基于图形化生长纳米氧化锌场致发射阴极阵列的研究

采用光刻技术在覆盖有氧化锌(ZnO)薄膜的ITO玻璃片衬底上实现图形化生长,结合水热法在衬底上制备出结构完整、排列一致的ZnO矩形和圆环型单元阵列。在图形化的基础上二次生长ZnO纳米锥阵列,锥长度最大可达到10μm,远大于一次生长的长度,并且发现锥顶有很多精细的类似针状的纳米量级微细结构。分析了非图形化、图形化一次以及图形化二次生长的ZnO纳米锥阵列的场致发射性能。使用图形化二次生长的ZnO纳米锥阴极阵列制作了12.7cm(5inch)的场发射显示器(FED),能实现全屏发光。实验结果表明,图形化二次生长的ZnO纳米锥阵列发射电流密度为最大,可达0.6mA/cm2,其开启场强为2.5V/μm。图形化生长ZnO纳米锥的方法是一种能较好改善材料场发射性能的好方法,为寻求良好场发射性能材料的制备提供了一条有效的实验途径。     

掺AlZnO纳米线阵列的光致发光特性研究

采用化学气相沉积方法，以金做催化剂，在Si (100)衬底上制备了掺AlZnO纳米线阵列.扫描电子显微镜(SEM)表征发现ZnO纳米线的直径在30nm左右.X射线衍射(XRD)图谱上只存在ZnO的(002)衍射峰，说明ZnO纳米线沿c轴择优取向.掺AlZnO纳米线阵列的室温光致发光(PL)谱中出现了3个带边激子发射峰：373nm，375nm，389nm.运用激子理论推算出掺AlZnO纳米线的禁带宽度为3.343eV ，束缚激子结合能为0.156eV；纯ZnO纳米线阵列PL谱中3个带边激子发射 关键词： 光致发光 化学气相沉积(CVD) 激子 ZnO纳米线阵列     

四针氧化锌制备及其场致发射特性

采用了VS(Vapor-Solid)的方法制备了四针状ZnO,以此作为场致电子发射的冷阴极材料。并对材料进行了扫描电镜(SEM)和X射线粉末衍射(XRD)测试分析,揭示其表面形态和晶体结构。同时将阴极与印刷有荧光粉的阳极板组装成二极管结构场致发射显示屏,并进行了场致发射特性实验。该二极管结构的开启电压为3.6V/μm,其阈值电压为6.6V/μm,相应的电流密度为0.2mA/cm2,并且具有稳定的电流密度和均匀的显示效果。实验证明ZnO是一种优良的场致发射冷阴极材料,具有广阔的应用前景。     

氧化锌纳米线的紫外光耦合增强场电子发射特性

本文采用热化学气相沉积方法制备氧化锌纳米线阵列, 研究氧化锌纳米线阵列在紫外光辐照下的场电子发射特性. 实验结果表明, 在紫外光辐照下, 氧化锌纳米线场发射开启电压降低, 发射电流明显增大. 机理分析认为, 氧化锌纳米线紫外光增强的场发射源自场电子发射与半导体耦合作用, 紫外光激发价带电子跃迁到导带和缺陷能级使发射电子数量增加, 同时, 光生电子发射降低了发射材料表面的有效功函数, 从而显著增强场电子发射性能. 氧化锌纳米线具有紫外光耦合增强场电子发射特性, 在光传感、冷阴极平板显示和场发射电子源等方面具有潜在的应用价值.     

氧化锌纳米棒场发射性能研究

采用简单物理气相沉积法制备出取向和非取向的氧化锌纳米棒，他们的场致电子发射性能测量结果表明，ZnO纳米棒具有较好的场发射性能，但是高度取向的ZnO纳米棒阵列并不利于获得高的场致电子发射电流密度.这可能是由于高密度ZnO纳米棒之间具有较高的屏蔽效应，降低了ZnO纳米棒阵列的场放大因子，从而影响了其场发射性能.相反，非取向ZnO纳米棒由于相互之间的屏蔽效应比较弱，而且表面存在容易成为发射中心的微小突起，表现出较好的场发射效果.这些结果不仅有助于加深我们对准一维纳米材料场致电子发射性能的理解，也为未来场发射电子器件的实际应用提供了可靠的依据. 关键词： 氧化锌 场发射 非取向     

低温CVD法在玻璃衬底上制备ZnO纳米线阵列

采用化学气相沉积(CVD)法在镀Cr(20nm)的玻璃衬底上,低温制备了ZnO纳米线阵列。利用扫描电子显微镜(SEM)和X射线衍射(XRD)对样品的表面形貌和微结构进行了分析表征。结果表明:源分解温度1350℃,衬底温度450～500℃,氩气流量为35sccm时,ZnO纳米线在玻璃衬底上呈现有序生长;XRD谱图中只观测到ZnO(002)衍射峰。表明制备的纳米线阵列具有高度c轴择优取向生长特性和较高的结晶质量。     

硅纳米线尖端阵列的制备及其场发射性能研究

将银镜反应与金属催化化学刻蚀相结合,在室温附近成功地制备出了硅纳米线尖端阵列,其长度为4~7μm,中间部分的直径在100~300nm之间。该方法操作简单、高效、无毒、可控以及低成本,且不需要高温、复杂的设备,对环境也没有特殊要求。性能测试结果显示:该硅纳米材料能够有效实现电子发射,开启电场约为2.7V/μm(电流密度10μA/cm2处);硅纳米尖端阵列的场增强因子约为692,可应用在场发射器件之上。     

生长温度对纳米氧化锌场发射性能的影响

采用锌粉和银粉为蒸发源,用热蒸发法不同温度下制备了四针状纳米氧化锌,并以单独的锌粉做对照。采用扫描电子显微镜(SEM)观察其形貌,X射线衍射(XRD)谱表征其晶体结构。采用丝网印刷方法将其制备为场致电子发射阴极,将阴极与印刷有荧光粉的阳极板组装成二极结构场致发射显示屏,并进行了场致电子发射特性对比实验。结果表明较高温度制备的氧化锌具有较好的场致发射性能;掺杂银粉的蒸发源制备的样品的发射性能明显优于没有掺杂银粉的样品。实验证明ZnO是一种优良的场致发射冷阴极材料,在真空电子方面具有广阔的应用前景。     

高取向As掺杂ZnO纳米线阵列的制备与表征

在不采用任何金属催化剂的条件下,运用化学气相沉积法,在Si(100)衬底上制备出高取向的As掺杂ZnO纳米线阵列.样品的X射线衍射(XRD)谱显示获得了单一取向的衍射峰,表明样品具有较好的结晶质量.场发射扫描电镜(FE-SEM)观察表明,As掺杂ZnO纳米线阵列具有均一的直径和长度,其顶部和根部直径分别为70 nm和1...     

高分子软模板法自组装生长ZnO纳米线及其光学性能

采用自组装技术,利用均聚极性高分子(聚丙烯酰胺、聚乙烯醇等)长分子链作为自组装模板在半导体硅衬底上自组装生长出ZnO纳米线。采用扫描电镜(FE-SEM)和透射电镜(HRTEM)对样品的表面形貌和结构分析表征的结果表明,ZnO纳米线直径约50~80nm、长度大于4μm,具有六方纤锌矿单晶结构,且沿c轴方向择优取向生长。采用室温下光致发光(PL)谱和紫外吸收(UV)光谱对制得的ZnO纳米线的光学性能研究表明,其PL光谱上有较强的紫外发射和较弱的蓝光发射,UV吸收光谱表明样品在紫外区有强的宽带吸收,且随着纳米线粒径的减小,吸收峰出现了蓝移现象。研究探讨了高分子诱导ZnO纳米线自组装定向生长机制、发光机理及其与工艺条件的内在联系。     

白光和红绿蓝光LED可调光源研制

为了提高LED光源色温和亮度的调节精度和准确度,结合色温由低向高变化时光色所呈现的渐变特点,提出了一种低色温白光LED灯珠、高色温白光LED灯珠加红绿蓝光LED灯珠补偿式调光的方法.将色温分成三个部分进行调节,每个部分选用不同的LED灯珠组合来进行调光.实验结果表明:不同组合情况下的LED光源的初始输出色温相对于目标值的偏差范围在1％以内;亮度可以在保证色温不变的情况下独立进行调节,初始输出值与目标值的偏差范围在1％以内;经过微调之后可以达到目标值;达到了色温和亮度独立调节的要求;光源发光稳定,不会因为长时间工作而影响调节精度.     

Visualization and interferometry for cylindrical and spherical sample tomography and profilometry

A technique combining image processing and laser interferometry for visualizing and detecting the deformation of transparent cylindrical and spherical sample is proposed. This deformation includes geometric deformation such as volume transition in profilometry and physical deformation such as refractive index change in tomography. Phase contour lines are used for quantitative analysis and graphical representation of the deformation. This method allows us to visually detect the spatial variation of the deformation field and to evaluate the test quality such as misalignment of optical system. A theoretical analysis using phase contour map to characterize the deformation field is described in detail. A method using phase contour map to qualify the interferometric test is proposed. Analysis of test examples is carried out. Suggestions on using phase contour line method to ameliorate test system design are finally discussed.     

Quantum and Classical Disparity and Accord

Discrepancies and accords between quantum (QM) and classical mechanics (CM) related to expectation values and periods are generally found for both the harmonic oscillator (SHO) and a free particle in a box (FPB), which may apply generally. These indicate non-locality is expected throughout QM. The FPB energy states violate the Correspondence Principle. Previously unexpected accords are found and proven that 〈x ²〉 _CM =〈x ²〉 _QM and τ _CM =τ _QMb (beat period i.e. beats between the phases for adjoining energy states) for the SHO for all quantum numbers, n. However, for the FPB the beat periods differ at small n. It is shown that a particle’s velocity in an infinite square well varies, no matter how wide the box, nor how far the particle is from the walls. The quantum free particle variances share an indirect commonality with the Aharonov-Bohm and Aharonov-Casher effects in that there is a quantum action in the absence of a force. The concept of an “Expectation Value over a Partial Well Width” is introduced. This paper raises the question as to whether these inconsistencies are undetectable, or can be empirically ascertained. These inherent variances may need to be fixed, or nature is manifestly more non-classical than expected.     

黑克、布劳、及伯曼-温采尔代数的诱导及分导系数和量子经典李代数的耦合与重新耦合系数

本文总结了计算黑克、布劳、及伯曼 温采尔代数在各种工数链下诱导及分导系数的线性方程方法(LEM)。特别强调了关于A,B,C,D型李代数及其量子情形与其中心代数之间的舒尔 魏尔 布劳双关性关系。这一关系使我们能够利用相应中心代数的诱导及分导系数计算出经典李代数及其量子情形的耦合与重新耦合系数。讨论了从该方法得到B,C,D型李代数不可约表示克罗内克积分解的应用。基于LEM还得到了处理对应于置换群CG系列问题的黑克代数张量积的方法。     

Rapid and flexible laser marking and engraving of tilted and curved surfaces

We present a novel method for rapid and flexible laser marking and engraving of tilted, curved and freeform work-piece surfaces. The method is based on integrating a three-dimensional (3D) laser measurement system into a 3D laser marking system. We use the same laser source and optics for measurement and processing with a minimum of additional hardware components. A low power CW laser regime is used to measure the 3D shape of a work-piece surface while a high-peak power-pulsed laser regime is used for processing. The acquired 3D surface data are used to determine the 3D trajectory of the processing beam focus. Neither the 3D shape of the work-piece nor its orientation needs to be known in advance as long as the processed surface lies within the working range of the 3D laser processing system. This eliminates the need for exact work-piece positioning before processing and substantially improves processing flexibility (allowing, e.g. variations in work-piece shape or/and orientation from mark to mark). This paper discusses key issues concerning an implementation of the method and presents typical examples of markings and engravings, which demonstrate the advantages of the method with respect to the existing industrial 2D and 3D laser marking and engraving methods. The method can also be applied to flexible laser structuring and microprocessing of curved surfaces.     

Spectroscopy and Photophysics of Iso- and Alloxazines: Experimental and Theoretical Study

We present a systematic study of the effect of methyl substitution on iso- and alloxazines in acetonitrile solutions. Substitution patterns have profound effects on both spectral and photophysical properties, with fluorescence quantum yields varying by more than an order of magnitude. TD-DFT calculation were used for the first time to correlate electronic structure changes with the substitution patterns, with good agreement between calculated and theoretical band positions and oscillator strengths. Both n-pi* and pi-pi* states in these compounds are predicted, with the oscillator strengths indicating that only the pi-pi* states should be observable in the absorption spectra. Substitution patterns are shown to be responsible for energy order inversion between these states.     

Nano and micro-scale fluid and plasma dynamics: present and future applications

In this letter, we illustrate the importance of fluid dynamics research by considering two particular areas of study: nano- and micro-scale fluid and plasma dynamics. We show how improved scientific knowledge of nano- and micro-fluid dynamics can significantly enhance our future. Application is also discussed regarding environmental aspects.     

Geometry and Elasticity of Strips and Flowers

We solve several problems that involve imposing metrics on surfaces. The problem of a strip with a linear metric gradient is formulated in terms of a Lagrangian similar to those used for spin systems. We are able to show that the low energy state of long strips is a twisted helical state like a telephone cord. We then extend the techniques used in this solution to two–dimensional sheets with more general metrics. We find evolution equations and show that when they are not singular, a surface is determined by knowledge of its metric, and the shape of the surface along one line. Finally, we provide numerical evidence by minimizing a suitable energy functional that once these evolution equations become singular, either the surface is not differentiable, or else the metric deviates from the target metric.     

激光跟瞄仿真系统及两种跟瞄方法

基于OpenGL和大气传输光学分析的3维全数字仿真是激光跟瞄系统的重要研究手段。为提高跟踪和瞄准精度,从激光跟瞄仿真系统整体出发,研究了目标成像中的投影变换、成像与跟踪的关系、高精度跟踪现有算法的控制过程仿真等内容,并提出了基于大视口、目标大气传输图像序列的跟瞄仿真技术。说明了仿真系统中跟瞄精度分析的特点。就某仿真场景,设计了"头部顶点"和"两点提取"两种跟瞄方法,在不同大气湍流条件下得到了它们的跟瞄精度,说明应用该激光跟瞄仿真系统,能够预先设计、测试和验证一些跟瞄方法,帮助进行算法分析和改进,从而提高工作效率和节约成本。