结构表征中的应用

应用傅里叶变换红外偏振光谱对涤纶工业丝样品的反式构象含量、非晶取向、整体取向等结构参数进行了表征，对制备涤纶工业丝各阶段中结构变化规律进行了初步探索。     

Orientation averaged angular distributions of photo-electrons from free Na clusters

We explore, from a theoretical perspective, photo-electron angular distributions (PAD) of small Na clusters using the time-dependent local-density approximation (TDLDA). We assume an isotropic ensemble of free clusters and develop, for the case of one-photon emission, analytical formulae for the orientation averaged PAD which require only six TDLDA calculations in properly chosen reference frames. All information in the averaged PAD is contained in one anisotropy parameter. This parameter varies little with system size, but is crucially influenced by the detailed ionic structure.     

温度对氨基苯甲酸在粗糙银表面上行为的影响

本文同时测定了当温度从－１９０℃上升到３０℃和从３０℃下降到－１９０℃对氨基苯甲酸（ｐ－Ａｍｉｎｏｂｅｎｚｏｉｃ Ａｃｉｄ，ＰＡＢＡ）和邻氨基苯甲酸（ｏ－Ａｍｉｎｄｂｅｎｚｏｉｎ Ａｃｉｄ，ＯＡＢＡ）在粗糙的银表面上的表面增强拉曼光谱的变化。结果表明，若吸附质表面拉曼光谱的增强主要表现为化学机理，且整个分子平躺在表面，则分子在表面上的取向不会随温度的变化而改变。而温度的变化会引起基于电磁场增强机理     

Research on growth and self-frequency doubling OF Nd:ReCOB (Re=Y OR Gd) crystals

Large (up to 45mm in diameter and 50mm in length) ReCa₄O(BO₃)₃ (ReCOB) and Nd:ReCOB (Re=Y or Gd) crystals with high optical quality were grown by well designed procedures. Crystal orientation was carefully determined. Based on the measurements of refractive indices the phase matching (PM) figures for both crystals were calculated. Theoretical calculation of the spatial distribution of the effective nonlinear coefficients, which show an asymmetric feature, was carried out to determine the optimal PM orientations which were experimentally confirmed, i.e. (66.3°, 134.4°) and (64.5°, 33.5°) for GdCOB and YCOB respectively.     

Degree complete graphs

Ryser [Combinatorial Mathematics, Carus Mathematical Monograph, vol. 14, Wiley, New York, 1963] introduced a partially ordered relation ‘?’ on the nonnegative integral vectors. It is clear that if S=(s₁,s₂,…,s_n) is an out-degree vector of an orientation of a graph G with vertices 1,2,…,n, then

(Π)