Influence of phonon dispersion and exciton spectrum on the energy spectrum of magnetopolarons in a quantum well

An analysis is made of the influence of the spatial dispersion of LO phonons and the exciton effect on the energy spectrum of magnetopolarons in a quantum well. It is shown that in optical experiments where light is incident normally on the plane of the quantum well, a discrete spectrum of magnetopolarons is observed. Both the phonon dispersion and the Coulomb attraction of an electron and a hole may lead to a shift of the discrete magnetopolaron energy levels and additional contributions to the broadening of various levels.     

流动注射-电感耦合等离子体发射光谱法测定天然水中的钙和镁

本文采用流动注射－电感耦合等离子体发现光谱联用技术测定了天然水中的钙、镁元素。考察了试液的雾化和曝光时间及载气压力等因素对分析信号的影响。通过与气动连续进样的对比，测出了钙、镁在流动注射进样下的分散系数。本法在测定钙、镁含量高的水性时，不需对试样进行稀释处理。对五个水样中钙、镁的分析结果与EDTA络合滴定法相吻合。     

Magnetopolaron states involving confined phonons in a semiconductor quantum well

Energy splitting ΔE _res in double magnetopolaron energy spectrum in rectangular quantum wells as functions of the well width d have been calculated. We have considered in the capacity of interaction leading to resonant coupling between electrons and phonons the interaction with confined phonons and (for comparison) with bulk LO phonons. We have obtained the conditions when the interaction with bulk phonons yields correct results. Calculations for AlAs/GaAs/AlAs and AlSb/InSb/AlSb structures have been performed. Alongside the parameter ΔE _res for a polaron, whose resonant magnetic field is determined by the condition Ω=ω _L1, where Ω is the cyclotron frequency and ω _L1 is the LO phonon frequency in the quantum well (A-polaron), we have calculated ΔE _res for D-(Ω=2ω _L1) and F-polarons (Ω=3ω _L1), which is a factor of $\sqrt 2 $ and $\sqrt 3 $ , respectively, smaller than ΔE _res for the A-polaron. Since the splitting ΔE _res for the A-polaron is very large (up to 0.2?ω _L1), it is more convenient to study in experiments D-and F-polarons since their resonant magnetic fields are lower. We have predicted existence of “weak” magnetopolarons, in which the splitting is proportional to a higher power of Frölich’s coupling constant α than α ^1/2.     

光电成像系统混淆效应的定量分析

光电成像系统由于抽样产生频谱混淆。用矢量分析方法,给出了正弦图像基元的混淆表达式。具体分析了以短形光栅为例的周期目标莫尔条纹式的混淆效应,以及非周期性目标噪 声形式的混淆效应。并分别作了计算机仿真实验。     

Efficient and stable wireless power transfer based on the non-Hermitian physics

As one of the most attractive non-radiative power transfer mechanisms without cables,efficient magnetic resonance wireless power transfer(WPT)in the near field has been extensively developed in recent years,and promoted a variety of practical applications,such as mobile phones,medical implant devices and electric vehicles.However,the physical mechanism behind some key limitations of the resonance WPT,such as frequency splitting and size-dependent efficiency,is not very clear under the widely used circuit model.Here,we review the recently developed efficient and stable resonance WPT based on non-Hermitian physics,which starts from a completely different avenue(utilizing loss and gain)to introduce novel functionalities to the resonance WPT.From the perspective of non-Hermitian photonics,the coherent and incoherent effects compete and coexist in the WPT system,and the weak stable of energy transfer mainly comes from the broken phase associated with the phase transition of parity-time symmetry.Based on this basic physical framework,some optimization schemes are proposed,including using nonlinear effect,using bound states in the continuum,or resorting to the system with high-order parity-time symmetry.Moreover,the combination of non-Hermitian physics and topological photonics in multi-coil system also provides a versatile platform for long-range robust WPT with topological protection.Therefore,the non-Hermitian physics can not only exactly predict the main results of current WPT systems,but also provide new ways to solve the difficulties of previous designs.     

Three-dimensional vertical ZnO transistors with suspended top electrodes fabricated by focused ion beam technology

Three-dimensional(3D)vertical architecture transistors represent an important technological pursuit,which have distinct advantages in device integration density,operation speed,and power consumption.However,the fabrication processes of such 3D devices are complex,especially in the interconnection of electrodes.In this paper,we present a novel method which combines suspended electrodes and focused ion beam(FIB)technology to greatly simplify the electrodes interconnection in 3D devices.Based on this method,we fabricate 3D vertical core-double shell structure transistors with ZnO channel and Al₂O₃ gate-oxide both grown by atomic layer deposition.Suspended top electrodes of vertical architecture could be directly connected to planar electrodes by FIB deposited Pt nanowires,which avoid cumbersome steps in the traditional 3D structure fabrication technology.Both single pillar and arrays devices show well behaved transfer characteristics with an Ion/Ioff current ratio greater than 106 and a low threshold voltage around 0 V.The ON-current of the 2×2 pillars vertical channel transistor was 1.2μA at the gate voltage of 3 V and drain voltage of 2 V,which can be also improved by increasing the number of pillars.Our method for fabricating vertical architecture transistors can be promising for device applications with high integration density and low power consumption.     

In, Al共掺杂ZnO纳米串光电探测器的组装与研究

用化学气相沉积法合成了高密度的In, Al共掺杂ZnO纳米串, 用合成出的纳米串组装成了光电探测器. 纳米串为六角纤锌矿结构, 平均长度大约为5 μ m. 研究了光电导的机制以及光电探测器的光电特性, 包括在暗环境及紫外照射下的伏安特性、光电响应率和光电响应时间. 结果表明, 器件存在内部增益机制, 光响应时间小于0.5 s, 衰减时间约为23 s, 可用于光电探测.     

Measurement of the neutrino mass splitting and flavor mixing by MINOS

Measurements of neutrino oscillations using the disappearance of muon neutrinos from the Fermilab NuMI neutrino beam as observed by the two MINOS detectors are reported. New analysis methods have been applied to an enlarged data sample from an exposure of 7.25×10(20) protons on target. A fit to neutrino oscillations yields values of |Δm(2)|=(2.32(-0.08)(+0.12))×10(-3) eV(2) for the atmospheric mass splitting and sin(2)(2θ)>0.90 (90% C.L.) for the mixing angle. Pure neutrino decay and quantum decoherence hypotheses are excluded at 7 and 9 standard deviations, respectively.