共查询到20条相似文献,搜索用时 125 毫秒
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应用DPR方法(the discrete position representation method)编程计算了双原子分子Li2三种低电子态和LaF分子基态的振转能级以及非绝热近似下K2分子在不同电子束缚态之间发生振转跃迁的Franck-Condon因子.计算结果与现有的文献值符合得很好,相对误差均小于1%,可以为双原子分子振转光谱的实验研究提供参考数据,计算程序可以推广应用到其它双原子分子以及多维量子系统的数值计算中. 相似文献
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基于在539.75nm,632.8nm,1079.5nm,1341.4nm波长上和288K,338K,383K,423K温度条件下,对掺5mol%MgO和0.2mol%Ti的LiNbO_3晶体的主折射率的精密测量 ̄[1],根据对LiNbO_3晶体适用的修正的Sellmeier’s方程,以解出参数C_i表达式的方法,求出上述温度时Sell-meier’s方程的参数A_i,B_i,C_i,D_i,以最小二乘法精确地拟合上述参数对温度T的线性关系,进而推导出这种晶体的折射率温度系数的表示式。利用此表示式可以计算波长在539.75nm~1341.4nm区间附近,温度在288K~423K范围左右Ti:Mg :LiNbO_3晶体的折射率温度系数。为检验该折射率温度系数表示式的实用性,利用此表示式计算1079.5nm为基波的该晶体的二倍频非临界相位匹配温度,与实验值之差在1K以内,从而证明这个折射率温度系数表示式对于采用Ti:Mg:LiNb_O,晶体设计非线性光学器件是适用的。 相似文献
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雪崩倍增效应是4H-SiC雪崩光电二极管、功率半导体器件等器件的关键机理。作为其中最重要的物理参数,雪崩倍增因子(M)的精确解析表达式目前未见报道。文章提出4H-SiC p-n结M的精确计算方法及其解析表达式。基于更准确的碰撞电离模型,通过MATLAB对4H-SiC单边突变结(p+-n)电子和空穴的碰撞电离积分(I)进行精确的数值计算,给出击穿电压(BV)随掺杂浓度的经验表达式,进一步提出电离积分随外加电压及掺杂浓度的拟合表达式。此外,对外加电压接近BV的情形进行细致的相对误差分析,表明电子电离积分受电场影响显著。对于雪崩光电二极管及功率器件较宽的BV范围,所提出的拟合表达式在外加反向偏压大于0.65BV时具有较高的精确度(相对误差小于5%)。 相似文献
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Mie散射因子的计算方法及其应用 总被引:1,自引:0,他引:1
在推导Mie散射因子计算迭代公式之后,介绍了几种Mie散射因子的近似计算方法,并给出了相应的计算结果和工程应用分析,为散射探测和散射物理量的计算提供参考. 相似文献
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掺氮6H—SiC材料电学性质温度依赖关系测量与分析 总被引:1,自引:0,他引:1
测量了7-1000K的掺氮6H-SiC材料基本电学性质,用电子性方程对载流子浓度温度倒数关系曲线进行拟合,利用化全物半导体散射机构计算了行 率。数据拟合分析得到样品的掺杂浓度、补偿浓度、杂质激光活能和载波子有效质量。分析结果表明,控制杂质能级和表观杂质激活能由补偿度和杂质浓度决定。掺氮6H-SiC材料预期有0.08eV、0.12eV两个能级,当补偿杂质浓度大于较小能级浓度时,材料将由较高的能级控制 相似文献
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本文对频率复胳系统同信道干扰抑制因子提出了解析和统计两种求解方法,并利用统计求解结果,证明了解析求解法在实际情形中应用的可行性。 相似文献
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Peng LM 《Journal of electron microscopy》2005,54(3):199-207
High-energy electrons may be elastically and inelastically scattered by a solid. To a good approximation the effect of inelastic scattering on the elastically scattered electrons may be taken into account using the concept of the complex optical potential. The optical potential may be calculated using electron atomic scattering factors and Debye-Waller factors, which in turn can be evaluated numerically using Hartree Fock atomic wave functions and shell models of lattice dynamics. The numerical electron atomic scattering factors have been parameterized using five Gaussian functions for all the neutral atoms of the periodic table and for 106 important ions, and the temperature-dependent Debye-Waller B-factors have been fitted by using fourth degree polynomial regression fitting for 19 compounds with the sodium chloride structure, 5 compounds with the cesium chloride structure, 17 compounds with the zinc-blend structure and 68 elemental crystals. 相似文献
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Monte Carlo方法模拟低能电子束曝光电子散射轨迹 总被引:11,自引:5,他引:6
建立了一个适用于描述低能电子散射的物理模型 ,利用 Monte Carlo方法对低能电子在多元多层介质中的散射过程进行模拟 .低能电子弹性散射采用较严格的 Mott截面描述 ,为了节约机时 ,利用查表与线性插值方法获得 Mott截面值 ;低能电子非弹性散射能量损失采用 Joy修正的 Bethe公式计算 ,并对其加以改进 ,引入多元介质平均电离电位、平均原子序数、平均原子量概念 ,利用线性插值方法给出光刻胶 PMMA对应的 k值 .对电子穿越多层介质提出一种新的边界处理方法 .在此基础上运用 Monte Carlo方法模拟高斯分布低能电子束在 PMMA-衬底中的复杂散射过程 . 相似文献
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借助高分辨电子显微像校正电子衍射强度的动力学效应 总被引:1,自引:1,他引:0
针对高分辨电子显微学和电子衍射相结合测定晶体结构的图像处理技术,提出了一种借助高分辨电子显微像来校正低散射角电子衍射强度动力学效应的新方法,将此法试用于Bi2(Sr0.9La0.1)2CoOy晶体结构分析,结果说明此法有效。 相似文献
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电子显微镜的现状与展望 总被引:16,自引:5,他引:11
本文扼要介绍了电子显微镜的现状与展望,透射电子显微镜方面主要有:高分辨电子显微学及原子像的观察,像差校正电子显微镜,原子尺度电子全息学,表面的高分辨电子显微正面成像,超高压电子显微镜,中等电压电镜,120kV,100kV分析电镜,场发射枪扫描透射电镜及能量选择电镜等,透射电镜将又一次面临新的重大突破,扫描电子显微镜方面主要有:分析扫描电镜和X射线能谱仪,X射线波谱仪和电子探针仪,场发射枪扫描电镜和 相似文献
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The image deconvolution technique in combination with dynamical scattering effect correction developed previously for crystal defect investigation has been modified to meet the needs of interface studies and applied to a [111] twin model of Si. Elliptical windows are utilized as a new means for Fourier filtering and correcting the amplitudes of reflections. Images were simulated with a 200 kV field-emission high-resolution electron microscope. After image restoration, four images simulated with different defocus values were transformed into structure images with atomic columns revealed individually at correct positions. The effectiveness of the technique is discussed. 相似文献
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A numerical method to compute scattering amplitudes for time harmonic waves scattered from infinite cylinders with arbitrary uniform cross section is described. A nonlocal boundary condition is used to develop a variational formulation of the scattering problem, and the finite element method is applied to determine approximations to the near field. Scattering amplitudes are then determined by means of an integral representation obtained from Green's formula and properties of the nonlocal boundary operator. Computational results are presented to illustrate the method's application. 相似文献
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Demir V. Elsherbeni A. Worasawate D. Arvas E. 《Antennas and Propagation Magazine, IEEE》2004,46(5):94-99
Various numerical techniques have been developed for modeling electromagnetic field propagation in various novel complex media. The validity of these techniques is usually verified by comparison to the exact solutions of canonical problems. Recently, research has focused on chiral media, a subclass of materials known as bianisotropic materials, and numerical techniques have been developed in order to calculate the interaction of electromagnetic fields with chiral objects. One canonical problem for these techniques is plane-wave scattering from a chiral sphere. This work presents a software package that displays and saves the calculated data for the scattering from a chiral, dielectric, or perfectly conducting sphere using a friendly graphical user interface (GUI). 相似文献