Lasing behavior in DCM-doped PVK microcavity

A surface emitting microcavity was formed by sandwiching a polymer film containing PVK, Alq(3) and DCM between a distributed Bragg reflector (DBR) with a reflectivity of 99% and a silver film (300 nm). The lasing phenomenon was observed in DCM-doped PVK microcavity. The full width at half maximum (FWHM) was 0.6 nm with the peak wavelength at 603 nm. The threshold energy for lasing was estimated to be about 2.5 mu J per pulse. (C) 2000 Published by Elsevier Science S.A. All rights reserved.

Optimal feedback control of two-photon fluorescence based on genetic algorithm

An optimal feedback control of two-photon fluorescence in the ethanol solution of 4-dicyanomethylene-2-methyl-6-p-dimethyl-amiiiostryryl-4H-pyran (DCM) using pulse-shaping technique based on genetic algorithm is demonstrated experimentally. The two-photon fluorescence of the DCM ethanol solution is enhanced in intensity of about 23%. The second harmonic generation frequency-resolved optical gating (SHG-FROG) trace indicates that the effective population transfer arises from the positively chirped pulse. The experimental results appear the potential applications of coherent control to the complicated molecular system.

染料掺杂聚合物薄膜放大自发发射和受激发射的研究

随着有机／聚合物电致发光材料在有机发光二极管上的应用以及有机晶体管和有机太阳能电池的研制成功，有机／聚合物电致发光材料的优异的光电性能、低廉的生产成本、简单的加工工艺、宽广的选材范围和良好的机械性能等优点极大地吸引科学家们的研究兴趣，并开始了有机／聚合物发光薄膜的放大的自发发射和受激发射行为的研究。有机分子和聚合物的诸多如易得、廉价、结构多样、功能易调节、大的横截面积、高的荧光量子效率和低的自吸收等优点使其制成的激光器在未来光纤通讯领域中呈现了诱人的应用前景。新的有机激光材料不断涌现、器件结构不断推陈出新、新的激发原理不断提出并得到修正已经成为有机／聚合物固体激光研究领域的三大特点。本论文以研究有机材料的激光特性为目的，通过对有机染料DCJTB和三芳胺取代1，8-蔡酰亚胺齐聚物掺杂聚合物薄膜的放大的自发发射和受激发射特性的研究，探讨实现低闭值、高增益光泵浦有机聚合物激光的方法及影响器件性能的因素，阐明放大自发发射的工作机制，为进一步探讨电泵浦有机聚合物激光器提供材料体系和理论依据。1、研究了DCJTB掺杂聚合物薄膜的放大自发发射特性，分析了光泵浦条件下光谱窄化的放大自发发射机制，对ASE增益和损耗进行了讨论和数值拟合，并对增益方程进行了饱和修正。DCJTB：PS薄膜具有较低的闺值（0．16mJ·Pulse~(_1)·cm-2）、高的增益系数（40．72cm-1）、低的损耗值2．49cm一l和高的荧光量子效率（70．4％），其波导增益的波长分布呈明显的洛仑兹分布，增益饱和是均匀展宽的。与DCM比较发现，自由体积是决定材料性能的重要因素，大的自由体积有利于实现低闭值、高增益。我们的研究结果表明，DCJTB是非常好的激光介质材料。2、从ASE的发射波长、ASE闭值、增益和损耗四个技术指标出发，详细研究了激发光波长、聚合物基体、旋涂速度及基片等对DCJTB：PS薄膜放大自发发射（ASE）的影响，短的激发波长和合适的基体材料可以显著地降低闭值和提高增益，薄膜厚度和基片也对ASE性能有很大影响。利用琢lord镜面体系，研究了DCJTB染料掺杂相列向液晶体系的分布反馈激光特性，在电场作用下，可以有效地对TE、TM两种模式的输出强度进行调解。3、把电子传输／发光有机小分子材料Alq3掺杂到DCJTB和C545T掺杂聚合物薄膜，研究了它们的放大自发发射特性。通过在不同激发光波长激发下不同Alq3掺杂浓度对ASE性能影响的研究，发现掺杂Alq3显著地降低了闭值，增加了增益和减小了损耗。由于Alq3是一种良好的半导体有机发光材料，Alq3的引入对电泵浦有机聚合物激光器的研究具有重要的意义。4、研究了三种在4位氨基位置引入不同三芳胺功能基团的红光1，8-蔡酞亚胺齐聚物的放大自发发射特性，研究结果表明，三芳胺取代1，8蔡酞亚胺齐聚物具有低阂值、高增益和低损耗的特点，显示了较小的浓度淬灭效应，即使掺杂浓度高到60％仍可以观察到放大的自发发射现象，表明三芳胺取代1，8茶酞亚胺是一类非常有应用前景的有机半导体激光材料体系。

An Ameliorated Phase Generated Carrier Demodulation Algorithm With Low Harmonic Distortion and High Stability

A novel ameliorated phase generated carrier (PGC) demodulation algorithm based on arctangent function and differential-self-multiplying (DSM) is proposed in this paper. The harmonic distortion due to nonlinearity and the stability with light intensity disturbance (LID) are investigated both theoretically and experimentally. The nonlinearity of the PGC demodulation algorithm has been analyzed and an analytical expression of the total-harmonic-distortion (THD) has been derived. Experimental results have confirmed the low harmonic distortion of the ameliorated PGC algorithm as expected by the theoretical analysis. Compared with the traditional PGC-arctan and PGC-DCM algorithm, the ameliorated PGC algorithm has a much lower THD as well as a better signal-to-noise-and-distortion (SINAD). A THD of below 0.1% and a SINAD of 60 dB have been achieved with PGC modulation depth (value) ranges from 1.5 to 3.5 rad. The stability performance with LID has also been studied. The ameliorated PGC algorithm has a much higher stability than the PGC-DCM algorithm. It can keep stable operations with LID depth as large as 26.5 dB and LID frequency as high as 1 kHz. The system employing the ameliorated PGC demodulation algorithm has a minimum detectable phase shift of 5 mu rad/root Hz @ 1 kHz, a large dynamic range of 120 dB @ 100 Hz, and a high linearity of better than 99.99%.

细菌二氯甲烷脱氯酶基因对拟南芥的转化

The dichloromethane dehalogenase gene (dcm) of Methylophilus was cloned into the plasmid pKYLX71-35S2 and fused with the 35S2 promotor,then transformed Arabidopsis by the infiltration mediated with Agrobacterium tumefaciens. Homozygous dcm seeds were obtained after several generations selection on the medium with 50 mg L -1 kanamycin.Northern blotting showed dcm mRNA was high in cytoplasm and the detection of DCM enzyme indicated that the lines containing high dcm mRNA expressed high DCM enzyme activities. Fig 4, Ref 9

Amplified spontaneous emission and gain from optically pumped films of dye-doped polymers

The amplified spontaneous emission and gain characteristics of various fluorescent dyes, 2-(1,1-dimethylethyl)-6(2-(2,3,6,7-tetrahydro-1,1,7,7-tetramethyl-1H,5H-benzo[ij] quinolizin-9-1)ethenyl)-4H-pyran-4-ylidene) propanedinitrile (DCJTB) and 4-dicyanomethylene-2-methyl-6-(p-dimethyl-aminostyryl)-4H-pyran (DCM), doped in polystyrene (PS) matrices were studied and compared. It was found that DCJTB has a larger net gain, 40.72 cm(-1), a lower loss, 2.49 cm(-1), and a lower threshold, 0.16 (mJ/pulse)/cm(2), than DCM, which has a net gain of 11.95 cm(-1), a loss of 9.25 cm(-1), and a threshold of 4(mJ/pulse)/cm(2). The improvement of performance in DCJTB PS films is attributed to the larger free volume of DCJTB caused by the introduction of steric spacer groups into the DCJTB molecule.

Photoluminescent properties of dye-doped poly(N-vinyleabzole) (PVK) in microcavity

A surface emitting microcavity was formed by sandwiching a polymer film containing poly(N-vinyleabzole) (PVK). 8-hydroxyquinoline aluminium (Alq(3)) and 4-(Dicyanome thylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-Pyran(DCM) between a distributed Bragg reflector (DBR) with a reflectivity of 99% and a silver film. The sample was optically pumped with 250 ps pulses at 2 Hz repetition rate by a 355 nm line of the third harmonic of a mode-lock Nd:YAG laser. The lasing phenomenon was observed in DCM-doped PVK microcavity. The full width at half maximum (FWHM) was 3 nm with the peak wavelength at 602 nm. The threshold energy for lasing was estimated to be about 3 mu J. (C) 2000 Elsevier Science S.A. All rights reserved.

中国近海浮游植物光合作用研究——初级生产力模型计算与活体叶绿素荧光测量

本文的研究内容是初级生产力模型计算方法以及活体叶绿素荧光测量方法在我国近海浮游植物光合作用研究中的应用。 论文对在我国近海实测的1321 组叶绿素垂直分布数据以及84 组初级生产力数据进行了非线性拟合分析，得出了描述叶绿素和初级生产力垂直变化规律的相应参数。结合光合参数——初始斜率α 的平面分布将我国近海分为9 个光合作用特征相对独立的分区。以光强和遥感叶绿素为输入变量，以各分区实测参数的平均值为模型参数，首次建立了分海区的时间－深度积分初级生产力计算模型。 对拟合参数的分析表明：我国近海深水叶绿素峰（DCM）在夏季最明显而在冬季则不明显，这与夏季温跃层的形成和冬季温跃层消失的规律相符合。最大光合速率参数主要受温度和营养盐状况的影响，但整体而言各个季节的变化不大。光合作用初始斜率参数主要受浮游植物光照条件和光照历史的影响，从春季到冬季持续增加，基本与光照强度的变化刚好相反。光抑制参数反映着浮游植物对高光强伤害的敏感性，它在夏、秋季较低而在冬季较高。 模型计算结果表明我国近海初级生产力规模约为6.4±1.0×108tC/a。总体来说我国近海海域初级生产力北方高于南方，西部高于东部。北方初级生产力高峰期大都出现在夏季而南方出现在冬季，中部则高峰期出现在春秋两季，与温跃层出现和消失的规律有一定的相关性。与由实测生产力推算的初级生产力相比，本模型的计算结果较高，误差产生的原因包括二类水体遥感叶绿素浓度偏高、地形因素等。与VGPM相比较，本模型的计算结果更接近于实测结果。模型中云覆盖度参数的变化可能引起计算结果约25％的变化，当取云覆盖度参数为0.5 时的计算结果与用实际天气状况数据的计算结果较为接近。制作了基于分区模型的水柱初级生产力计算软件，可在仅测量叶绿素浓度的情况下进行水柱初级生产力的计算。 模型准确度的进一步提高的途径主要包括实测参数数量的增加以及遥感叶绿素浓度准确性的提高。 与初级生产力相比，活体叶绿素荧光测量可以更快速、简便地跟踪浮游植光合作用动态。本研究首次将活体叶绿素荧光测量方法应用于野外浮游植物光合作用状态研究。通过暗驰豫实验，建立了使用OS5－AFM藻类荧光仪现场测定活体叶绿素荧光参数——Fv/Fm（光化学效率）的操作方法，并对胶州湾海域浮游植物光化学效率进行了高时空分辨率的调查，对相关因素进行了分析，并尝试通过Fv/Fm进行初级生产力计算。 结果表明，胶州湾海域表层Fv/Fm值的全年平均值约0.37，处于中等偏低水平。Fv/Fm值在秋季最高而春季最低，其平面分布在夏季较均匀而在春季则有较大的区域差异。湾东部Fv/Fm值变化幅度较大，一年中有4 个高峰期；而湾西部Fv/Fm值变化幅度较小，一年中有3 个高峰期。光合作用最活跃的海区随季节更替而变化，其年变化模式可能具有一定的重复性。不同深度上Fv/Fm值的海区平均值没有显著差异，但底层Fv/Fm值的空间差异较小。 通过对营养盐和Fv/Fm值时间变化的分析，首次发现了自然水体中Fv/Fm值变化对氮盐浓度变化响应的滞后效应，在不同的站点，影响Fv/Fm值的氮盐种类有所不同，湾西部海域与NH4+相关性较高而湾东部海域与NO3-的相关性较高，P、Si等则与Fv/Fm值基本无相关性。滞后期的长度并不稳定，1 旬和2 旬的滞后现象都可观察到。Fv/Fm值变化率与氮盐浓度变化率之间的相关性高于Fv/Fm值与氮盐浓度之间的相关性。这表明即使在胶州湾这样无机氮浓度很高、浮游植物生长基本不受氮源限制的水体，氮源浓度的变化仍然影响着浮游植物的光合作用状态。 初步建立了由Fv/Fm测量结果计算初级生产力的方法。模型的计算结果与文献资料中胶州湾水域初级生产力的时空分布趋势基本一致，但在数量上明显低于传统估算的结果。获得更多同步测量的初级生产力和Fv/Fm值数据可逐渐改善这一方法计算结果的准确性，并可籍次方法更快更方便地进行初级生产力的测算。

便携式移动机器人INS/GPS组合导航系统研究

基于捷联惯导系统（INS）与全球定位系统（GPS）定位技术的发展以及机器人导航的需要，本文对INS与GPS的组合导航系统进行了研究。捷联惯导系统与GPS导航各有优缺点，具有互补性，文中将两者结合形成了更加准确可靠的定位系统。本文首先介绍了捷联惯导系统和全球定位系统，并对捷联惯导和GPS的误差作了详细的分析，建立了误差模型。文中应用动力学误差方程建立了九状态INS/GPS综合卡尔曼滤波方程。提出了一种以位置、速度、姿态DCM的误差为状态量，以GPS和INS的位置差作为观测量的INS/GPS组合导航系统的滤波算法，并将该技术应用于机器人的定位导航。仿真实验表明，该算法可有效提高系统导航参数的估计精度。本文分五章对该课题进行了研究。第一章是引言，介绍了课题的研究背景、意义，国内外的研究现状和本文的主要工作；第二章介绍了惯性传感器和GPS接收器的原理和特性；第三章介绍了捷联惯导系统相关的理论知识，包括姿态角的解算，算法具体内容和误差分析，并对捷联惯导系统进行了仿真试验；第四章介绍了Kalman滤波的相关知识并详细介绍了INS/GPS组合导航系统；第五章对INS/GPS组合导航系统的九状态卡尔曼滤波算法进行了仿真，并对试验结果进行了详细的分析。从仿真结果可知，组合导航系统大大的提高了系统的精度，克服了纯惯导系统的缺点。

视觉通路在汉字组块破解过程中的有效连接

The present study used Dynamical Causal Modeling (DCM) to reveal the influence of difficult to decompose Chinese characters on the effective connectivity of “where” and “what” visual stream。 Chunk decomposition is to decompose the familiar items to their components and then to make up new items with the decomposed components。 Some previous studies with eye movements and brain image had revealed that the chunk decomposition was involved visual-spatial information process, and suggested that “what” and “where” visual streams contributed to the course of chunk decomposition。 However, how they worked to complete the chunk decomposition task is still unknown。 The present study has two factors, familiarity and tightness of the spatial structures, each with 2 levels: real words vs. pseudowords and tight chunks vs. loose chunks。 The results indicates that in the loose conditions, familiarity increases the effective connectivity of “where ” stream, while in the pseudowords conditions, tightness of the spatial structures increases the effective connectivity of both “where” and “what” streams, and familiarity and tightness combined to increase not only both the “what” and “where” streams, but also the effective connectivity from the inferior temporal gyrus to the superior parietal lobule.