树枝状电光材料研究进展

电光材料是以光子为载体的新一代信息材料. 目前, 研究的焦点主要集中在树枝状电光材料. 综述了近几年树枝状电光材料的研究进展, 主要包括树枝状电光大分子、树枝状电光高分子以及超分子自组装电光聚合物.     

电光高分子材料的最新研究进展

电光高分子材料由于其在光电子信息领域的潜在应用前景已得到了广泛关注和深入研究.本文在简要介绍电光效应及其材料等相关知识的基础上,综述了最近几年来电光高分子材料的研究进展,主要包括生色团的设计与合成,以及掺杂型、侧链型、主链型、交联型、互穿网络型和树枝型等聚合物材料体系的设计与合成.     

电光高分子研究进展

电光高分子是二阶非线性光学材料的重要组成部分,目前的研究重点主要在于合成具有高二阶非线性光学效应和取向稳定性以及低光学损耗的电光高分子,以满足高性能光学器件的制作要求。最近,电光高分子的设计与合成已经取得了很大的进展,例如结合"位分离"原理,利用高分子良好的加工性,获得了一些具有较好综合性能的高分子,可以较为有效地将小分子发色团的高β值转换为高分子大的宏观电光效应。本文综述了近几年来电光高分子的研究进展,主要包括线型电光高分子、树枝状电光高分子和超支化高分子。     

环氧树脂基高分子分散液晶材料相分离过程的研究

根据高分子分散液晶材料在相分离过程中透光率的变化,研究了高分子分散液晶材料相分离过程与液晶浓度、温度的关系,观察到相分离过程中的周期性的起伏现象．对相分离过程与高分子分散液晶材料的电光性能作了初步探讨     

液晶／高分子复合显示材料研究进展

综述了近年来液晶／高分子复合电光显示材料的研究进展。概括了液晶高分子复合膜显示材料的最新研究成果，就材料的制备方法、性能和应用前景等方面进行了探讨。     

輻射聚合反应

利用高能輻射引发化学反应的研究,近十年来由于广泛应用强辐射源(核反应堆、放射性同位素、粒子加速器等)而有了迅速的发展,从而组成了一门新兴的科学——辐射化学。辐射化学在高分子化学中的应用主要有三个方面:高聚物的辐射改性;乙烯基类单体的辐射聚合以及单体-高聚物干鏈的辐射接枝等。这方面的研究是辐射化学发展中尤其迅速的一个方面,目     

辐射在医用高分子材料中的应用

本文介绍了在医学中应用的高分子材料概况和对材料的特殊要求,以及用辐射法制造此类材料的一般途径、方法和优点,并对一些生物活性物质在高分子材料上的辐射固着化方面的研究成果、实际应用和发展前景进行了讨论。     

高分子材料的微波辅助合成研究进展

微波加热以其省时、高效、清洁环保的显著优势而使微波辅助合成成为一种广受欢迎的合成技术。高分子材料的传统合成反应时间长、耗能大。将微波辐射应用于高分子材料的合成可缩短反应时间、降低反应能耗,已成为有机合成领域的研究热点。本文简要综述了微波辅助合成技术在工程材料高分子聚酰胺、聚酰亚胺、聚丙烯酸苄基酯以及在医用功能高分子、吸附功能高分子、导电功能高分子和光学功能高分子合成中的研究进展,并展望了微波辅助合成在高分子材料合成中的发展前景。     

木质素先进材料的研究进展

综述了木质素改善合成高分子材料的性能和制备光电材料、阻燃材料、电磁屏蔽材料等方面的研究进展。加强木质素结构和性能的基础研究,解决木质素反应活性偏低以及与基体相容性差的问题,将木质素的耐辐射、可生物降解、阻燃、电磁屏蔽等特异性能引入到传统合成高分子材料中,制备性能优异、功能多样的先进高分子材料,是木质素高值化利用的一个重要方向。     

一种光交联电光聚合物的合成及其外部电光测量

合成了一种新的带有光交联基团的电光聚合物,其高分子基体是双酚A环氧树脂,二阶非线性生色团对硝基苯胺和光交联基团肉桂酰氯都键接在高分子链上.将聚合物溶解后旋涂成膜,对薄膜进行电晕极化.极化的后阶段用紫外光照射,使聚合物体系交联成网络结构,形成生色团取向长时间稳定的聚合物电光薄膜.用这种聚合物电光薄膜构成外部电光调制系统,测量了共面波导上的电信号.     

Measurement of coherent terahertz radiation for time-domain spectroscopy and imaging

A high-power terahertz (THz) source for THz time-domain spectroscopy (THz-TDS) and THz imaging has been developed based on an S-band compact electron linac at the National Institute of Advanced Industrial Science and Technology (AIST). A THz pulse was generated as coherent synchrotron radiation (CSR) from an ultra-short electron bunch and expected to have peak power of kW-order with frequency range of 0.1–2 THz. The electro-optic (EO) sampling method with a ZnTe crystal for the THz pulse measurement has been prepared for THz-TDS system. The timing measurement between the THz pulse and a probe laser was carried out. A preliminary experiment of THz transmission imaging of an integrated circuit (IC) card has been successfully demonstrated using the THz CSR pulse and a W-band rf detector. The imaging result was experimentally compared with a result of X-ray imaging. It is confirmed that its intensity and stability are enough to perform for the THz applications.     

New materials for optical rectification and electrooptic sampling of ultrashort pulses in the terahertz regime

The synthesis and nonlinear optical characterization of new electrooptic (EO) materials useful for terahertz (THz) applications is presented. Semiempirical calculations were used to guide the development of a series of chromophores on the basis of 2‐dicyanomethylen‐3‐cyano‐4,5,5‐trimethyl‐2,5‐dihydrofuran acceptors acting as guests in polymer films used in the generation of THz radiation via optical rectification. Amorphous films, 65–250 μm thick, with EO coefficients as high as 52 pm/V at 785 nm were used to generate sub‐picosecond pulses with bandwidths up to 3 THz. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2492–2500, 2003     

Non-invasive single bunch monitoring for ps pulse radiolysis

A single-shot electro-optic (EO) diagnostic has been installed on the ELYSE photocathode RF gun accelerator to monitor the electron bunch at the place and under the conditions of the ps pulse radiolysis experiments. The EO signal is due to the coulombic field of the electron bunch and to a contribution of a free-space THz radiation generated by the same electron pulse. This signal is recorded shot-to-shot at the repetition rate of the accelerator. The jitter of the arrival time of the electron bunch is characterized for the first time with a non-invasive method and is confirmed to be around 1 ps.     

Collective dynamics of lysozyme in water: terahertz absorption spectroscopy and comparison with theory

To directly measure the low-frequency vibrational modes of proteins in biologically relevant water environment rather than previously explored dry or slightly hydrated phase, we have developed a broadband terahertz spectrometer suitable for strongly attenuating protein solutions. Radiation is provided by harmonic multipliers (up to 0.21 THz), a Gunn oscillator (at 0.139 THz), and the UCSB free-electron lasers (up to 4.8 THz). Our spectrometer combines these intense sources with a sensitive cryogenic detector and a variable path length sample cell to detect radiation after it is attenuated by more than 7 orders of magnitudes by the aqueous sample. Using this spectrometer, we have measured the molar extinction of solvated lysozyme between 0.075 and 3.72 THz (2.5-124 cm(-1)), and we made direct comparison to several published theoretical models based on molecular dynamics simulations and normal-mode analysis. We confirm the existence of dense, overlapping normal modes in the terahertz frequency range. Our observed spectrum, while in rough qualitative agreement with these models, differs in detail. Further, we observe a low-frequency cutoff in terahertz dynamics between 0.2 and 0.3 THz, and we see no evidence of a predicted normal mode at approximately 0.09 THz for the protein.     

Terahertz time-domain spectroscopy as a novel tool for crystallographic analysis in cellulose: the potentiality of being a new standard for evaluating crystallinity

Cellulose - Given that terahertz (THz) radiation responds to intermolecular forces such as hydrogen bonds, THz time-domain spectroscopy (THz-TDS) has expanded possibilities in cellulose research....     

Synthesis of novel polyarylate with elecrooptical chromophores as side chain as electro-optic host polymer

Two novel soluble polyarylates with different nonlinear optical chromophores as the side chains were prepared and characterized by UV–visible spectra, nuclear magnetic resonance, and infrared spectroscopy. The titled polymers show us good thermal stability; the thermal decomposition temperature values were 201 and 253?°C, respectively, for polymer sPAR-CTCF and sPAR-CTCP. The glass transition temperatures were 139 and 122?°C for sPAR-CTCF and sPAR-CTCP, respectively. Chromophore FTC-wl was doped in these polymers as a guest chromophore to form binary chromophore electro-optic (EO) system. And super large EO coefficients (124?pm/V) were found from FTC-wl-doped sPAR-CTCP binary chromophore system at high chromophore loading density.     

Angle-dependent terahertz time-domain spectroscopy of amino acid single crystals

The measurement of absorption spectra using angle-dependent terahertz (THz) time-domain spectroscopy for amino acid single crystals of l-cysteine and l-histidine is reported for the first time. Linearly polarized THz radiation enables us to observe angle-dependent far-infrared absorption spectra of amino acid single crystals and determine the direction of the oscillating dipole of the molecules in the 20-100 cm(-1) range. By comparing the THz spectra of a single crystal and powder, we found that there was a clear hydrogen-bond peak in the crystal spectrum as a result of the larger hydrogen-bond network. The low-temperature THz spectra of amino acid microcrystals showed more intermolecular vibrational modes than those measured at room temperature. An ab initio frequency calculation of a single amino acid molecule was used to predict the intramolecular vibrational modes. The validity of the calculation models was confirmed by comparing the results with experimentally obtained data in the Raman spectral region.     

Preparation and characterization of the soluble NLO polyarylates with enhanced electro-optic properties

Three novel nonlinear optical polyarylate polymers were prepared containing one main-chain polymer (mPAR-chr1) and two side-chain polymers (sPAR-chr1, sPAR-chr2) with different kinds of chromophores. The obtained polymers were characterized and evaluated by UV-Vis, ¹H NMR, DSC and TGA. All the polymers exhibited excellent thermal stability, film forming ability and good electro-optic (EO) activity. The relationship between EO coefficients (r ₃₃) and the chromophore concentration of the three polymers had been also characterized and discussed. There were no obvious differences found in EO activity between main-chain and side-chain polyarylates with the same chromophore (chr1). Due to the stronger electron-withdrawing tricyanopyrroline acceptor and the steric effect of the large dendritic groups of chromophore 2 (chr2), polymer sPAR-chr2 showed the largest EO cofficients (64 pm V^?1) in these new polymers.     

太赫兹时域光谱技术在化学领域中应用的新进展

随着超快激光技术的发展及其人们对太赫兹(THz)电磁波波段及与脉冲光源认识的进一步深入,太赫兹时域光谱(THz-TDS)技术作为一种新的、快速发展的光谱分析方法在许多领域备受关注。尤其在化学领域,THz-TDS技术已得到了广泛的应用,并显示出了广阔的应用前景。本文介绍了THz技术的特点、THz辐射的产生、探测及其信号处理;讨论了该技术在化学及其相关领域中的应用;初步探讨了该技术在化学领域应用中一些亟待解决的问题及今后发展的方向。     

Optimizing terahertz emission from double quantum wells

The terahertz (THz) radiation emitted from a double quantum well is investigated and optimized. Exploiting the phenomenon of quantum stochastic resonance (whereby the oscillation amplitude of a dissipative two-level system exhibits at low temperatures a non-monotonic response with respect to the parameters of a monochromatic external field or the strength of dissipation) to drive a series of identical double quantum wells, it is shown that the coherence properties of the emitted THz radiation can be boosted significantly.