聚乙炔中双激子和两个单激子的稳态性质

在Su-Schrieffer-Heeger(SSH)模型基础上,计入长程电子关联的影响,研究聚乙炔分子链中双激子态与2个单激子态的稳态性质,比较不同关联强度下激子的晶格位形、能级、电荷密度波、自旋密度波以及吸收谱线。结果表明:零电子关联下分子链中的2个单激子不能稳定存在;激子半径均随着关联强度的增加而减小;与双激子的2个能级精细结构相比,2个单激子的能隙出现4个精细结构;2类激子的电荷密度波、自旋密度波与吸收谱线均随关联强度变化,并呈现显著区别。以上结果为区分分子链中2类激子的行为提供了依据,结果显示在激子行为中必须考虑电子与其的关联性。

量子阱单激子光增益实现超低阈值连续波激光

胶质纳米晶光增益材料对于开发新一代的高效激光器前景巨大.采用外延生长法制备原子尺寸厚度的Ⅱ型CdSe/CdTe复合纳米片,研究该异质结构的光学性质及其对应的电荷动力学过程,以此探讨其光增益性能及激光应用潜能.光谱结果表明,Ⅱ型纳米片有效的电子与空穴分离结构使其表现出较大的斯托克斯位移(ΔS=100 meV)和较强的激子-激子库伦排斥力(ΔXX=50 meV).ΔS和ΔXX的协同效应使"激子-双激子"吸收能相比单激子发射能提高了约150meV,打破了一般纳米晶结构中两者的简并关系,这将有效抑制光吸收损失并促进单激子光增益.单激子光增益机制下该纳米片较长的单激子寿命(τx=394 ns)使连续激光泵浦的理论功率阈值低至12 W/cm^2,这为开发实用性更强的、超低阈值的连续波激光器提供可能.

Single Event Transients of Operational Amplifier and Optocoupler

The single event transient effects of the operational amplifier LM124J and the optocoupler HCPL 5231 are investigated by a pulsed laser test facility. The relation of transient pulse shape to pulsed laser equivalent LET is tested,the sensitive areas of the SET effects are identified in voltage follower application mode of LM124J, and the mechanism is initially analyzed. The transient amplitude and duration of HCPL5231 at various equivalent LET are examined,and the SET cross-section is measured. The results of our test and heavy ion experimental data coincide closely,indicating that a pulsed laser test facility is a valid tool for single event effect evaluation.

A Single Mode980 nm In Ga As/Ga As/Al Ga As Large Optical Cavity Quantum Well Laser with Low Vertical Divergence Angle

To achieve high optical power as well as low vertical divergence angle,a new kind of optim ized large opti- cal cavity (L OC) structure is applied to a ridge waveguide 980 nm In Ga As/ Ga As/ Al Ga As m ulti- quantum well laser.The optical power density in the waveguide is successfully reduced.The maxim um output power is more than 40 0 m W with a slope efficiency of 0 .89W/ A and the far- field vertical divergence angle is lowered to 2 3°.

Laser Controlling Wavepacket Trains of a Paul Trapped Ion

We have studied the quantum and classical motions of a single Paul trapped ion interacting with a timeperiodic laser field. By using the test-function method, we construct n exact solutions of quantum dynamics that describe the generalized squeezed coherent states with the expectation orbits being the corresponding classical ones. The spacetime evolutions of the exact probability densities show some wavepacket trains. It is demonstrated analytically that by adjusting the laser intensity and frequency, we can control the center motions of the wavepacket trains. We also discuss the other physical properties such as the expectation value of energy, the widths and heights of the wavepackets, and the resonance loss of stability.

Clinical study of co-treatment with DC-CIK cells for advanced solid carcinomas

Objective： The aim of this study was to observe the therapeutic effect of cytokine induced killer （CIK） cells in combination with dendritic cells （DCs） on advanced solid carcinoma patients. Methods： Isolated peripheral blood mononuclear cells （PBMCs） from 110 advanced solid tumor patients. Added granulocyte-macrophage colony-stimulating factor （GM-CSF）, tumor necrosis factor-a （TNF-a） and interleukin-4 （IL-4） to adherent cells to induce DCs, and sensitized DCs with antigens of autologous tumor cells or extrinsic tumor cell lines. Cultured suspending cells with interferon-y （IFN-y）, interleukin-2 （IL-2） and CD3 monoclonal antibody （CD3 McAb） to prepare CIK cells, then co-cultured with DCs. After analyzing the phenotype and checking tumor markers and immune function, the autologous CIK cells and DCs were transfused into the cancer patients. Results： Forty-two patients with measurable nidus, 2 achieved complete remission （CR）, 9 partial remission （PR） and 15 stable disease （SD）, while 37 patients with immeasurable nidus, 25 had efficient response. The tumor markers and immune function both improved significantly compared with those before treatment. Conclusion： DCs and CIK cells combinational treatment is safe and effective on advanced solid carcinoma and provide a new and efficacious immunity therapeutic methods for the cancer patients.

An Analytical Solution to the Model for Single Three-Level Trapped Ion Driven by External Fields

The interaction of a single three-level trapped ion with two laser beams has been studied theoretically. With application of two successive unitary transformations, an analytical solution to this quantum system has been obtained.

Effect of the interfacial electric field on the HER on Pt(111)modified with iron adatoms in alkaline media

The study of the hydrogen evolution reaction(HER)aimed to reach a deeper understanding of the parameters that control the rate of this reaction is of great importance given the technical relevance of hydrogen production as an energy vector in the so-called hydrogen economy.In previous works,laser-induced temperature jump(LITJ)experiments on Pt(111)modified with Ni(OH)_(2)in alkaline media have revealed the importance of the interfacial electric field in the rate of the HER.It was hypothesised that small amounts of Ni(OH)_(2)cause a decrease of the electric field because of a negative shift of the pzfc toward the onset of the hydrogen evolution.In this work,to test the validity of this hypothesis,the study has been extended to Pt(111)surfaces modified with Fe(OH)_(2).The modified surfaces have been studied voltammetrically,and the voltammetric charges have been analysed.The voltammograms show a peak in the hydrogen evolution region that suggest the transformation in the adlayer from Fe(II)to Fe(0).In agreement with the coulometric analysis,the voltammetric features in the OH adsorption region would be related with the oxidation to the+3 valence state.The results obtained with LITJ method reflect the existence of a strong interaction of the Fe oxophilic species with the water molecules,shifting the potential of maximum entropy away from the onset of the HER.Hence,the most catalytic surface is the one with the lowest Fe coverage.

Solitary Excitations of Dipolar Bosons in Optical Lattice under Magnetic Fields

We obtain the multisolitary solutions of the extended Bose-Hubbard model which describes dipolar Bose- Einstein condensates in optical lattices under time-dependent magnetic fields, and indicate that the nonlinearity is due to both on-site short-range interactions and also （long-range） dipole-dipole interactions which can act between neighboring sites. The discrete breathers as nonlinear excitations are always oscillatory in time and can also be spatially localized, while the oscillatory frequencies are determined by an external field. We show that these excitations will be observable and discuss how the parameters can be tuned in future experiments.

One-Step Generation of Scalable Multiparticle Entanglement for Hot Ions Driven by a Standing-Wave Laser

An alternative scheme is proposed for one-step generation of multiparticle cluster state with trapped ionsin thermal motion.In this scheme,the ions are simultaneously illuminated by a standing-wave laser tuned to the carrier.During the operations,the vibrational mode is virtually excited,thus the quantum operations are insensitive to theheating.It is shown that the high fidelity multiparticle entanglement could be generated in just one step even includingthe small fluctuations of parameters.In addition,the ion does not need to be exactly positioned at the node of thestanding wave,which is also important from the viewpoint of experiment.

InAs单量子点中级联辐射光子的关联测量

利用分子束外延生长InAs单量子点样品,温度为5K时,测量了单量子点中单、双激子自发辐射的荧光(PL)光谱.研究了单、双激子发光强度随激发功率的变化及对应发光峰的偏振特性和精细结构劈裂.基于Hanbury-Brown Twiss(HBT)实验,测量了单、双激子间发光光谱的关联函数,证实了其发光过程为级联发射过程.

The effect of the substrate on the Raman and photoluminescence emission of single-layer MoS2

We quantitatively study the Raman and photoluminescence （PL） emission from single-layer molybdenum disulfide （MoS2） on dielectric （SiO2, hexagonal boron nitride, mica and the polymeric dielectric Gel-Film） and conducting substrates （Au and few-layer graphene）. We find that the substrate can affect the Raman and PL emission in a twofold manner. First, the absorption and emission intensities are strongly modulated by the constructive/destructive interference within the different substrates. Second, the position of the Alg Raman mode peak and the spectral weight between neutral and charged excitons in the PL spectra are modified by the substrate. We attribute this effect to substrate-induced changes in the doping level and in the decay rates of the excitonic transitions. Our results provide a method to quantitatively study the Raman and PL emission from MoSa-based vertical heterostructures and represent the first step in ad hoc tuning the PL emission of 1L MoS2 by selecting the proper substrate.

Synthesis,photophysical properties and TD-DFT calculation of four two-photon absorbing triphenylamine derivatives

In this study,linear absorption,single-photon excited fluorescence,fluorescence quantum yields,fluorescence lifetime and two-photon excited fluorescence of a series of triphenylamine derivatives (L1,L2,L3 and L4) have been measured.L1 and L3 are D--A type dyes,while L2 and L4 are D--D--A type dyes (D=donor,A=acceptor).The investigated compounds consist of triphenylamine-bearing donor-substituted and/or systematically extended-conjugated length,which are designed to gain insight into the effect of the ethoxyl unit and-linkage length on the linear and nonlinear optical properties.The influence of solvent polarity on the photophysical properties was investigated.Employing time-dependent density functional theory (TD-DFT) calculations,the structure-property relationships are discussed.

A single stage EEHG at SXFEL for narrow-bandwidth soft X-ray generation

The echo-enabled harmonic generation （EEHG） scheme holds promising prospects for efficiently generat- ing intense coherent radiation at very high harmonics of the initial seed laser. In this paper, we study the feasibility of operating the Shanghai X-ray free-electron laser test facility with a single stage EEHG setup. With a combina- tion of existing numerical codes, start-to-end simulations considering various three-dimensional effects have been carried out to show the possible performance of the EEHG FEL. Simulation results demonstrate that a single stage EEHG can generate high power soft X-ray radiation pulses with narrow bandwidth directly from UV seed lasers. With the help of the harmonic lasing technique or upgraded linac, we also show the possibility of generating coherent soft X-ray radiation in the ＂water window＂ with a single stage EEHG.

Efficient Excitation of a Symmetric Collective Atomic State with a Single-Photon Through Dipole Blockade

In the famous quantum communication scheme developed by Duan et al.[L.M.Duan,M.D.Lukin,J.I.Cirac,and P.Zoller,Nature(London) 414(2001) 413],the probability of successful generating a symmetric collective atomic state with a single-photon emitted have to be far smaller than 1 to obtain an acceptable entangled state.Based on strong dipole-dipole interaction between two Rydberg atoms,two simultaneous excitations in an atomic ensemble are greatly suppressed,which makes it possible to excite a mesoscopic cold atomic ensemble into a near-ideal singly-excited symmetric collective state accompanied by a signal-photon with near unity success probability.

Nanoplasmonic colloidal suspensions for the enhance-ment of the luminescent emission from single-walled carbon nanotubes

Aiming to enhance the luminescence yield of carbon nanotubes, we introduce a new class of hybrid nanoplasmonic colloidal systems （π-hybrids）. Nanotubes dispersed in gold nanorod colloidal suspensions yield hybrid structures exhibiting enhanced luminescence up to a factor of 20. The novelty of the proposed enhancement mechanism relies on including metal proximity effects in addition to its localized surface plasmons. This simple, robust and flexible technique enhances the luminescence of nanotubes with chiralities whose enhancement has never reported before, for example the （8,4） tube.