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91.
在玻璃衬底上制得单层硬脂酸的Langmuir-Blodgett(LB)膜,做为4-戊基-4''-氰基联苯(5CB)液晶的取向层,在取向层上旋涂一层5CB液晶,用透射二次谐波方法测量出5CB液晶分子二阶非线性光学极化率,其值为β=7×10-29esu.对比文献值,测量得到的结果符合较好. 相似文献
92.
YANG Shengli CHEN Mouzhi 《Chinese Journal of Lasers》2002,11(1):23-26
1 Introduction Severalbiaxialcrystals ,suchasKTP ,LBO ,havesomeexcellentproperties,suchaslargenonlinear (NL )coefficients,widewavelengthrangesoftransmission ,andeasilygrowinglargesizecrystalwithhighquality .Thebiaxialcrystalshavebeenextensivelyusedinlaserfr… 相似文献
93.
2,3-Bis-(3,4-dicarboxyphenylcarboxyethoxy)-4′-nitrostilbene dianhydride (4) was prepared and reacted with 1,4-phenylenediamine, 4,4′-oxydianiline, 4,4′-diaminobenzanilide and 4,4′-(hexafluoroisopropylidene)dianiline to yield novel polyimides 5-8 containing 2,3-dioxynitrostilbenyl groups as NLO-chromophores, which constituted parts of the polymer backbones. The resulting polyimides 5-8 were soluble in polar solvents such as acetone and DMF. Polymers 5-8 showed a thermal stability up to 300 °C in TGA thermograms with Tg values obtained from DSC thermograms in the range of 135-160 °C. The SHG coefficients (d33) of poled polymer films at the 1064 cm−1 fundamental wavelength were around 5.26 × 10−9 esu. The dipole alignment exhibited exceptionally high thermal stability even at 30 °C higher than Tg and there was no SHG decay below 170-190 °C due to the partial main chain character of polymer structure, which was acceptable for NLO device applications. 相似文献
94.
As one of the most primitive nonlinear optical phenomena, optical second harmonic genera-tion (SHG) has been investigated for half a century and it has become a very useful spectroscopic tool in the study of surface and interface[1—3]. It was theoretically shown that the SH signal cannot be generated in a centrosymmetric system. However, the generation of SH signal from the centro-symmetric molecules such as fullerene (C60) and CuPc has been detected[4—7]. In our recent ex-periments, an … 相似文献
95.
The crystal structure of [Mn(HIDA)2(H2O)2] (Tetragonal, P4¯21c (no.114), a = b = 8.10(2)Å, c = 9.605(3)Å, α = β = γ = 90°, Z = 2, R = 0.051, wR2 = 0.123 for 460 observed reflections) consists of infinite acentric 2D square grids with HIDA— ions as bridging ligands. The 2D grids are interlocked(along the c axis) by hydrogen bonding. The Mn atoms are octahedrally coordinated by four O atoms of four HIDA— ions (d(Mn—O)= 2.183(4)Å ) and two O atoms of two water molecules (d(Mn—OW) = 2.154(5)Å ). The results show that this acentric coordination polymer exhibits strong powder second harmonic generation (SHG) efficiency, ca. 1.9 times that of potassium dihydrogen phosphate, and remarkable thermal stability. 相似文献
96.
2,4-Di-2′-hydroxyethoxy)benzylidenemalononitrile (3) was prepared and condensed with 2,4-toluenediisocyanate and 3,3′-dimethoxy-4,4′-biphenylenediisocyanate to yield unprecedented novel Y-type polyurethanes (4-5) containing 2,4-dioxybenzylidenemalononitrile group as a nonlinear optical (NLO) chromophore, which constitutes a part of the polymer backbone. The resulting polyurethanes 4-5 were soluble in common organic solvents such as acetone and DMF. Polymers 4-5 showed a thermal stability up to 260 °C from thermogravimetric analysis (TGA) with differential scanning calorimetry (DSC) giving Tg values around 143-156 °C. The approximate lengths of aligned NLO-chromophores estimated from AFM images of poled polymer films were about 10 nm. The SHG coefficients (d33) of poled polymer films were around 7.4 × 10−9 esu. These Poled polymers exhibited a greater thermal stability of dipole alignment even at 10 °C higher than Tg, and no SHG decay was observed below 155 °C due to the partial main chain character of the polymer structure and extensive hydrogen bonds between urethane linkage, which is acceptable for NLO device applications. 相似文献
97.
A new lithium zinc iodate, LiZnO(IO3), has been prepared by hydrothermal reactions at 200 °C. Single-crystal X-ray diffraction experiment revealed that the compound crystallizes in a noncentrosymmetric orthorhombic space group Ama2 with cell parameters: a = 6.3386(6) Å, b = 11.2613(11) Å, c = 4.6840(5) Å, Z = 4. In the structure, the basic building units are the distorted ZnO6 octahedron, LiO4 tetrahedron and the IO3 group. These groups are linked together to form a three-dimensional structure by sharing the oxygen atoms. The DSC measurement demonstrates that the compound is stable up to 490 °C. Powder second-harmonic generation (SHG) test shows that the SHG effect is about 2 × KH2PO4. 相似文献
98.
Raúl Mariaca Norwid-Rasmus Behrnd Fabien Helbling Gaëtan Couderc Helen Stoeckli-Evans 《Journal of fluorine chemistry》2009,130(2):175-20379
The syntheses and crystal structures of a series of fluoro-substituted halogeno (Cl, Br, I)-cyano-stilbenes containing donor and acceptor groups (D-π-A) are reported. These molecules show a tendency to form antiparallel chain-like structures and herringbone packing, crystallising predominantly in a centric space group. However, second harmonic generation measurements bear evidence for orientational disorder leading to partial polar order below the ordinary X-ray structure determination limit. Some co-crystals are isostructural with their components. The non-fluoro as well as the halogeno-fluoro substituted components of co-crystals seem to impose their crystal structure on the complementary fluoro- or cyano-fluoro substituted components. Co-crystallization enhanced the deviation from centrosymmetry. 相似文献
99.
L. Y. Zhu D. Xu X. Q. Wang X. J. Liu G. H. Zhang J. Sun 《Crystal Research and Technology》2006,41(12):1226-1230
Bis(isothiocyanato)‐bis(4‐methylpyridine)zinc(II)(Zn(SCN)2(C6H7N)2), (abbreviated as ZBNC) single crystals of optical quality have been grown from acetone solution by the slow temperature‐lowering method. Its solubilities at different temperatures in acetone were measured. The X‐ray powder diffraction (XRPD) spectroscopy of ZBNC crystal was performed at room temperature. The second harmonic generation (SHG) efficiency was determined by powder technique of Kurtz and Perry using Nd:YAG laser, which is equivalent to KDP crystal. The thermal decomposition process was characterized by thermal gravity and differential thermal analysis (TG\DTA). The specific heat of the crystal is 1440.67 J/mol·K at 325 K. The IR spectrum was recorded in the 500∼3500 cm–1 region, using KBr pellets on a Nicolet 170sx FT‐IR spectrometer. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
100.
Prof. Hongping Wu Dr. Bingbing Zhang Hongwei Yu Zhanggui Hu Jiyang Wang Yicheng Wu Prof. P. Shiv Halasyamani 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(23):9007-9011
Discovering new deep-ultraviolet (DUV) nonlinear optical (NLO) materials is currently a great challenge. The reported DUV NLO materials are almost exclusively borates or phosphates. Silicates—the largest constituent of the earth's crust—are excluded owing to their weak second harmonic generation (SHG) response. We report a silicate, Li2BaSiO4, with edge-sharing LiO4–SiO4 tetrahedra that achieves the balance between a short UV absorption edge, below 190 nm, and a large SHG response, 2.8×KDP. The SHG intensity is the largest for silicates without second-order Jahn–Teller cations, and exceeds that of non-isomorphic Li2SrSiO4 by more than an order of magnitude. As such Li2BaSiO4 may be seen as a promising DUV-UV NLO material. This research indicates that edge-sharing tetrahedra is a new design parameter for discovering new DUV NLO materials. 相似文献