共查询到19条相似文献，搜索用时 196 毫秒
1.
在有限深势阱模型下,求出了考虑到电子-声子相互作用情况下量子线电子基态能、概率分布和禁带宽度,以HgS/CdS量子线为例,研究了电子-声子相互作用对它们的影响.结果表明:电子-声子相互作用会降低电子基态能,在对基态能的影响中以电子与界面光学支声子相互作用的影响最大,而与界面声学支声子相互作用影响最小;电子-声子相互作用的影响和电子由势阱透入有限高势垒的概率以及禁带宽度均随量子导线半径R的减小而增大;电子-声子相互作用不改变禁带宽度随R的变化趋势,仅使其数值减小.Abstract： Amodel of cylindrical quantum wires system with one core well,one shell barrier and finite deep potential well is founded.The body phonons,interface phonons,and their couplings with electron are investigated with the help of Green's function.The equations of electronic energy spectrum and wave function are obtained considering and neglecting the electron-interface interaction,and the correction of the electron ground level,electronic distribution and band gap to the well radius are giyen.Numerical calculations on a cylindrical HgS/CdS quantum wires system have been performed.The results show that the interaction of electron-interface phonons reduces the ground level and band gap.The smaller radius,the more reduced.Electron-interface optical phonons interaction plays the most influential,electron-interface acoustic phonon interaction impact ofthe minimum.The electron-interface phonon interaction does not change with changes in the law ofthe radius,just to changethe band gap variation in quantitative.The change increases with the decreases of well radius,which consistent with experimental. 相似文献
2.
采用Lee-Low-Pines-Huybrechts变分法研究了外磁场、LO声子效应和量子点厚度对量子盘中电子-LO声子强耦合磁极化子的振动频率和qubit的影响,推导出磁极化子的振动频率λ,量子比特振荡的周期T0和电子的几率分布ρ的表达式.数值计算结果表明,磁极化子基态的振动频率大于激发态的振动频率,λ随ωc和α的增加而增大,随L的增加而减小;T0随受限强度ω0和量子盘厚度L的增加而增大,随电子-声子耦合强度α的增加而减小;ρ随ω0的增加而减小,随L的增加而振荡减小;T0和ρ随ωc和L的变化规律受ω0和α的影响显著. 相似文献
3.
本文考虑自发与压电极化引起的内建电场,基于常微分数值计算方法,求解纤锌矿GaN/Al_(0.2)Ga_(0.8)N对称和非对称应变双量子阱中,电子与空穴的薛定谔方程,得到电子与空穴的本征能量和相应本征波函数。计算结果表明:对比对称及非对称势阱情形时,得到电子(空穴)基态和第一激发态能级均随阱宽的增大而减小;且非对称双量子阱结构中波函数向另一阱中的遂穿效应有所增加,相应能级略高于对称双阱中的计算结果。同时调整左边和右边2个势阱的宽度或者单独调整某一势阱宽度时,电子(空穴)的基态和第一激发态能级均随相应阱宽的增加而减小。 相似文献
4.
采用Lee-Low-Pines变换法和Tokuda改进的线性组合算符法研究了外磁场和温度对量子盘中氢化杂质束缚强耦合磁极化子性质的影响,推导出了束缚磁极化子振动频率λ和声子平均数（N）随温度T,外磁场回旋频率ωc,电子-声子耦合强度α,介电常数比η和电子速率u的变化规律.结果表明,磁极化子的振动频率λ随电子-声子耦合强度α,介电常数比η,电子的速率u和外磁场回旋频率ω.的增加而增大,随温度T的升高和量子盘厚度L的增加而减小;磁极化子的声子平均数（N）随电子-声子耦合强度α,介电常数比η和外磁场回旋频率ωc的增加而增大,随温度T的升高和电子速率u的增加而减小,随量子盘厚度L的增加而振荡减小. 相似文献
5.
综述了近年来对抛物线性限制势量子点中强耦合双极化子和磁双极化子的部分研究工作.从抛物量子点中2个电子-声子体系的哈密顿量出发,采用Lee-Low-Pines-Huybrechts变分方法,研究了量子点中强耦合双极化子的振动频率、诱生势和有效势随电子-声子耦合强度、两电子相对距离和量子点半径的变化规律;采用Tokuda改进的线性组合算符法研究了温度和LO声子效应对强耦合双极化子的有效质量和平均声子数的影响.基于Lee-Low-Pines幺正变换,采用Pekar类型变分法研究了抛物量子点中强耦合磁双极化子的内部激发态性质,当考虑自旋和外磁场影响时,研究了二维量子点中强耦合磁双极化子基态的能量、声子平均数以及第一激发态的能量、声子平均数随量子点受限强度、介电常数比、电子-声子耦合强度和磁场的回旋共振频率的变化规律. 相似文献
6.
考虑到吸附原子与外延石墨烯原子的相互作用以及石墨烯原子的非简谐振动,研究了外延石墨烯吸附系统的电导率随温度变化的规律.以吸附在Cu和Ni基外延石墨烯上的W原子的系统为例,探讨了原子非简谐振动和吸附对电导率的影响.结果表明:①金属基外延石墨烯吸附系统的电导率随温度升高而减小,不考虑声子-电子的相互作用和吸附时,系统的电导率随温度升高而增大,但变化极小;②声子-电子相互作用引起的电导率改变量随温度升高而减小,几乎与温度成反比;③吸附引起的电导率改变量在温度不太高(低于600 K)时可以忽略,而温度较高时则随温度升高而迅速增大,温度达到1 000 K时,吸附对电导率的影响可占总量的4.35%;④原子非简谐振动对系统的电导率有重要影响.简谐近似时,电导率几乎与温度成反比.考虑到原子非简谐振动后,电导率比简谐近似的值增大,温度愈高,非简谐效应愈明显. 相似文献
7.
考虑到原子的非简谐振动和电子-声子相互作用,建立了金属基外延石墨烯的微观物理模型,用固体物理理论和方法,研究了外延石墨烯电导率随温度的变化规律,以Cu,Ni金属基底外延石墨烯为例,探讨了基底材料和原子的非简谐振动对电导率的影响.结果表明:(1)金属基外延石墨烯的电导率随温度升高而减小,其中,温度较低时时,变化较快,而温度较高时则变化很慢;它的电导率包括声子的贡献和电子的贡献两部分,其中电子的贡献部分很小,且随温度的变化也小,而声子的贡献远大于电子且随温度变化较大.(2)基底材料和原子的非简谐振动对金属基外延石墨烯的电导率有重要的影响:简谐近似下,电导率随温度的变化较小,考虑到非简谐振动,电导率随温度的变化增大.温度愈高,非简谐效应愈显著.理论结果与其他文献的值以及电学理论相近. 相似文献
8.
采用全量子理论和数值计算方法求解了旋波近似下相干态光场与耦合双原子相互作用的系统波函数,分析了原子的初始状态和原子间偶极偶极相互作用Ω对光子统计性质的影响.数值计算结果显示:原子间偶极偶极相互作用Ω对光子的超泊松分布效应无明显影响,但崩塌-回复周期却随Ω的增大而减小,近似成反比关系;系统初始状态对光子的超泊松分布效应有明显影响,而对崩塌回复周期无影响. 相似文献
9.
在EMA(Effective Mass Approximation)的理论框架下,研究了柱形量子点的能级和电子结构.计算了柱形量子点的激发态(m=1)基态(m=0)能量,并作出柱形量子点能量图;还计算了柱形量子点的电子概率密度,并作出电子概率分布图. 相似文献
10.
分析了单电子情况下InAs/InGaAs核壳结构量子点中系统总哈密顿,利用有效质量理论求解了稳态薛定谔方程；在考虑电子—声子相互作用下,利用微扰理论计算得到系统的能谱及波函数,并对其参量关系进行了分析和讨论. 相似文献
11.
T Fujisawa TH Oosterkamp van der Wiel WG BW Broer R Aguado S Tarucha LP Kouwenhoven 《Science (New York, N.Y.)》1998,282(5390):932-935
A double quantum dot device is a tunable two-level system for electronic energy states. A dc electron current was used to directly measure the rates for elastic and inelastic transitions between the two levels. For inelastic transitions, energy is exchanged with bosonic degrees of freedom in the environment. The inelastic transition rates are well described by the Einstein coefficients, relating absorption with stimulated and spontaneous emission. The most effectively coupled bosons in the specific environment of the semiconductor device used here were acoustic phonons. The experiments demonstrate the importance of vacuum fluctuations in the environment for quantum dot devices and potential design constraints for their use for preparing long-lived quantum states. 相似文献
12.
Narayanaamurti V 《Science (New York, N.Y.)》1981,213(4509):717-723
Recent experiments involving the propagation of extremely high frequency, short-wavelength acoustic phonons in semiconductors are described. Such phonons, which play an important role in thermal energy transpor and nonradiative recombination processes, can be used as sensitive microscopic probes of electronic, defect, and interface states. Experiments on phonon transmission thrugh epitaxially grown bulk material as well as thin-film superlattice structures in the semiconductor gallium arsenide are described. Such thin-film periodic structures can be used to build frequency-selective phonon filters and reflectors, which can in turn be used to manipulate phonon diagnostic beams in technologically important materials. 相似文献
13.
防止图书馆电子阅览室变“网吧”的对策 总被引：1，自引：0，他引：1
杨茜 《农业图书情报学刊》2009,21(3):211-213
将高校图书馆电子阅览室与社会网吧相比较,就防止阅览室向网吧转变,提出解决对策。使其更好的发挥本质作用。 相似文献
14.
The effect of isotopic substitution on the superconducting transition temperature, T(c), in alkali-doped C(60) has been examined. Paradoxically, it is found that a substantial decrease in T(c) with the increasing isotopic mass is possible even when the attractive interaction is not mediated by phonons but is instead of purely electronic origin. In particular, it is shown that the experimentally measured isotopic shifts are consistent with a recently proposed electronic mechanism. Further predictions are presented that can be tested by experiment. 相似文献
15.
用非限制性密度泛函方法UBP86泛函结合def2-TZVP基组获得了Ni2～6团簇的几何结构并用ELF(ElectronLocalized Function)和LOL(Localized Orbital Locator)函数对小镍团簇的电子结构进行拓扑分析.研究结果表明,除Ni2团簇外,团簇中Ni—Ni键的成键临界点不在键轴上,为弯曲键.镍团簇中Ni—Ni间的金属键为部分共价键,其价层Basin的布局数均小于1e,并且团簇中存在多个多中心价层Basin.团簇中各个化学键均强烈离域化.团簇中的单电子主要位于内层轨道,并没有参与成键. 相似文献
16.
多种淀粉颗粒的扫描电镜下的形态分析 总被引：1，自引：0，他引：1
[目的]比较分析多种淀粉颗粒的扫描电镜下的形态.[方法]利用扫描电镜对部分天然保健功能类食用淀粉进行观察,根据不同种类淀粉在扫描电镜下特征的差别,分别对每一种淀粉颗粒在扫描电镜下的形态特征进行归纳,并进行比较分析.[结果]观察发现,几种市面上宣称有保健功能类的食用淀粉如百合淀粉、葛根淀粉、桄榔淀粉、绿豆淀粉及马蹄淀粉,它们的形态分别为扁平三角形、粘连多面体型、梨形、肾形及卵圆形,与价格较低廉的日常食用淀粉如红薯淀粉、马铃薯淀粉、木薯淀粉、豌豆淀粉、小麦淀粉和玉米淀粉的形态及大小仍是有所区别,在扫描电镜下观察能较直观地反映出差别.[结论]研究可为天然保健功能类食用淀粉的鉴别提供参考依据. 相似文献
17.
Kroes GJ 《Science (New York, N.Y.)》2008,321(5890):794-797
Theorists have recently made substantial progress in simulating reactive molecule-metal surface scattering but still face major challenges. The grand challenge is to develop an approach that enables accurate predictive calculations of reactions involving electronically excited states with potential curve crossings. This challenge is all the more daunting because collisions involving molecules heavier than H2 may be accompanied by substantial energy exchange with the surface vibrations (phonons), and because an electronic structure approach that allows molecule-surface interaction energies to be computed with chemical accuracy (1 kilocalorie per mole) is not yet available even for the electronic ground state of molecule-metal surface systems. 相似文献
18.
为探讨烟叶腺毛形态与功能的关系提供部分依据,采用扫描电镜的方法对烟草栽培品种K346叶片表面的腺毛形态和细微结构进行观察。烟草叶片表面长柄腺毛柄部一般有几个比较明显的长柱型节;短柄腺毛的柄部由一个较短的柱形柄构成,短柄腺毛一般较为粗短;烟草腺毛头部的形态比较复杂,是腺毛分泌功能的主要部位,长柄腺毛和短柄腺毛的头部相对于其紧邻的柄部显得膨大,特别是短柄腺毛头部膨大明显,四周呈皱褶状,有明显的凹陷和凸起。烟草叶片表面腺毛形态与其分泌功能有关,腺毛的细微结构可以为其结构与功能的研究提供部分依据。 相似文献
19.
Deheer WA Bacsa WS Châtelain A Gerfin T Humphrey-Baker R Forro L Ugarte D 《Science (New York, N.Y.)》1995,268(5212):845-847
Carbon nanotube material can now be produced in macroscopic quantities. However, the raw material has a disordered structure, which restricts investigations of both the properties and applications of the nanotubes. A method has been developed to produce thin films of aligned carbon nanotubes. The tubes can be aligned either parallel or perpendicular to the surface, as verified by scanning electron microscopy. The parallel aligned surfaces are birefringent, reflecting differences in the dielectric function along and normal to the tubes. The electrical resistivities are anisotropic as well, being smaller along the tubes than perpendicular to them, because of corresponding differences in the electronic transport properties. 相似文献