介质阻挡放电中四边形发光斑图的时空结构

为了研究介质阻挡放电(dielectric barrier discharge,DBD)中四边形发光斑图的时空结构,采用高速相机,首次在外加电压的半个周期内,对此斑图进行了时空分辨研究。在空气-氩气介质阻挡放电中,随着外加电压的增加,放电丝的分布经历了随机放电丝—六边形斑图—四边形斑图—混沌的转变过程。经长时间观察发现,四边形斑图非常稳定。在外加电压的每半个周期内,四边形斑图相应的放电电流由2个明显的脉冲组成。实验采用高速相机,分别在2个电流脉冲时间内对放电过程进行了拍照,结果发现每个电流脉冲分别对应1套稀疏的四边形子点阵发光斑图,2套子点阵互相嵌套形成所观察到的四边形发光斑图。

谈谈分子运动的辩证法

物体的机械运动通过摩擦和碰撞等形式转化为分子的运动。分子运动是物理学研究的重要内容。它是物体不同的聚集状态和热现象的微观基础。恩格斯曾经指出:'一切运动都存在于吸引和排斥的相互作用之中'。

Texture Analysis of Damascene Copper Interconnects

Texture and grain boundary character distribution of Cu interconnects with different line width for as-deposited and annealed conditions were measured by EBSD. All specimens appear mixed texture and （111） texture is the dominate component.As-deposited interconnects undergo the phenomenon of self-annealing at RT,in which some abnormally large grains are found. Lower aspect ratio of lines and anneal treatment procured larger grains and stronger （111） texture. Meanwhile, the intensity proportion of other textures with lower strain energy to （111） texture is decreased. As-deposited specimens reveal （111）（112？ and （111） （231） components, （111） （110） component appeared and （111） （112？ and （111） （231） components were developed during the annealing process. High angle boundaries are dominant in all specimens, boundaries with a misorientation of 55°-60° and ∑3 ones in higher proportion, followed by lower boundaries with a misorientation of 35°-40° and 29 boundaries. As the aspect ratio of lines and anneal treatment increase,there is a gradual in- crement in ∑3 boundaries and a decrease in ∑9 boundaries.

A Novel Method to Produce Quantum Dots

A novel method to produce quantum dots on Si substrate using AAO template and UV pulsed laser deposition technique was proposed and tested.AAO template fabricated by two-step method was put in front of si single crystal substrate.The luminescence target material La_(0.95)Eu_(0.05)BaB_(9)O_(16)was ablated by pulsed UV laser(248nm),and passed through the holes in AAO template,and was deposited on the substrate.Both Raman and luminescence spectra were measured to find the difference between the bulk target and the dots materials.

Coupled Modified Korteweg-de Vries Lattice in （2＋1） Dimensions and Soliton Solutions

The coupled semi-discrete modified Korteweg-de Vries equation in （2＋1）-dimensions is proposed, it is shown that it, can be decomposed into two （1＋1）-dimensional differential-difference equations belonging to mKdV lattice hierarchy by considering a discrete isospeetral problem. A Darboux transformation is set up for the resulting （2＋1）- dimensional lattice soliton equation with the help of gauge transformations of Lax pairs. As an illustration by example, the soliton solutions of the mKdV lartice equation in （2＋1）-dimensions are explicitly given,

Energy Spectrum of Two-Component Bose-Einstein Condensates in Optical Lattices

With the method of Green's function, we investigate the energy spectra of two-component ultracold bosonic atoms in optical lattices. We End that there are two energy bands for each component. The critical condition of the superfluid-Mott insulator phase transition is determined by the energy band structure. We also find that the nearest neighboring and on-site interactions fail to change the structure of energy bands, but shift the energy bands only. According to the conditions of the phase transitions, three stable superfluid and Mott insulating phases can be found by adjusting the experiment parameters. We also discuss the possibility of observing these new phases and their transitions in further experiments.

Ionization Potentials and Quantum Defects of 1s^2np^2p Rydberg States of Lithium Atom

Abstract In this work, ionization potentials and quantum effects of ls^2 np^2 P Rydberg states of lithium are calculated based on the calibrated quantum defect function. Energy levels and quantum defects for ls^2np^2P bound states and their adjacent continuum states are calculated with the R-matrix theory, and then the quantum defect function of the ls^2np （n ≥ 7） channel is obtained, which varies smoothly with the energy based on the quantum defect theory. The accurate quantum defect of the ls^2 7p^2P state derived from the experimental data is used to calibrate the original quantum defect function. The new function is used to calculate ionization potentials and quantum effects of ls^2np ^2P （n ≥ 7） Rydberg states. Present calculations are in agreement with recent experimental data in whole.

Near-Infrared emission from PbS Quantum Dots in polymer matrix

PbS quantum dots were prepared in the aqueous medium from readily available precursors. The shape of the particles isapproximately spherical, and the average particle size observed from HRTEM image was 7-8 nm. We applied PbS quantumdots and PMMA polymer to fabricate PbS quantum dots-PMMA composites, and investigate the photoluminescence PbSquantum dots in PMMA matrix with different mass ratio. PbS quantum dots in PMMA matrix have broad emission be-tween 900 nm and 1 500 nm and photoluminescence peak at 1 179 nm. Additionally, the photoluminescence intensityincreases with increasing the dopant concentration. PbS quantum dots-PMMA polymer composites can be potentially usedfor polymer optical fiber and electroluminescence (EL) in optical communication.

Design and fabrication of sub-μs silicon-on-insulator thermo-optic 4×4 switch matrix

A rearrangeable nonblocking silicon-on-insulator-based thermo-optic 4x4 switch matrix with spot size converters （SSCs） and a new driving circuit are designed and fabricated. The introduction of a spot size converter （SSC） has decreased the insertion loss to less than 10dB and the new driving circuit has improved the response speed to less than l^s.

Negative Trions Trapped by a Spherical Parabolic Quantum Dot

In this paper, a negatively charged exciton trapped by a spherical parabolic quantum dot has been investigated. The energy spectra of low-lying states are calculated by means of matrix diagonalization. The important feature of the low-lying states of the negatively charged excitons in a spherical quantum dot is obtained via an analysis of the energy spectra.

A resonator mode in linear arrays of silver spheres and cylinders

A transversal mode with zero group velocity and non-zero phase velocity that can exist in chains of silver nano- spheres in the optical frequency range was theoretically studied. It is shown that the external source radiating a narrow-band non-monochromatic signal can excite in the chain a mixture of standing and slowly travelling waves. The standing wave com- ponent (named as resonator mode) is strongly dominating. The physical reason of such a regime is a sign-varying distribution of power flux over the cross section of the chain. This situation is similar to the scenario of the propagation of a wave along the boundary between the right-handed and left-handed media where the spatial distribution of the light intensity is vortex. However, in the present case there is no boundary between media and the boundary between the positive and negative power fluxes is a cylindric tube in free space whose axis is the axis of the chain.

Probability of Deuteron-Plasmon Fusion at Room Temperature within Micro-cracks of Crystalline Lattices with Deuterium Loading

This communication seeks to demonstrate that, at room temperature, the deformation of the crystalline lattice can influence the process of interaction of deuterons introduced within it. Calculations of this probability, in fact, showed an increase of at least 2-3 orders of magnitude with respect to the probability of fusion on the surface of the lattice. These phenomena open the way to the theoretical hypothesis of a kind of chain reaction, as a result of the deuterium loading and catalysed by micro-cracks formed in the structure by micro-explosions, can favour the process.

A Negative Donor D^- in a Magnetic Field

Using the method of numerical matrix diagonalization within the effective-mass approximation, we investigated a D^--center quantum dot system subjected to a Gaussian potential confinement. We obtain the dependence of binding energies of the ground-states of the D^--center on the depth of Gaussian potential and the magnetic field strength. The result shows clearly that the binding energies of the ground-states of the D^--center are rather sensitive to the depth of potential and the strength of magnetic field.

Photoluminescence Properties of Si_(1-x)Ge_x/Si Strained Layer Structures

The investigation on optical properties of Si1-xGex/Si strained layer structures has been carried out actively in recent years. The photoluminescence has become a brisker subject in the studies of its various optical properties. A research development on photoluminescence properties of some new Si1-x Gex/Si strained layer structures is introduced.

Density of States in Two-Dimensional Square Lattices Around Half Filling with Strong Impurities

We calculate the lowest-order quantum-interference correction to the density of states (DOS) of weakly-disordered two-dimensional (2D) tight-binding square lattices around half filling. The impurities are assumed to be randomly distributed on small fractions of the sites, and have a-strong potential yielding a unitary-limit scattering. In addition to the usual diffusive modes in the retarded-advanced channel, there appear diffusive pi modes in the retarded-retarded (or advanced-advanced) channel due to the existence of particle-hole symmetry. It is found that the pi-mode diffuson gives rise to a logarithmic suppression to the DOS near the band center, which prevails over the positive correction contributed by pi-mode cooperon. As a result, the DOS is subject to a negative total correction. This result is qualitatively different from the divergent behavior of the DOS at the band center predicted previously for disordered 2D two-sublattice models with the particle-hole symmetry.

Binding Energies of D^- Centers Trapped by a Quantum Dot in a Magnetic Field

A investigation of the properties of the bound states of D^- centers confined in a parabolic quantum dot has been performed for the case with the presence of a perpendicular magnetic field. Calculations are carried out by using the method of numerical diagonalization of Hamiltonian matrix within the effective-mass approximation. The binding energies of the ground and some bound-excited states are obtained as a function of the applied magnetic field strength. Detailed calculations of the binding energies for a number of low-lying states show that for field strength less than B = 2.1 T, the D center confined in a quantum dot possesses two bound states, for 2.1 〈 B 〈 2.4 T, there exist three bound states, etc. Further relevant characteristics of the D- center quantum dots in magnetic fields are provided.

电子管

N2003-07854-1 0322320新碳毫微电子管物质的研制=新物质创制[汇,日]/筱原久典//信学技报,Vol.100,No.683.—1～4(L)N2003-07854-5 0322321基于气相热分解法的碳毫微电子管、毫微光纤的生成及其在高性能器件中的应用=气相热分解法生成高性能应用[汇,日]/远藤守信//信学技报,Vol.100,No.683.—5～11(L)

IrTi合金晶格动力学的第一性原理研究

利用密度泛函理论的平面波赝势方法研究了IrTi合金的晶格动力学行为.声子谱计算表明四方(L10)结构动力学不稳定,通过冷冻不稳定声子模式,发现IrTi会发生从四方(Ll_0)到正交的结构相变.进一步分析软模对应的原子振动,得到了具有正交对称性,空间群为Cmmm,相对于四方(Ll_0)相能量更低、更稳定的结构.这种正交新相(Cmmm)弹性稳定和动力学稳定,而且其结构参数与实验上观察到的低温结构有限的晶格参数相符合,表明IrTi合金的低温相是正交结构(Cmmm).从理论上肯定了IrTi合金立方到四方再到正交的相变机制,解决了实验上关于相变机制和低温相结构形式的争议.

Long-range adiabatic quantum state transfer through a linear array of quantum dots

We introduce an adiabatic long-range quantum communication proposal based on a quantum dot array.By adiabatically varying the external gate voltage applied on the system,the quantum information encoded in the electron can be transported from one end dot to another.We numerically solve the schr dinger equation for a system with a given number of quantum dots.It is shown that this scheme is a simple and efficient protocol to coherently manipulate the population transfer under suitable gate pulses.The dependence of the energy gap and the transfer time on system parameters is analyzed and shown numerically.We also investigate the adiabatic passage in a more realistic system in the presence of inevitable fabrication imperfections.This method provides guidance for future realizations of adiabatic quantum state transfer in experiments.

The reflection and interference of electrons at the interface of superlattice

A new algorithm for the calculation of the electron state of superlattice was proposed. From the electron wave point of view, the reflection and interference of electron wave at the interface of superlattice were accounted for and the electron states of the superlattice were discussed. The electron energy levels calculated using this algorithm are in good agreement with experimental results.