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251.
本文合成了一种新型的两亲性酞菁分子,研究了它在不同溶剂中的聚集行为,考察了酞菁及酞菁与正十六烷混合的成膜性能,制备了混合的多层LB膜,并利用紫外光谱研究LB膜内的分子聚集状况,用分子激子理论对实验结果加以分析,还应用偏振紫外的方法对LB膜内酞菁分子大环的取向进行了确定。 相似文献
252.
简要介绍了夸克的发现、核子的夸克模型 ,详细讨论了夸克模型中核子内夸克自旋结构和极化轻子-核子深度非弹散射测量出的夸克自旋结构中的矛盾 .指出这个矛盾是由于对夸克自旋理解的混淆.最后还讨论了规范不变性和正则量子化两大物理学原则在夸克、电子轨道角动量上出现的矛盾. A simple introduction of the discovery of quark and the constituent quark model of nucleon have been given. The contradiction between the quark spin structure of nucleon of the constituent quark model and the measured one in the polarized deep inelastic lepton nucleon scattering has been explained in detail. It is elucidated that the so called “proton spin crisis” is due to quark spin confusion. The incompatibility between the requirement of gauge invariance and ... 相似文献
253.
非晶态分子合金低温制备纳米复合氧化物La~1~-~xCa~xMnO~3 总被引:1,自引:0,他引:1
钙钛矿型稀土锰氧化物La~1~-~xCa~xMnO~3(RE=La,Pr,Nd,Gd;T=Ca,Sr,Ba,Pb等)因其特殊的巨磁电阻效应,引起人们广泛的关注。用非晶态的分子合金为前驱体,制备了一系列具有纳米尺寸的La-Ca-Mn-O复合氧化物颗粒。研究表明,前驱体的晶化温度对纳米颗粒的形貌和大小均有影响。当晶化温度为450℃-600℃时,从透射电子显微镜观察到的颗粒大小约为25nm-100nm。该纳米材料的磁及磁电阻行为不同于其体相体系,其交流磁化率表现出较较强的尺寸依赖性,而磁电阻具有本征型和自旋隧穿型的巨磁电阻行为。 相似文献
254.
255.
Atsushi Okamoto Hisashi Matsuoka Motoki Saito Yoshihisa Takayama Mototsugu Takamura 《Optical Review》1999,6(3):189-195
We propose a new optical network device photorefractive connection module (PRCM) which operates as optical switch, amplifier and signal distributor controlled by parallel optical signals. Simple optical control bus systems can be realized by cascade connection of PRCMs. PRCM branches off a desired channel from the spatial multiplexed optical bus line by appropriate setting of the control beam pattern. PRCM uses cross polarized four wave mixing (CPFWM) with extraordinary polarized writing beams and an ordinary polarized reading beam to achieve a high connection gain to the next PRCM stage. We analyze the phase matching angle of CPFWM in which the optical paths of two pump beams are slightly different. The phase conjugate reflectivity indicating a branching ratio of optical signal is derived and calculated in consideration of the phase mismatching Δk. The optimum pump ratio and the grating vector orientation for the largest phase conjugate reflectivity and signal amplification factor are discussed for optical design of PRCM. Since the measured signal beam power after passing through the BaTiO3 crystal is three or four times higher than its incident power, PRCM has a sufficient connection gain for optical bus and interconnection systems. 相似文献
256.
257.
Daichi Okada Fumito Araoka 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2024,136(21):e202402081
The chiral organic–inorganic halide perovskites (OIHPs) are vital candidates for superior nonlinear optical (NLO) effects associated with circularly polarized (CP) light. NLO in chiral materials often couples with magnetic dipole (MD) transition, as well as the conventional electric dipole (ED) transition. However, the importance of MD transition in NLO process of chiral OIHPs has not yet been well recognized. Here, the circular polarized probe analysis of second harmonic generation circular dichroism (SHG-CD) provides the direct evidence that the contribution of MD leads to a large anisotropic response to CP lights in chiral OIHPs, (R-/S-MBACl)2PbI4. The thin films exhibit great sensitivity to CP lights over a wide wavelength range, and the g-value reaches up to 1.57 at the wavelength where the contribution of MD is maximized. Furthermore, it is also effective as CP light generator, outputting CP-SHG with maximum g-factor of 1.76 upon the stimulation of linearly polarized light. This study deepens the understanding of relation between chirality and magneto-optical effect, and such an efficient discrimination and generation of CP light signal is highly applicable for chirality-based sensor and optical communication devices. 相似文献
258.
Liquid crystalline materials display unique properties which can be exploited in organic light-emitting diodes. Characteristic features of liquid crystals are the anisotropy of electronic properties, a strong coupling to external fields as well as a tendency to form spontaneously homogeneous monodomain films. It is found that liquid crystalline materials can be used in light-emitting diodes to control the state of polarization of the emitted light, the magnitude of the onset field for emission as well as the quantum efficiency. Both low molar mass and polymeric liquid crystals have been introduced with great success in single as well as in multilayer devices. © 1998 John Wiley & Sons, Ltd. 相似文献
259.
Minghe Li Wuli Yang Zhenxia Chen Ji Qian Changchun Wang Shoukuan Fu 《Journal of polymer science. Part A, Polymer chemistry》2006,44(20):5887-5897
A group of polymerizable amphiphiles, with their critical packing parameters systematically varied, were studied with respect to the phase behavior and immobilization of their lyotropic liquid‐crystalline phase structures. Small‐angle X‐ray scattering and polarized light microscopy were used to study their liquid‐crystalline phases before and after photopolymerization. The liquid crystallinity of the amphiphiles depended on the contents of both oil and water in the ternary systems. Through photopolymerization, hexagonal phases could generally be immobilized, with the structural order reduced to various degrees. However, the cubic phases evolved with polymerization into another structural pattern, which was possibly related to the lamellar structure. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5887–5897, 2006 相似文献
260.