Energy and life of electrons and holes in the columnar nanometer system北大核心CSCD

利用S-矩阵理论,在有效质量近似下,求出柱状纳米系统电子和空穴的能量和寿命,并与球状纳米系统相比较.以HgS/CdS/HgS柱状纳米系统为例,探讨了线度和势垒宽度对电子和空穴的能量和寿命的影响.结果表明:柱状纳米系统中,电子和空穴的能量和寿命随线度的变化规律相似,即势垒宽度一定时,能量随内半径增大而减小,寿命随内半径增大而增大;内半径一定时,能量随势垒宽度增大而减小,但变化甚微,而寿命随势垒宽度增大而迅速增大;势垒宽度Δ<4aCdS时,电子和空穴的寿命均为零,但电子和空穴寿命不为零的势垒宽度范围不同,空穴的寿命要比电子的寿命小.柱状和球状纳米系统电子和空穴寿命的变化规律相似,形状的影响很小.     

HgS/CdS/HgS球状纳米系统电子的能量与寿命以及概率分布

建立了HgS/CdS/ HgS球状纳米系统物理模型和电子状态满足的方程.应用S矩阵理论，探讨了 s态电子的能量和寿命以及概率分布随势垒和势阱宽度的变化规律.结果表明：电子能量和寿 命随垒势宽度增大而增大；电子能量随阱宽增大而减小，而寿命随阱宽增大而增大；层间相 互作用对结果有重要影响. 关键词： 球状纳米系统 电子能量和寿命 电子概率分布 势垒势阱宽度     

层间作用对HgS/CdS/HgS柱状纳米系统电子能量的影响

确立了柱状纳米系统电子势能随距离的变化关系，以HgS/CdS/HgS柱状纳米系统为例，讨论了层间作用对电子能谱的影响.结果表明：电子能量随势垒宽度和波矢的增大而增大，随势阱宽度的增大而减小；层间互作用会增大电子能量，但不会改变电子能量随势阱和势垒以及波矢的变化趋势. 关键词： 层间作用势 HgS/CdS/HgS柱状纳米系统 电子能量     

层间作用和线度对球状纳米系统电子能量的影响

建立了考虑层间作用情况下两层球状纳米系统的物理模型,应用格林函数法和傅里叶展开,求出系统电子的势能.以HgS/CdS球状纳米系统为例,讨论了系统线度和层间作用对电子能量的影响.结果表明：层间作用会使电子势垒平均高度比不考虑时有所降低;层间作用愈大,电子势垒高度降低得愈多,电子势能曲线起伏就愈大.层间作用相同时,电子基态能以及层间作用引起的能量修正均随粒子线度增大而减小;而粒子线度相同时,层间作用引起的能量修正却随层间作用的增大而增大. 关键词： 层间作用 线度 HgS/CdS球状纳米系统 电子能量     

线度和势垒宽度对球状纳米系统电子散射截面的影响

在有效质量近似和球形方形势模型下,计算了开放型球状纳米系统电子散射截面及电子按能量的概率分布,探讨了线度、势垒宽度对电子散射截面和共振能量以及共振宽度的影响.结果表明:电子的散射截面随能量的分布曲线有一极大值和极小值,而且电子能量的概率分布曲线的极大值位置总是介于散射截面分布曲线的极大值与极小值的能量位置之间;散射截面随内核半径r₀的增大而增大,而且散射截面分布曲线随r₀的增大由较平滑变得较尖锐;散射截面随势垒宽度Δ的增大而增大,但在Δ＝1.4a_CdS–1.7a_CdS的范围内,变化出现异常,在Δ=1.6a_CdS时散射截面出现极小;电子共振能量E_l 随Δ的变化与电子所处状态有关,而电子共振宽度Γ_l随Δ的增大而减小;不论Δ取何值, E_l和Γ_l都满足能量和时间的测不准关系. 关键词： 球状纳米系统 势垒宽度 电子散射截面 电子概率分布     

CdS/HgS/CdS球状纳米系统高能级斯塔克线度效应

研究了在层间作用和电场作用下球状纳米系统的电子能量和波函数.以CdS/HgS/CdS球状纳米系统为例,讨论了层间作用、电场和样品线度对高能级斯塔克效应以及谱线频率和强度的影响.结果表明：CdS/HgS/CdS球状纳米系统在外电场作用下发生斯塔克效应的能级分裂规律与氢原子类似,但能级位移量不同.谱线频移与电场强度的平方成正比,多数谱线的频移随线度增大而减小,少数谱线的频移则相反;而层间作用引起谱线的频移随线度增大而减小.除少数谱线外,多数谱线的相对强度随线度增大而减小,层间作用不会改变相对强度随线度的变化趋 关键词： CdS/HgS/CdS球状纳米系统 斯塔克效应 谱线频率 谱线强度     

圆柱状量子点量子导线复合系统的激子能量和电子概率分布

建立了圆柱状量子点量子导线复合系统中激子满足的方程，用微扰论求出激子能量.以CdS/HgS/CdS/HgS/CdS圆柱状量子点量子导线复合系统为例，研究了系统中电子的概率分布和系统线度对激子能量的影响.结果表明：系统中电子、空穴以及激子的能量均随量子点高度h₀的增大而减小，电子-空穴相互作用对基态激子能量的影响要大于激发态；电子沿径向方向的概率分布呈起伏状，在轴线和表面附近的概率趋于零，而在R/2附近概率最大；在量子点附近电子沿轴向方向的概率分布呈振荡特征 关键词： 量子点 量子导线 激子 能量     

有限深势阱里量子盘中极化子的基态性质

采用平面波展开、幺正变换和变分相结合的方法推导出有限深势阱里量子盘中极化子的基态能量公式.采用极化子单位进行数值计算,结果表明极化子的基态能量随势垒高度和势垒宽度的增大而增大,原因是势垒愈高、愈宽,电子穿透势垒的可能性愈小,导致电子能量增大,进而导致极化子基态能量增大.数值计算结果还表明极化子的基态能量随量子盘有效受限长度和量子盘半径的增大而减小;声子效应导致极化子能量较电子能量低.     

球状纳米系统高能级斯塔克效应和谱

以三层CdS/HgS/CdS球状纳米系统为例,研究了在电场和层间作用下球状纳米系统高能级斯塔克效应的能级分裂规律以及谱线的频率、强度和自发幅射系数的线度效应. 结果表明,系统的斯塔克效应在只有电场时,能级是按1,3,…,(2n—1)的规律进行分裂,与氢原子类似;有电场和层间同时作用时,能级是按1,4,…,n²的规律进行分裂. 量子跃迁时各谱线的频率均随系统线度增大而减小,除少数谱线外,多数谱线的强度随线度增大而减小,而自发幅射系数随线度增大而增大;电场会引起谱线的频率发生改变,其谱线频移量与电场强度的平方成正比;除少数谱线外,电场和层间作用引起的谱线频移量均随线度增大而减小;层间作用会使电子的能级稍有降低,稍微增大谱线的强度和自发幅射系数值,但它不会影响谱线的频率、强度和自发幅射系数随线度的变化趋势,在线度较小时层间作用的影响才显著.     

有限深势阱里量子盘中极化子的基态性质

采用平面波展开、幺正变换和变分相结合的方法推导出有限深势阱里量子盘中极化子的基态能量公式.采用极化子单位进行数值计算,结果表明极化子的基态能量随势垒高度和势垒宽度的增大而增大,原因是势垒愈高、愈宽,电子穿透势垒的可能性愈小,导致电子能量增大,进而导致极化子基态能量增大.数值计算结果还表明极化子的基态能量随量子盘有效受限长度和量子盘半径的增大而减小;声子效应导致极化子能量较电子能量低.     

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。     

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.     

国外超导材料技术研究政策和方向

超导材料技术是21世纪具有战略意义的高新技术,极具发展潜力和市场前景。世界各发达国家纷纷制定研发计划,给予高度重视和大力支持,加快超导材料技术的基础研究和产业化发展。主要从美国、日本、欧洲国家、韩国等国家的相关研发计划、政策以及主要科研机构的研发概况出发,阐明目前国外超导材料技术的研究政策和方向。     

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.     

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.     

Divergence- and Curl-Preserving Prolongation and Restriction Formulas

We present new second-order prolongation and restriction formulas which preserve the divergence and, in some cases, the curl of a discretized vector field. The formulas are suitable for adaptive and hierarchical mesh algorithms with a factor-of-2 linear resolution change. We examine both staggered and collocated discretizations for the vector field on two- and three-dimensional Cartesian grids. The new formulas can be used in combination with numerical schemes that require a divergence-free solution in some discrete sense, such as the constrained transport schemes of computational magnetohydrodynamics. We also obtain divergence-preserving interpolation functions which may be used for streamline or field line tracing.