碳纳米管场发射特性的研究

自1995年首次报道碳纳米管电子场发射实验研究以来,碳纳米管被认为是最具应用潜力的电子场发射极,特别是近几年碳纳米管合成技术的发展更促进了碳纳米管作为场发射电子源的研究。本论文对碳纳米管作为场发射电子源的研究进行了系统的总结,简洁地介绍了碳纳米管电子场发射研究的方法、理论、主要发现及意义。     

Transmission Loss due to Modes Conversion Caused by Random Surface Imperfections in Left-Handed-Material Slab Waveguides

Based on the orthogonality relations among the modes in left-handed-material （LHM） slab waveguides （SWGs）, we derive the coupled equations among the modes caused by imperfect surfaces, and compute the transmission loss due to mode conversion. The computation shows that the transmission loss is very large, which is due to three facts： （1） there exist slow waves in the LHM SWG, whose electric field is mainly distributed in the surface; （2） the absence of fundamental node-less modes, so the fundamental modes have a node, whose electric field is also mainly distributed in the surface, and （3） the different focusing effects of the random RHM and LHM imperfections cause the electric field to suffer from severe deformations aggravated by the electric field distribution of the guided wave and the slow wave, which of course dissipates the power carried by the guided wave more severely. Therefore, we can safely conclude that the LHM SWG is unsuitable for transmitting the fundamental modes with a node.     

MgO:Cr3+和MgO:V2+的能谱随温度移位的拟合计算

全面计入电-声子耦合导致的热移位(其中包括~2T_1贡献的单声子项,Raman项,光学支项)与热膨胀导致的热移位,对MgO:Cr~(3+)与MgO:V~(1+)的R线热移位作了理论计算,结果与热移位、热膨胀系数,高压移位、声子谱与光谱、晶体密度、弹性常数与晶格常数等大量实验数据符合得很好.进而,将完全的d~3能量矩阵对角化,得到能谱与波函数,再通过电-声子相互作用矩阵元等一系列计算,从微观上算出单声子项的参量,结果与拟合实验得到的值符合得很好.结果表明:单声子项起主导作用(导致红移),而Raman项(导致 关键词：     

波函数混合对MgO:V2+热移位的影响

根据掺稀土和过渡金属离子的晶场光谱热移位理论,光谱热移位应包括4部分贡献.利用波函数混合系数对其中作主要贡献的单声子项参量进行了理论计算,然后再对MgO:V²⁺的R线的热移位进行了拟合计算,计算结果与大量实验数据符合很好.     

三角场对红宝石光谱压力移位的影响

本文从电子径向波函数在加压下扩展的概念出发，进下考虑三角场效应，将Ｂ、Ｃ、Ｄｑ、ξ、δ等参量表示为线性压缩比ｘ的函数，我们对红宝石的光谱移位进行了理论计算，所得结果与实验符合很好，本文研究表明：三角场效应在谱线的压力移位中起着重要的作用。     

基于创新思维培育的大学物理实验教学平台建设与实践简

大学物理实验是激发学生学习大学物理兴趣、培养学生创新思维的有效手段。文中调研了国内外大学物理实验教学现状,基于地方本科院校的实际,从教学方法、教学模式和教学管理三个方面阐述了大学物理演示实验教学,着重分析了如何利用大学物理实验平台激发大学生的创新思维。     

非接触驱动方式中永磁体转动行为的实验研究

矩形永磁体与铝盘构成的非接触驱动系统中,在铝盘定速转动条件下,对通过电磁感应所驱动的磁体转动角速率、角加速度同时进行检测,发现角速度有周期性的微小波动,而角加速度在一负的最大值与正的最大值间周期性地变化,二者周期相同.从永磁体的分子环流模型出发,运用毕奥-萨伐尔定律,场叠加原理,导出了磁体绕中心转轴旋转到任意位置时,导体中的磁场分布解析表达式,依次对磁体角加速度与磁体受到的电磁驱动力矩进行定量计算,以驱动力矩与空气阻尼力矩的共同作用解释了角速度出现周期性微小波动与角加速度正负等幅变化的原因,通过与实验测试结果进行比较,验证了分析结果的正确性.     

在WGD-8A光栅光谱仪上实现变温荧光特性测量

介绍了一种在普通光栅光谱仪上实现材料荧光 温度特性测量的低成本方法,并给出了系统的详尽配置和运用该系统对部分材料荧光温度特性测量的结果.     

Field Tunable Polaritonic Band Gaps in Fibonacci Piezoelectric Superlattices

The Fibonacci piezoelectric superlattices(FPSs) with an external dc electric field is presented, in which the dc electric field can tune the bandwidth of polaritonic band gaps(PBGs) continuously and reversibly via the electrooptic effect. The absolute bandwidths of two major PBGs of the FPSs around ω= 7.5 GHz and ω = 12.5 GHz can be broadened from 0.022 GHz to 0.74 GHz and from 0.02 GHz to 0.82 GHz with the dc electric field increasing from 0 to 1.342 × 10~6 V/m, respectively. The corresponding relative bandwidths of the two major PBGs are widened from 0.28% to 9.2% and from 0.18% to 6.35%, respectively. The general mechanism for the bandwidth tunability is that the coupling strength between the lattice vibration and electromagnetic waves is capable of being altered by the dc electric field via the electro-optic effect. Thus the properties can be applied to construct microwave switchings or field tunable bulk acoustic filters.