CdSe和ZnO量子点的拉曼光谱研究

本文介绍了用拉曼光谱研究CdSe和ZnO两种Ⅱ Ⅳ族量子点材料的结果,对拉曼峰进行了指认。观察到的光学声子峰位的移动被认为是由量子限制效应引起。     

用高温超导模拟研制磁场高均匀度回旋管

磁场高均匀度的低温超导磁体系统已经取得了广泛的应用，在许多领域发挥着重要的作用。随着低温技术和超导技术的发展，用高温超导材料制作高均匀度的超导磁体成为可能。因此，我们用高温超导材料模拟制作了磁场高均匀度回旋管。     

Origin of the 420 nm Absorption Band and Effect of Doping Fluorine in PbWO4 Crystals

The electronic structures for three types of PbW04 (PWO) crystals, the perfect PWO, the PWO containing lead vacancy (PWO-Vpb) and fluorine doped PWO crystal (F^-：PWO), are systematically studied within the framework of density functional theory. The computational results show that the Pb 6s state situates below the valence band so that Pb^2 ions are unable to trap holes forming Pb^3 or Pb^4 to compensate for VPb^2-. The hole-trappers in PWO-Vpb are O^2- ions. Two of the longer-bond O^2- ions share a hole forming O2^3-, and four of the longer-bond oxygen ions trap two holes forming an associated color centre [O2^3--Vpb-O2^3-], which may be the origin of the 42Onto absorption band. It is also concluded that the doping of F^- would reduce the band gap and F^- ions substituting for O^2- can effectively restrict the formation of [O2^3--Vpb-O2^3-] and weaken the 42Onm absorption band and hence enhance the scintillation property of PWO.     

Singlet-Triplet Transition in Quantum Dots Confined by Triangular and Bowl-Like Potentials： the Effect of Electric Fields

We theoretically investigate the energy spectra of two-electron two-dimensional （2e 2D） quantum dots （QDs） confined by triangular potentials and bowl-like potentials in a magnetic field by exact diagonalization in the framework of effective mass theory. An in-plane electric field is found to contribute to the singlet-triplet transition of the ground state of the 2e 2D QDs confined by triangular or bowl-like potentials in a perpendicular magnetic field. The stronger the in-plane electric field, the smaller the magnetic field for the total spin of the ground states in the dot systems to change from S = 0 to S = 1. However, the influence of an in-plane electric field on the singlettriplet transition of the ground state of two electrons in a triangular QD modulated by a perpendicular magnetic field is quite small because the triangular potential just deviates from the harmonic potential well slightly. We find that the strength of the perpendicular magnetic field needed for the spin singlet-triplet transition of the ground state of the QD confined by a bowl-like potential is reduced drastically by applying an in-plane electric field.     

Raman properties embeddedof GaSb nanoparticlesin SiO2 films

The Raman shifts of nanocrystalline GaSb excited by an Ar^ ion laser at wavelengths 514.5, 496.5, 488.0, 476.5,and 457.9nm are studied by an SPEX-1403 laser Raman spectrometer respectively, and they are explained by phonon confinement, tensile stress, resonant Raman scattering and quantum size effects. The Stokes and anti-Stokes Raman spectra of GaSb nanocrystals strongly support the Raman feature of GaSb nanocrystals. The calculated optical spectra compare well with experimental data on Raman scattering GaSb nanocrystals.     

浅谈家用吊扇的调速方法

家用吊扇的核心部分是单相异步电动机,此绕组如图1,有一主绕组(工作绕组)与一串联电容器C的副绕组(启动绕组)相并联.这样做可使二绕组的电流在相位上相差90°,从而形成旋转磁场.转子的转动过程与三相异步电动机相似.     

浅淡多普勒效应

列车进站时，我们听到汽笛声不仅越来越大，而且音调变高；列车离去时，汽笛声不仅越来越小，而且音调变低．反之，若声源未动而观察者运动，或者声源和观察者同时在相对运动，也会发生观测频率与波源频率不一致的现象．由于波源或观察者的运动而出现观测频率与波     

用激光吹气注入高Z杂质使HL-1M装置放电有效地安全终止的研究

现在国际上大装置纷纷发现破裂放电而导致电流突然中止造成装置遭受重大的危害，因为能量熄灭阶段存在强烈的热通量，而且在电流熄灭阶段中产生强烈的逃逸电子，使得第一壁材料可运行的时间大大缩减；同时在真空器壁上产生很强的电磁力。所以，必须在大装置上建立一种避免和软化能量衰竭与电流衰竭，并且控制预计的放电破裂或突然终止放电的措施。