有机二阶非线性光学分子设计和合成研究进展

从分子工程的角度简述了有机二阶非线性光学分子的设计原则,对尿素衍生物,间二取代苯衍射生物,芳香硝基化合物,有机盐,芳发环化合物,含偶氮基团化合物,金属有机化物合物等有机二阶非线性光学分子的设计,合成,性能与结构特点进行了评述。     

新型双羟乙氨基硝基型偶氮分子的合成、光学非线性和热稳定性

设计和合成了2种双羟乙氨基给体和硝基受体有效组合的新型偶氮分子,采用核磁共振、红外光谱、紫外光谱及熔点测定对化合物进行表征,研究化合物的热稳定性、线性和非线性光学性质.用熔致变色法测定这2种化合物的非线性极化率,分别为140×10-30esu 和351×10-30esu;热分解温度分别达到291.93 ℃和302.36 ℃,这2种非线性光学生色分子表现出较大的光学非线性和良好的热稳定性.     

有机光折变聚合物材料的研制(I)——4-(对硝基苯偶氮)-3-氯苯胺偶氮增感染料的合成

偶氮增感染料在以聚乙烯咔唑为主体的光折变材料复合物中起着十分重要的作用。为了进一步研究不同的偶氮增感染料对光折变性能的影响。我们合成了一些偶氮化合物,并对它们进行了结构表征。结果表明,偶联反应发生在间氯苯胺的对位上。     

含偶氮非线性光学生色团取代炔的合成及光限幅性能研究

合成一种新的偶氮苯非线性光学生色团取代乙炔,用红外光谱,元素分析,核磁共振对其进行了表征,利用波长1064nm脉冲宽度40ps的激光,对该化合物光学性能进行研究,结果显示该化合物的THF溶液对40ps的1064nm脉冲激光呈现出较好的光限幅性能,其限幅阈值为235.9GW cm2。     

有机光折变聚合物材料的研制(Ⅰ)--4-(对硝基苯偶氮)-3-氯苯胺偶氮增感染料的合成

偶氮增感染料在以聚乙烯咔唑为主体的光折变材料复合物中起着十分重要的作用.为了进一步研究不同的偶氮增感染料对光折变性能的影响.我们合成了一些偶氮化合物,并对它们进行了结构表征.结果表明,偶联反应发生在间氯苯胺的对位上.     

侧链含杂环偶氮结构聚合物的三阶非线性光学性能

合成了具非线性光学性能的杂环偶氮生色团的单体化合物甲基丙烯酸(4-苯并噻唑-2-偶氮基苯基)酯(BAMA),并通过自由基聚合得到均聚物聚甲基丙烯酸(4-苯并噻唑-2-偶氮基苯基)酯(PBAMA).利用1 H-NMR验证了聚合物的结构,采用Z-扫描法研究了聚合物溶液的三阶非线性光学性能.结果表明,单体和聚合物均具有较高的三阶非线性光学系数.     

有机光折变聚合物材料的研制（I）——4—（对硝基苯偶氮）—3—氯苯胺偶氮增感染料的合成

偶氮增感染料在以聚乙烯卡唑为主体的光折变材料复合物中起着十分重要的作用。为了进一步研究不同的偶氮增感染料对光折变性能的影响。我们合成了一些偶氮化合物，并对它们进行了结构表征。结果表明，偶联反应发生在间氯苯胺的对位上。     

3-甲基-4-硝基吡啶氧中甲基对二阶非线性光学性质的作用

研究了3-甲基4-硝基毗啶氧中甲基对二阶非线性光学性质和晶体结构的影响，用量子化学方法计算分析了标题化合物的电子和微观二阶非线性光学性质．结果表明甲基对分子内电荷转移和分子二阶非线性光学系数几乎没有影响，但它对材料的非中心对称的晶体结构起着决定性的作用，从而成为材料呈现很强的宏观二阶非线性光学性质的决定性基团．     

聚3-丁酰基吡咯偶氮苯甲烯的非线性光学性能

通过3 丁酰基吡咯单体与4 醛基4’ 二甲氨基偶氮苯的缩聚反应合成了一种侧链含偶氮基团的新型聚吡咯甲烯衍生物———聚[(3 丁酰基吡咯 2,5 二)对二甲氨基偶氮苯甲烯](PBPDMAABE).与无取代基的聚[(吡咯 2,5 二)对二甲氨基偶氮苯甲烯]相比,该聚合物的溶解及成膜性能得到了很大的改善.PBPD MAABE的分子结构通过氢核磁共振谱和红外光谱得到了确认.由聚合物紫外 可见吸收光谱测得其光学禁带宽度为1 82 eV.采用后向简并四波混频(DFWM)技术测试了聚合物溶液与薄膜的三阶非线性光学性能,其浓度为3 65×10-5 mol/L的氯仿溶液和薄膜的三阶非线性极化率分别为 2 12×10-8 esu和 3 91×10-8esu.通过理论计算可得 PBPDMAABE 的二阶超分子极化率和非线性折射率分别为 2 68×10-25 esu 和5 47×10-7 esu.实验结果表明,PBPDMAABE具有优良的非线性光学性能.     

一种水溶性偶氮聚电解质的合成及光响应性

为合成水溶性含偶氮基团的聚电解质 ,利用重氮化偶合反应 ,将羧基引入偶氮化合物中 ,合成了一种新型的水溶性偶氮化合物。用 1 H- NMR,IR和 UV- Vis证实了其结构。该化合物聚合后得到的聚电解质水溶液随着 p H值的变化 ,在紫外可见光谱图上的吸收强度和峰位置都发生显著地变化 ,表现出 p H值敏感性。该聚电解质同时具有良好的光响应性和自组装性。拓宽了含偶氮基团聚合物的应用范围     

A photorefractive organically modified silica glass with high optical gain

Photorefractive materials exhibit a spatial modulation of the refractive index due to redistribution of photogenerated charges in an optically nonlinear medium. As such, they have the ability to manipulate light and are potentially important for optical applications including image processing, optical storage, programmable optical interconnects and simulation of neural networks. Photorefractive materials are generally crystals, polymers and glasses with electro-optic or birefringent properties and noncentrosymmetric structure. Here we report the photorefractive effect in both non-centrosymmetric and centrosymmetric azo-dye-doped silica glasses, in which refractive index gratings that are spatially phase-shifted with respect to the incident light intensity pattern are observed. The effect results from a nonlocal response of the material to optical illumination, and enables the transfer of energy between two interfering light beams (asymmetric two-beam coupling). Although the writing time for the present grating is relatively slow, we have achieved a two-beam coupling optical gain of 188 cm(-1) in the centrosymmetric glasses, and a gain of 444 cm(-1) in the non-centrosymmetric structures. The latter are fabricated using a corona discharge process to induce a permanent arrangement of azo-dye chromophores.     

FKF1 is essential for photoperiodic-specific light signalling in Arabidopsis

Adaptation to seasonal change is a crucial component of an organism's survival strategy. To monitor seasonal variation, organisms have developed the capacity to measure day length (photoperiodism). Day-length assessment involves the photoperiodic control of flowering in Arabidopsis thaliana, whereby the coincidence of light and high expression of CONSTANS (CO) induces the expression of FLOWERING LOCUS T (FT), leading to flowering in long-day conditions. Although controlling CO expression is clearly a key step in day-length discrimination, the mechanism that generates day-length-dependent CO expression remains unknown. Here we show that the clock-controlled FLAVIN-BINDING, KELCH REPEAT, F-BOX (FKF1) protein has an essential role in generating the diurnal CO peak and that this function is dependent on light. We show that a recombinant FKF1 LIGHT, OXYGEN OR VOLTAGE (LOV) domain binds the chromophore flavin mononucleotide and undergoes light-induced photochemistry, indicating that FKF1 may function as a photoperiodic blue-light receptor. It is likely that the circadian control of FKF1 expression and the light regulation of FKF1 function coincide to control the daytime CO waveform precisely, which in turn is crucial for day-length discrimination by Arabidopsis.     

Threshold effect of incident light intensity on the photorefractive light-induced scattering in double-doped lithium niobate crystals and its application

The formation mechanism of fanning noise in lithium niobate crystal is theoretically studied using the multi-wave mixing model. The threshold effect of incident light intensity for the photorefractive light-induced scattering in double doped lithium niobate crystal is explained by combining the multi-wave mixing model with the rwo-photorefrac-tive-sensitive-center model for single charge-carrier. Light amplification competition between the fanning noise and the signal beam in doped lithium niobate crystals is also studied. The existence of optimum photovoltaic field and optimum pump intensity is predicted theoretically.     

a－Si：Hp－i－n型太阳能电池中的载流子俘获效应──a－Si：H太阳能电池稳定性研究

本文基于我们的实验结果，应用Ｓｃｈａｒｆｅｔｔｅｒ－Ｇｕｍｍｅｌ解法数值求解Ｐｏｉｓｓｏｎ方程，对经高强度光辐照过的ａ－Ｓｉ：ＨＰ－ｉ－ｎ型太阳能电池进行计算机数值分析。结果表明，随着光辐照发生的载流子俘获所造成的ａ－Ｓｉ：Ｈ中空间电荷净增加或减少都会使电池内部电场分布产生变化和准中性区（低场“死层”）的出现。这是ａ－Ｓｉ：Ｈｐ－ｉ－ｎ型太阳能电池光致性能衰退的重要原因。于是，一条提高ａ－Ｓｉ：Ｈ太阳能电池稳定性的新途径有可能被提出。     

Self-directed growth of molecular nanostructures on silicon

Advances in techniques for the nanoscale manipulation of matter are important for the realization of molecule-based miniature devices with new or advanced functions. A particularly promising approach involves the construction of hybrid organic-molecule/silicon devices. But challenges remain--both in the formation of nanostructures that will constitute the active parts of future devices, and in the construction of commensurately small connecting wires. Atom-by-atom crafting of structures with scanning tunnelling microscopes, although essential to fundamental advances, is too slow for any practical fabrication process; self-assembly approaches may permit rapid fabrication, but lack the ability to control growth location and shape. Furthermore, molecular diffusion on silicon is greatly inhibited, thereby presenting a problem for self-assembly techniques. Here we report an approach for fabricating nanoscale organic structures on silicon surfaces, employing minimal intervention by the tip of a scanning tunnelling microscope and a spontaneous self-directed chemical growth process. We demonstrate growth of straight molecular styrene lines--each composed of many organic molecules--and the crystalline silicon substrate determines both the orientation of the lines and the molecular spacing within these lines. This process should, in principle, allow parallel fabrication of identical complex functional structures.     

PVA、聚丙烯纤维和硅烷基粉末对隧道防火涂料性能的影响

在隧道防火涂料配方中加入聚乙烯醇(PVA)、聚丙烯纤维及硅烷基粉末进行改性,并进行宏观试验(粘结、耐火、抗渗和抗裂试验)和微观试验(孔结构、电镜扫描和热重分析试验)研究.试验结果表明:在隧道防火涂料中掺入适量的PVA、聚丙烯纤维和硅烷基粉末,可以优化孔结构、改善界面过渡区、使内部受力更均匀,从而提高隧道防火涂料的粘结强度、抗渗和抗裂性能.     

Light-driven monodirectional molecular rotor.

Attempts to fabricate mechanical devices on the molecular level have yielded analogues of rotors, gears, switches, shuttles, turnstiles and ratchets. Molecular motors, however, have not yet been made, even though they are common in biological systems. Rotary motion as such has been induced in interlocked systems and directly visualized for single molecules, but the controlled conversion of energy into unidirectional rotary motion has remained difficult to achieve. Here we report repetitive, monodirectional rotation around a central carbon-carbon double bond in a chiral, helical alkene, with each 360 degrees rotation involving four discrete isomerization steps activated by ultraviolet light or a change in the temperature of the system. We find that axial chirality and the presence of two chiral centres are essential for the observed monodirectional behaviour of the molecular motor. Two light-induced cis-trans isomerizations are each associated with a 180 degrees rotation around the carbon-carbon double bond and are each followed by thermally controlled helicity inversions, which effectively block reverse rotation and thus ensure that the four individual steps add up to one full rotation in one direction only. As the energy barriers of the helicity inversion steps can be adjusted by structural modifications, chiral alkenes based on our system may find use as basic components for 'molecular machinery' driven by light.     

掺氢非晶硅薄膜材料光稳定性的研究

用射频辉光放电法制备了a Si:H样品 ,并对样品进行了光照测试 实验表明 ,样品经过光照后 ,光电流和暗电流逐渐减小 ,在光照初期 ,这种变化很大 ,随着光照时间增加 ,光诱导效应渐趋饱和 ,这种现象是由于强光照产生亚稳缺陷态所引起 讨论了在非晶硅氢薄膜中亚稳光诱导变化的机理 ,并解释了S W效应形成的微观过程     

金属-染料包覆共掺杂复合物的制备与热学特性

提出了一种基于包覆共掺杂结构金属纳米粒子偶氮染料复合物(MNPADC) 合成的新方法,可使偶氮染料甲基橙定向吸附于球形金属银纳米粒子表面形成染料对纳米粒子的包覆结构,再将具有该结构的掺杂剂掺于聚合物基质聚乙烯醇中,制备出MNPADC复合材料薄膜.紫外可见吸收光谱表明,该材料在波长为400~450 nm的波段具有良好的光吸收特性.热质量分析发现,其热学特性更适合于光存储的要求.实验结果表明,该材料的设计方法为改善有机光存储介质材料的热学性能提供了简便而有效的途径.     

用第一性原理计算硅单空位缺陷

采用分子动力学模型及共轭梯度,并在局域密度挖下,用密度泛函的方法从头计算了硅单晶的晶格常数、单空位缺陷能等。计算结果表明,在硅单晶中,单空位邻近的硅原子会发一弛豫,使对称性下降;两个单空位有可能形成一个双空位。