含8－羟基喹啉和噁二唑发光材料的合成与表征

本论文以提高有机／聚合物电致发光材料的发光效率为目的，通过改善发光材料分子的载流子传输平衡、增大分子体积为手段来减小荧光淬灭，设计并合成了一系列新型结构的络合物和聚合物。发现了一种合成五配位8-轻基喳琳铝络合物和双核铝8-轻基喳琳络合物的新方法，在分子中引入了电子和空穴传输基团改善了分子的载流子传输平衡，设计并合成了新型大体积的分子，提高了材料的发光效率，并系统地研究了分子结构与发光波长和发光效率的关系。主要工作如下：1发现了一种合成五配位8-经基喳琳铝络合物和双核铝8-经基喳琳络合物的新方法，克服了没有2一甲基的空间位阻作用很难形成五配位8-轻基喳琳铝络合物的困难。2合成了五配位2-甲基-8-轻基喳琳铝络合物并引入了具有不同空穴传输能力的第二配体。结果表明，与A 1 q;,相比，2-甲基-8-经基喳琳的引入导致了五配位络合物发光的蓝移，同时具有空穴传输能力的三苯胺基团的引入使电致发光器件的效率降低。3设计并合成了五配位8-轻基喳琳铝络合物，同时与Alq做了对比研究。研究发现，这一系列五配位络合物发射绿色荧光，五配位8-轻基喳琳铝络合物的发光波长主要由第一配体决定。4以五配位2-甲基-8-轻基喳琳铝和五配位8-轻基喳琳铝络合物为发光层制备了双层器件。结果表明，五配位8-经基喳琳铝络合物的电致发光波长主要由第一配体决定，第二配体只起到微弱的调节作用；第一配体对器件的发光效率起决定性的作用，第二配体的结构对络合物器件发光效率的影响在同一系列络合物中表现得非常明显。5从增加分子体积能够减小分子之间聚集，增强荧光效率这一观点出发，合成了具有双核铝的8一TTA-基喳琳络合物Me-DAlqz和PPv-DAlq3,用Me-DAlq,作发光层制备了双层器件，并与Alq_3i和AIMq_3作了对比研究。结果表明，DA 1 q,双层器件中的发光效率比Alq_3器件的性能稍高一些，证明了大体积分子能够增加荧光效率的观点。6合成了含有空穴传输性能的三苯胺基团的嗯二吟配体，并用其合 成了金属络合物。这些络合物发射蓝色的荧光，与不带三苯胺的德二哇金属络合物在溶液中发基本相同波长的荧光。但在薄膜和单层电致发光器件中，络合物的荧光发生了不同程度的红移。含三苯胺络合物的单层器件发光效率高于不含三苯胺络合物的单层器件的效率，证实了三苯胺的引入改进了载流子的传输平衡。7合成了系列嗯二哇基团两侧带有蔡环的金属络合物并以这些络合物为发光层制备了双层有机电致发光器件。结果表明，蔡环的引入导致了嗯二哇金属络合物在薄膜状态和电致发光器件中的发光波长比在溶液中的发光波长有了很大的红移。8设计并合成了既具有空穴传输性能又具有电子传输性能的蓝色发光聚合物。用电化学方法证明了它们具有两极性质，表明嗯二哇的引入增加了聚合物的电子传输能力。

Absorption spectra of Se-8-ring clusters in zeolite 5A

Samples with different weight ratio of Se to zeolite 5A (Se concentration) have been prepared by loading Se into the pores of zeolite 5A, and the measuerments of the absorption and Raman spectra have been carried out for the prepared samples. The measured absorption edges of the samples are close to the value for monoclinic Se containing Se-8-ring, suggesting the formation of Se-8-ring clusters(1) in the pores. The continuous and broadening features of the absorption spectra are interpreted by the strong electron-nucleus coupling in the Se-8-ring cluster. The absorption edges are red shifted with the increase of the Se concentration. It is tentatively attributed to two reasons. One is the existence of the double Se-8-ring cluster in the high Se concentration samples, and the other is that for the strong electron-nucleus coupling cluster, the absorption edge of the clusters system will be red shifted with the increase of the cluster concentration in the clusters system. A single broad band at about 262 cm(-1) is observed in the Raman spectra, which further supports the formation of Se-8-ring clusters. (C) 1997 Published by Elsevier Science S.A.

Long period two-dimensional gratings for 8-12 mu m quantum well infrared photodetectors

By considering all possible high order diffracted waves, the authors investigate the spectral response of two-dimensional gratings for quantum well infrared photodetectors (QWIPs). A new method is proposed that using long period gratings may improve grating quality and reduce the resulting cross talk in grating-coupled QWIPs. A sensitivity analysis indicates that the influence of variation of the grating constant on the coupling efficiency is less sensitive for the long period gratings than for the short ones. A large coupling efficiency has been demonstrated for long period gratings. The calculated wide grating response spectra are in good agreement with the experiment result. (C) 1996 American Institute of Physics.

Absorption and Raman spectra of Se-8-ring clusters in zeolite 5A

Samples with different weight ratio of Se to zeolite 5A (Se composition) have been prepared by loading Se into the cages of zeolite 5A and the measurements of the absorption and Raman spectra have been carried out for the prepared samples. The measured absorption edges of the samples close and blue shifted to the value for monoclinic Se containing Se-8-ring, suggesting the formation of Se-8-ring clusters dagger in the cages. The continuous and broadening features of the absorption spectra are interpreted by the strong electron-phonon coupling in Se-8-ring clusters. The sample with high Se composition has a red shift of the absorption band edge relative to the samples with less Se composition. It is tentatively attributed to the reason that with different Se composition, single Se-8-ring clusters and double Se-8-ring clusters are formed in the cages of zeolite 5A. A single broad band at about 262 cm(-1) is observed in the Raman spectra, that gives the further support of the formation of Se-8-ring clusters. Copyright (C) 1996 Elsevier Science Ltd

In0.2 Ga0.8 As-GaAs复合应力缓冲层上的1.3 μmInAs/GaAs自组织量子点

用光荧光谱和原子力显微镜测试技术系统研究了在2 nm In0.2Ga0.8As和x ML GaAs的复合应力缓冲层上生长的InAs/GaAs自组织量子点的发光特性和表面形貌.采用In0.2Ga0.8As与薄层GaAs复合的应力缓冲层,由于减少了晶格失配度致使量子点密度从约1.7×109 cm-2显著增加到约3.8×109cm-2.同时,复合层也有利于提高量子点中In的组份,使量子点的高宽比增加,促进量子点发光峰红移.对于x=10 ML的样品室温下基态发光峰达到1350 nm.

7.8μm二级分布反馈量子级联激光器

报道了基于应变补偿的InP基In0.53+xGa0.47-xAs/In0.52-yAl0.48+yAs分布反馈量子级联激光器.采用二级光栅作为反馈,激射工作波长为7.8μm,在1%占空比,5kHz频率的工作条件下,在93～173K的温度范围内,单模发射光谱边模抑制比均超过20dB,调谐系数dλ/dT=0.5125nm/K.在93K时,峰值功率为30mW,直到153K时,峰值光功率仍达到12mW.

赝配GaAs/In_(0.2)Ga_(0.8)As量子阱导带不连续量的C-V和电容瞬态测量

半导体材料开放实验室基金,国家自然科学基金

Surface Emitting Distributed Feedback Quantum Cascade Laser around 8.3 mu m

We demonstrate surface emitting distributed feedback quantum cascade lasers emitting at wavelengths from 8.1 mu m at 90 K to 8.4 mu m at 210 K. The second-order metalized grating is carefully designed using a modified coupled-mode theory and fabricated by contact lithography. The devices show single mode behavior with a side mode suppression ratio above 18 dB at all working temperatures. At 90 K, the device emits an optical power of 101 mW from the surface and 199 mW from the edge. In addition, a double-lobe far-field pattern with a separation of 2.2 degrees is obtained in the direction along the waveguide.

Effects of oriented substrates on cell morphology, the cell cycle, and the cytoskeleton in Ros 17/2.8 cells

Absence of gravity or microgravity influences the cellular functions of bone forming osteoblasts. The underlying mechanism, however, of cellular sensing and responding to the gravity vector is poorly understood. This work quantified the impact of vector-directional gravity on the biological responses of Ros 17/2.8 cells grown on upward-, downward- or edge-on-oriented substrates. Cell morphology and nuclear translocation, cell proliferation and the cell cycle, and cytoskeletal reorganization were found to vary significantly in the three orientations. All of the responses were duration-dependent. These results provide a new insight into understanding how osteoblasts respond to static vector-directional gravity.