bluuebunny/crossref_metadata_2025 huggingface dataset:
Lattice constant deviation from Vegard's law in GeSn alloys
Authors: Su Shao-Jian  , Cheng Bu-Wen  , Xue Chun-Lai  , Zhang Dong-Liang  , Zhang Guang-Ze  , Wang Qi-Ming  ,   State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
Published: December 2020

Three layers of fully-strained Ge1-xSnx alloys with x=0.025, 0.052, and 0.078 from bottom to up are grown on a Si (001) substrate using a high-quality, strain-relaxed Ge thin film as buffer layer. Five relaxed Ge1-xSnx samples (x=0.005, 0.016, 0.044, 0.070, and 0.155) are grown directly on Si (001) substrates as well. The compositions and lattice constants of the Ge1-xSnx alloys are measured by Rutherford backscattering spectra, high-resolution X-ray diffractions, and X-ray reciprocal space mapping. The experimental results reveal a quite large positive deviation from Vegard's law with a bowing parameter b=0.211 Å.
Research on the total dose effects for domestic VDMOS devices used in satellite
Authors: Gao Bo  , Liu Gang  , Wang Li-Xin  , Han Zheng-Sheng  , Zhang Yan-Fei  , Wang Chun-Ling  , Wen Jing-Chao  ,   Institute of Microelectronics Chinese Academy of Sciences, Beijing 100029, China
Published: December 2020

Total dose effects of domestic VDMOS devices used in satellite under different bias conditions are investigated. The dependences of the typical electrical parameters such as threshold voltage, breakdown voltage, on-state resistance, and leakage current on total dose are discussed. The experimental results show that the electrical parameters of the irradiated domestic VDMOS devices fulfill the design requirements. These devices also meet the work demand in a complex ionizing total dose irradiation environment. In addition, our experimental results are meaningful and important for further improving the design and the process of the others types of domestic radiation hardened VDMOS devices.
Helium effect on the stability of the interface of Cu/W nanomultilayer
Authors: Liu Wang  , Wu Qi-Qi  , Chen Shun-Li  , Zhu Jing-Jun  , An Zhu  , Wang Yuan  ,   Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064, China
Published: December 2020

In this paper, Cu/W nanomultilayers with different modulation periods are prepared in pure Ar and mixing atmosphere (He and Ar) by radio frequency magnetron sputtering method. The helium content, cross-section morphology and phase structure of Cu/W nanomultilayer are characterized by EPBS, SEM and XRD, repectively. The results show that the stable interface of the nanomultilayer is the prerequisite for resisting and the guarantee against the damage of helium. The nanomultilayer can suppress the growth of helium bubbles under the appropriate modulation.
Transport properties of nonlinear chains with random dimer nonlinearity parameters
Authors: Hu Dong-Sheng  , Zhang Yan-Ling  , Yin Xiao-Gang  , Xu Jiang  ,   College of Science, Nanjing University of Aeronautics and Astronautics, Nanjing 211100, China;,   Department of Material Science and Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 211100, China
Published: December 2020

By using the recursion relation of discrete Schrödinger equation we investigate the transport properties of nonlinear chains with random dimer nonlinearity parameters. It is shown that there is a resonance state, which is just the product of the nonlinearity and the square of the incident wave amplitude modulus. The transmission coefficients are calculated in two conditions. One is that the transmission wave amplitude is a certain value, the other is that the incident wave amplitude modulus is a certain value. There are obvious differences in non-resonant states between the two kinds of conditions. The transmission is a single value function of the electronic energy for the former. However, it will be multi-stability for the latter. It is pointed out that the influence of the nonlinearity parameters on the transport properties can be exactly reflected only when the modulus of incident wave is set to be a certain value.
First principles study of the elastic, electronic and optical properties of MgS under pressure
Authors: Chen Zhong-Jun  ,   Department of Applied Physics, University of Electronic Science and Technology of China, Chengdu 610054, China
Published: December 2020

The structural, elastic, electronic and optical properties of MgS B2 crystal under high pressure are studied by accurate first-principles plane wave pseudo-potential method which is based on the density functional theory. Our results show that the conduction band of the structure has a shift tendency toward higher energy, and the valence band has a shift tendency toward lower energy under high pressure. We analyze the optical properties associated with the partial density of states and the shift of energy level under high pressure. At the same time, the absorption spectrum of the MgS B2 crystal has an evident blue shift.
Effects of the improved hetero-material-gate approach on sub-micron silicon carbide metal-semiconductor field-effect transistor
Authors: Song Kun  , Chai Chang-Chun  , Yang Yin-Tang  , Jia Hu-Jun  , Chen Bin  , Ma Zhen-Yang  ,   Key Laboratory of Wide Band-Gap Semiconductor Materials and Devices of the Ministry of Education, School of Microelectronics, Xidian University, Xi'an 710071, China
Published: December 2020

Based on the device operation mechanism and physical model, effects of the improved hetero-material-gate (HMG) approach on deep sub-micron silicon carbide (SiC) metal-semiconductor field-effect transistor (MESFET) are analyzed. By comparing with the conventional MESFET, it is shown that the improved HMG approach induces a multi-stepped distribution of the potential in the channel, leading to an enhanced electric field at the source. Meanwhile, the position of the maximum of the channel potential is changed to the drain side compared with the dual-material-gate (DMG) device, thus the carriers in the channel are accelerated more efficiently and the variation of potential caused by drain voltage is eliminated to a certain degree, resulting in a better restraint in short-channel effect. Also, different technological parameters are designed to study the dependence of the device performance and an optimization plan is obtained, leading to a decreased sub-threshold swing. In addition, asymmetric gate structures are designed for high power application, achieving an improved distribution of the electric field at the gate edge and an enhanced breakdown voltage of the small scale device.
The evolution of three-body entanglement in the system of atoms interacting with coupled cavities
Authors: Lu Dao-Ming  ,   Department of Electronic Engineering, Wuyi University, Wuyishan 354300, China
Published: December 2020

In this paper we consider the situation that four identical two-level atoms are separately trapped in coupled single-mode optical cavities and each atom resonantly interacts with cavity via a one-photon hopping. The three-body entanglement dynamics in each cavity is studied. The influences of atom-cavity coupling constant on the three-body entanglement are discussed. The results obtained using the numerical method show that the three-body entanglement displays the collapse-revival phenomena when atom-cavity coupling constant is larger than a fixed value. On the other hand, the three-body entanglement is the result of the coherent superposition of the two-body entanglements.
On the schemes of cavity photon elimination in circuit-quantum electrodynamics systems
Authors: Meng Jian-Yu  , Wang Pei-Yue  , Feng Wei  , Yang Guo-Jian  , Li Xin-Qi  ,   Department of Physics, Beijing Normal University, Beijing 100875, China
Published: December 2020

The solid-state superconducting circuit-QED (quantum electrodynamics) system is a promising candidate for quantum computing and quantum information processing, which serves also as an ideal platform for quantum measurement and quantum control studies. In this context, a large number of cavity photons may be involved in the quantum dynamics and will degrade the simulation efficiency. To avoid this difficulty, it is helpful to eliminate the degrees of freedom of the cavity photons, and obtain an effective master-equation description which contains only the qubit states. In this work, we examine two such schemes, the adiabatic elimination (AE) and the more recently proposed polaron transformation (PT) approaches, by comparing their results with exact numerical simulations. We find that in the absence of qubit-flip, which is a specific quantum nondemolition (QND) measurement, the PT scheme is superior to the AE method. Actually, in this case the PT scheme catches the measurement dynamics exactly. However, in the presence of qubit-flip such as for qubit oscillation measurement, the PT scheme is no longer better than the AE approach. We conclude that both schemes, in the weak measurement regime, can work almost equally well. This corresponds to strong cavity damping or weak coupling between the qubit and cavity photons. Out of this regime, unfortunately, one has to include the cavity photons into numerical simulations and more advanced methods/techniques are waiting for their exploration in this field.
Fractal eroded safe basins in a forced Holmes-Duffing system and its control by delayed velocity feedback
Authors: Shang Hui-Lin  ,   School of Mechanical Engineering, Shanghai Institute of Technology, Shangha 200235, China
Published: December 2020

A forced Holmes-Duffing system is considered in this paper. A delayed velocity feedback is opplied to the system. The erosion of safe basin, caused by the periodic excitation, and the effects of delayed velocity feedback on the controlling of the fractal eroded safe basin are investigated. The conditions of fractal erosion of the basin boundary are obtained by the Melnikov method. Then considering the time delay as a variable parameter, the evolutions of safe basin with time delay are presented numerically by the 4th Runge-Kutta and the point-to-point mapping method. It is found that the increase of time delay can enhance the threshold of the fractal erosion of the basin boundary under a weak and positive feedback gain so as to reduce the basin erosion. These imply that the delayed velocity feedback can control the basin erosion of the system effectively.
Frequency measurement of dual frequency He-Ne laser based on a femtosecond optical frequency comb
Authors: Wu Xue-Jian  , Wei Hao-Yun  , Zhu Min-Hao  , Zhang Ji-Tao  , Li Yan  ,   State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instruments and Mechanology, Tsinghua University, Beijing 100084, China
Published: December 2020

A frequency measurement system for dual frequency He-Ne laser is set up based on a fiber femtosecond optical frequency comb and an external cavity diode laser. Using a Rb clock as a frequency standard, the diode laser that is locked to the optical frequency comb is traced to the Rb clock, and then the frequencies of the orthogonal polarized lasers are measured by beating with the locked diode laser at the same time. Locking the diode laser to the 1894449 th comb mode, the absolute frequency of the diode laser is 473612190000.0 ± 2.7 kHz, with a relative frequency uncertainty of 5.7×10-12. A commercial dual frequency He-Ne laser is measured to test the system, and the results show that the mean absolute frequencies of the horizontal polarized laser and the vertical polarized laser are 473612229934 kHz and 473612232111 kHz, respectively, with a relative Allan deviation of 5.2×10-11 at 1024 s, and the mean split frequency is 2.177 MHz with a standard deviation of 2 kHz.
Experimental investigation on ionized ultracold molecules formed in a magneto-optical trap by time-of-flight mass spectroscopy
Authors: Yuan Jin-Peng  , Ji Zhong-Hua  , Yang Yan  , Zhang Hong-Shan  , Zhao Yan-Ting  , Ma Jie  , Wang Li-Rong  , Xiao Lian-Tuan  , Jia Suo-Tang  ,   Laser Spectroscopy Laboratory of Shanxi University, State Key Laboratory of Quantum Optics and Quantum Optics Devices, Taiyuan, Shanxi 030006, China
Published: December 2020

We use time-of-flight mass spectroscopy to detect the ultracold ground state Cs2 molecules formed directly by a photoassociation due to the trapping laser beams and repumping laser beam in a magneto-optical trap. We investigate the dependences of the Cs2+ intensity on operating voltage of micro-channel-plate, accelerating field intensity and duration time of the accelerating field. The experimental results are consistent with theoretical fitting. We obtain the best optimal parameters suited to our experimental condition, which is important for the future experiment on ultracold molecule photoassociation and photoionization spectroscopy.
Sensitivity of Delta-P1 approximation model to second-order parameter
Authors: Wang Rui  , Wang Yu-Shan  ,   Department of Physics, College of Science, Shihezi University, Shihezi 832000, China;,   College of Water Conservancy & Architectural Engineering, Shihezi University, Shihezi 832000, China
Published: December 2020

The sensitivity of the second-order parameter of the Henyey-Greenstein phase function based on the spatially-resolved diffuse reflectance within the two-point-source approximation to the Delta-P1 approximation model is studied, and the analytical expression of the sensitivity is derived. The results show that the analytic solution of the Delta-P1 approximation model for reflectance contains the second-order parameter of the scattering phase function compared with the diffusion approximation model, and the second-order parameter has significant influence (the extreme value greater than 30%) on the analytic solution for spatially-resolved diffuse reflectance with small source-detector separations ( 1.5 mm) no matter whether the absorption is weak or strong. The research has theoretical significance for obtaining the optical information abour tissue with the second-order parameter .
Supercontinuum enhancement and transfer induced by a plasma grating in air
Authors: Zhang Zong-Xin  , Xu Rong-Jie  , Song Li-Wei  , Wang Ding  , Liu Peng  , Leng Yu-Xin  ,   State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
Published: December 2020

We experimentally investigate the plasma grating created by two intersecting ultrashort laser pulses, and its effects on the supercontinuum generated from femtosecond laser filamentation. The enhanced supercontinuum generation is observed, with a plasma grating formed. And an energy transfer of the supercontinuum is demonstrated, from one pulse to the other, due to the diffraction property of plasma grating. The theoretical calculation accords well with the experimental result.
Nonlinear phase noise analysis of long-haul interferometric fiber sensing system
Authors: Chen Wei  , Meng Zhou  , Zhou Hui-Juan  , Luo Hong  ,   College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073, China
Published: December 2020

Nonlinear phase noise structure is studied in the background of long-haul interferometric fiber sensing system. The influence of each factor is analyzed and evaluated in detail, and suppression methods are discussed briefly. The results show that phase noise of the system mainly includes the phase noise converted from intensity noise, the phase noise caused by nonlinear effects induced laser linewidth variations as well as the phase noise introduced by self phase modulation and cross phase modulation. Stimulated Brillouin scattering and four-wave mixing can cause intensity noise and then it turns into phase noise. For the fiber sensing system which has a narrow detecting bandwidth, the corresponding noise induced by four-wave mixing can always be neglected. Stimulated Brillouin scattering, four-wave mixing and modulation instability can cause laser linewidth broadening, leading to the increase of phase noise. When the number of channels is large, the phase noise introduced by cross phase modulation cannot be ignored. The obtained results provide a good guidance for the practical applications of long-haul interferometric fiber sensing systems.
A new approach to dealing with bidirectional reflectance of non-homogeneous atmosphere
Authors: Zhang Feng  , Ma Lei-Ming  , Shen Zhong-Ping  , Zhang Hua  , Sun Jing  , Yang Yin  ,   Chinese Academy of Meteorological Sciences, Beijing 100081, China;,   Graduate University of Chinese Academy of Sciences, Beijing 100049, China;,   Shanghai Typhoon Institute, China Meteorological Administration, Shanghai 200030, China;,   Shanghai Climate Center, Shanghai 200030, China;,   National Climate Center, China Meteorological Administration, Beijing 100081, China;,   National Meteorological Center, China Meteorological Administration, Beijing 100081, China
Published: December 2020

In satellite remote sensing, the relationship between bidirectional reflectance and optical depth is the foundation of the retrieval of the aerosols' optical depth. According to asymptotic integral theory, a new approach to dealing with bidirectional reflectance of atmospheric without artificial stratification in the single-scattering approximation. The results show that the accuracy of analytical solution obtained by the new method is high. We formulate the analytical bidirectional reflectance with the vertical continuity of the inherent optical properties. Moreover, analytical solution is relatively easy to explain some of most import features for radiative transfer process.
Sensitivity of spatially-resolved diffuse reflectance to optical parameters in the hybrid diffusion approximation
Authors: Tian Hui-Juan  , Niu Ping-Juan  ,   School of Electrical Engineering & Automation, Tianjin Polytechnic University, Tianjin Key Laboratory of Advanced Electrical Engineering and Energy Technology, Tianjin 300387, China;,   Engineering Research Center of High Power Solid State Lighting Application System, Ministry of Education, Tianjin 300387, China
Published: December 2020

Based on a theoretical model for spatial diffusion reflection with two-point-source hybrid diffusion approximate to a semi-infinite homogeneous turbid medium, expressions of the sensitivities for the absorption coefficient μa and the reduced scattering coefficient μ's are derived, and the effect of the sensitivities of the two optical parameters μa and μ's on diffuse reflectance is studied systematically in small volumes of highly absorbing medium. The results show that the sensitivity of the absorption coefficient increases approximately linearly with the increase of source-detector separation ρ, with a slope proportional to 1.4 (μ's/μa)1/4, and also indicate an optimal probe spacing ρopt at which a variable reduced scattering coefficient has a smallest effect on the measurment of optical absorption in the turbid medium. The value of ρopt is approximately equal to 3.4 times transport mean free path. The study is of great significance for the measurment of the optical properties of biological tissues and the application of diffuse reflecance spectroscopy technology.
Layered elliptical-cylindrical acoustic cloaking design based on isotropic materials
Authors: Gao Dong-Bao  , Zeng Xin-Wu  ,   College of Optoelectric Science and Engineering, National University of Defense Technology, Changsha 410073, China
Published: December 2020

A layered co-focal elliptical-cylindrical acoustic cloak is designed based on the effective medium theory. The distribution of acoustic field is simulated using the finite element method. The cloak possesses the properties of low-reflection outside and wavefront-bending in the cloak shell. The relationship between the cloaking effect and the number of discrete layers, the direction of incident wave are also investigated. The effective working frequency band can be broadened by using more layers. As the cloak is of a line-transformed type, its properties are associated with the direction of incident wave. Only when the incident wave is parallel to the major axis of the ellipse, can the cloak have the best performance. In addition, the cloak is of a cylindrical structure as the focus of the ellipse-cylinder is small enough. This work is expected to be helpful for realizing acoustic cloaks with complex shapes.
TEM study of GaN films on vicinal sapphire (0001) substrates by MOCVD
Authors: Lin Zhi-Yu  , Zhang Jin-Cheng  , Xu Sheng-Rui  , Lü Ling  , Liu Zi-Yang  , Ma Jun-Cai  , Xue Xiao-Yong  , Xue Jun-Shuai  , Hao Yue  ,   Key Laboratory of Wide Band Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi'an 710071, China
Published: December 2020

Quality properties and internal defects of unintentionally doped GaN films grown on 0.3 vicinal sapphire (0001) substrates by MOCVD are investigated by TEM. The results show that plenty of dislocations in the GaN films prepared on vicinal sapphire substrates are annihilated in the areas with a distance of 0.8 m away from substrates, and that dislocations gather in the GaN films. Based on these phenomena, a mechanism for dislocation annihilation in the GaN film prepared on vicinal substrate is proposed, which is capable of explaining the fact that vicinal substrates are able to improve the qualities of GaN films.
The evolution of microstructure and mechanical properties of Ti/Al composite synthesized by accumulative roll-bonding
Authors: Gu Su-Yi  , Fang Hong-Mei  , Zhou Zheng-Cun  , Du Jie  ,   Department of Mechano-electronic Enineering, Suzhou Vocational University, Suzhou 215104, China;,   Zhejiang Sanxin Detection and Calibration Limited Company, Hangzhou 311106, China
Published: December 2020

Ti/Al multilayered composite, mainly composed of ultrafine equiaxed grains with a mean size of 200-300 nm is successfully synthesized by accumulative roll-bonding. The microstructure evolution and mechanical properties of the multilayered Ti/Al compound are investigated.
Effect of thermal-pressure treatment on magnetoelectric transport in Nd0.7Sr0.3MnO3 ceramics
Authors: Chen Shun-Sheng  , Yang Chang-Ping  , Kan Zhi-Lan  , Medvedeva I V  , Marchenkov S  ,   Faculty of Physics and Electronic Technology, Hubei University, Wuhan 430062, China;,   School of Mathematics and Physics, Huangshi Institute Technology, Huangshi 435003, China;,   Institute of Metal Physics, Ural Division of the Russian Academy of Sciences, Ekaterinburg 620219, Russia
Published: December 2020

The Nd0.7Sr0.3MnO3 compounds are treated at a thermal pressure (HTP) of temperature 1273 K and pressure 9 GPa. The results show that the crystal structure and space group of samples keep unchanged while the lattice and structural parameters, especially the microscopic structure change remarkably, which produces significant influence on magnetoelectric transport of the Nd0.7Sr0.3MnO3 ceramic. For electrical transport of the HTP sample, no electroresistance (ER) effect occurs when loaded current is less than 1.5 mA, however, an ER effect around 200% takes place when the loaded current goes up to more than 1.5 mA. Interestingly, the peak at -T curve disappears by replacing a platform, which can return to a peak if a magnetic field is applied again. The formation of intergranular phase and insulating behaviour of sample under thermal pressure condition are suggested to be responsible for the unique transport properties.
The phonon effect of polaron and qubit in spherical shell quantum dot
Authors: Zhao Cui-Lan  , Cong Yin-Chuan  ,   College of Physics and Electronic Information, Inner Mongolia University for Nationalities, Tongliao 028043, China
Published: December 2020

The influence of phonon on the properties of polaron and qubit in spherical shell quantum dot is studied by solving accurately the time-independent Schrödinger equation, Lee-Low-Pines unitary transformation and variation methods. The numerical results indicate that phonon effect leads to a lower energy of ground (or excited) state of polaron than electronic energy of ground (or excited) state and the increased oscillating period of a qubit, and the phonon effect becomes more obvious with outer radius increasing when inner radius is const. The numerical results also show that the phonon effect cannot influence the amplitude of probability density distribution of electrons in quantum bit, and that the probability density distribution of electrons is dependent on co-ordinate and time and its amplitude is maximal in centre spherical surface and but zero in boundary surface. The probability density of electrons at each position oscillates periodically with time.
The simulation of precipitate splitting in alloy (Ⅰ): segmentation mechanism
Authors: Liu Lei  , Chen Zheng  , Wang Yong-Xing  ,   School of Materal Science and Engineering, Northwestern Polytechnical University, Xi'an 710072, China;,   State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi'an 710072, China
Published: December 2020

The splitting of particles precipitating from solid solutions, e.g. Ni-based alloy, is studied with the phase field method. The simulation results show that in the single particle system, the nucleuses of crystal with the sizes of 80l to 90l (l= 12.18 Å) split during ageing. The splitting is the result of the interaction between elastic energy and interface energy. During the earlier stage of ageing, the sharpening along of the interface of the initial spheric shape particle will lead to the solute beneficiation at the corner but impoverishment in the center of the particle, it is the splitting incubation stage (SIS). The total interface energy (TIE) appears as being of horizontal step during SIS. The particles split at 300τ (τ=4.65 s) after the SIS and at the end of splitting the TIEs reach their maxima and the total elasic energy (TEE) reaches minimum at 1000τ. The horizontal step during SIS and the extreme points of TIE and TEE are the representative features of splitting. The TIE has SIS but no extreme point lying on TIE and TEE when the particle sizes are bigger than 90l. For the particles with sizes smaller than 80l, the TIE increases up monotonically.
First-principle calculations of elastic, electronic and thermodynamic properties of TiC under high pressure
Authors: Wang Bin  , Liu Ying  , Ye Jin-Wen  ,   School of Materials Science and Engineering, Sichuan University, Chengdu 610065, China;,   Key Laboratory of Advanced Special Material and Technology, Ministry of Education, Chengdu 610065, China
Published: December 2020

First-principle investigations of the elastic, electronic and thermodynamic properties of TiC in NaCl structure under high pressure are conducted by using the plane-wave pseudopotential method and quasi-harmonic Debye model. The obtained lattice parameters, elastic constants and moduli at p=0 GPa and T=0 K are in very good agreement with the available experimental data and other theoretical results. According to the analysis of the density of states, the Ti-C bond becomes stronger with pressure increasing. The values of bulk modulus, thermal expansion coefficient, Debye temperature, entropy, Grüneisen parameter and heat capacity (CV) at different pressures and temperatures are obtained successfully by using the quasi-harmonic Debye model. The influence of pressure on bulk modulus, thermal expansion parameter and Debye temperature is greater than that of temperature. The CV decreases with the increase of pressure under the same temperature and tends to the Dulong-Petit limit at high temperature.
The interfacial electronic structures at FePc/TiO2(110) and FePc/C60 interface
Authors: Wan Li  , Cao Liang  , Zhang Wen-Hua  , Han Yu-Yan  , Chen Tie-Xin  , Liu Ling-Yun  , Guo Pan-Pan  , Feng Jin-Yong  , Xu Fa-Qiang  ,   National Synchrotron Radiation Laboratory, College of Nuclear Science and Technology, University of Science and Technology of China, Hefei 230029, China
Published: December 2020

The electronic structures at the interfaces of iron phthalocyanine (FePc)/TiO2(110), FePc/C60 and FePc:C60 blends are studied in situ by synchrotron radiation-based ultraviolet photoelectron spectroscopy (SRUPS). It is found that the interaction between organic molecules and the surface of reduced rutile TiO2(110) is stronger than that of the stoichiometric TiO2(110) interface. The energy level alignments at the FePc/C60 interface and FePc:C60 blends are drawn based on the evolutions of the interfacial electronic structures. From the SRUPS spectra, the band bending energies are found to be 0.45 eV in the C60 layer and 0.1 eV in the FePc layer at the FePc/C60 interface. The interface dipole energy is 0.2 eV at the FePc/C60 interface. The offsets between the HOMO of FePc and LUMO of C60 are 0.85 eV at FePc/C60 and 1.04 eV at FePc:C60 blends, which indicates that the blend films can improve the efficiency of the relevant optical-electric devices.
Research of dimer diffusion and dissociation on Cu surfaces
Authors: Tang Yan-Li  , Li Rong-Wu  ,   Physics Department, Beijing Normal University, Beijing 100875, China
Published: December 2020

In this paper, we use molecular dynamics simulation to analyze the diffusion and dissociation barriers of homogeneous (Cu2) and heterogeneous dimer (Ag2, Pd2) on the surface of Cu(100), (111) surface. We explore the diffusion and dissociation process and characteristics of those dimers on Cu surface and compare their diffusion and dissociation barriers of dimer, the binding energies of the dimer and substrate, substrate surface textures, temperatures, etc. The semiempirical EAM potential is used in the simulation.
Influence of B doping on structure and properties of Ti Thin Film
Authors: Zhang Ling  , He Zhi-Bing  , Liao Guo  , Chen Jia-Jun  , Xu Hua  , Li Jun  ,   School of Physics and Electronic Information, China West Normal University, Nanchong 637002, China;,   Centre of Laser Fusion Research, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

B-doped Ti film is fabricated by direct current magnetron sputtering. The doping concentration, surface morphology, crystal structure, crystal grain diameter and stress are characterized by X-ray photoelectron spectroscopy, scanning electron microscopy and X-ray diffraction, respectively. It is found that, with the increase of B doping, the crystal grain diameter decreases monotonically and reaches a minimum of 1.3 nm at a B doping concentration of 5.50 at.%. The B-doped Ti film presents a compact columnar structure at that concentration. The stress of Ti film changes from compressive stress to tensile stress when B is doped.
Light-induced magnetoconductance effect in organic light-emitting diodes
Authors: Jiao Wei  , Lei Yan-Lian  , Zhang Qiao-Ming  , Liu Ya-Li  , Chen Lin  , You Yin-Tao  , Xiong Zu-Hong  ,   School of Physical Science and Technology, MOE Key Laboratory on Luminescence and Real-Time Analysis, Southwest University, Chongqing 400715, China;,   Surface Physics Laboratory (National Key Laboratory), Fudan University, Shanghai 200433, China
Published: December 2020

Organic light-emitting diode with a structure of ITO/CuPc/NPB/Alq3/LiF/Al is fabricated. The excitons of the device are produced by laser irradiation using two kinds of laser beams which are at 442 nm and 325 nm, and the evolutions of the excitons are controlled by a small bias (which is either positive or negative, and ensures that the device does not turn on). The photo-induced magneto-conductance (PIMC), which is the dark current of the device showing no magnetic response at a small bias, is also measured at the same time. It is found that unlike the magneto-conductance in the electrical injection case, the PIMC presents significantly different results at the positive and negative small bias. The PIMC of the device increases rapidly in a range of 0-40 mT at a small forward bias, then increases slowly with the further increase of magnetic field, and finally becomes saturated gradually. But in the case of small reverse bias, although the PIMC of the device also first increases rapidly with the increase of magnetic field (0-40 mT), but it decreases after its maximum value has been reached. By using a composite model of electron-hole pairs and the theory of hyperfine interaction, the PIMC effect at the forward bias can be explained by analyzing the effects of the applied magnetic field on the micro-processes of the light-generated carrier of the device. When the device is in the case of reverse bias, due to the fact that the relationship of the energy-band of each organic layer provides the necessary conditions for the interactions between exciton and charge, the decrease of PIMC in high magnetic-fields can be attributed to the mechanism of reaction between triplet exciton and charge.
Theoretical analysis of response characteristics for the large exponential-doping transmission-mode GaAs photocathodes
Authors: Cai Zhi-Peng  , Yang Wen-Zheng  , Tang Wei-Dong  , Hou Xun  ,   State Key Laboratory of Transient Optics and Photonics, Xi'an 710119, China;,   Key Laboratory of Ultrafast Photoelectric Diagnostics Technology, Xi'an Institute of Optics and Precision Mechanics of CAS, Xi'an 710119, China
Published: December 2020

A new-type GaAs photocathode with ultrafast time response, that is, the large exponential-doping transmission-mode GaAs photocathode, is discussed in detail. The response characteristics, including quantum yield, time and spatial resolution, are numerically simulated. The analysis results show that the transit response time of the photo-excited electrons for the GaAs photocathode is extremely shortened, because the built-in electric field in GaAs layer formed by the large exponential-doping mode is benefitcial to the photoelectron transport process of GaAs photocathodes. The response time can reach about 10 ps when the thickness of GaAs dgorption layer is around, which shows that the novel NEA cathode has a better feature of temporal response than that of traditional GaAs photocathode. In addition, the quantum yield will reach ～10%-20% in the whole special response range, and the spatial resolution is improved obviously. The analysis results indicate that with high quantum efficiency guaranteed, the large exponential-doping NEA cathode overcomes the limitation of time response of traditional GaAs NEA cathode and improves the spatial resolution, which indicates that the new NEA cathode is expected to meet the demands of high-speed device and photoelectron device, and promote the further development and applications of NEA cathodes.
Calibration of velocity map imaging system and photodissociation dynamics of 1, 4-C4H8BrCl
Authors: Liu Yu-Zhu  , Xiao Shao-Rong  , Zhang Cheng-Yi  , Zheng Gai-Ge  , Chen Yun-Yun  ,   College of Physics and Opto-electronics Engineering, Nanjing University of Information Science & Technology, Nanjing 210044, China;,   Paul Scherrer Institute, Villigen 5232, Switzerland
Published: December 2020

Depletion of atmospheric ozone layers is more and more serious. Alkyl halides dissociate under the solar UV radiation with the product of free halogen atoms, which greatly damages the ozone layer and is the main culprit for the depletion of ozone layers. In this paper, methyl iodide is chosen as a calibration system of velocity map imaging. Velocity map images of iodine atom I (2P3/2) at different focus voltages are obtained in the dissociation of methyl iodine under an UV radiation of ～266 nm by techniques of velocity map imaging and REMPI (Resonance Enhanced Multiphoton Ionization). The magnification factor N of velocity map imaging system is measured to be 1.13. Photodissociation dynamics of 1, 4-C4H8BrCl under an UV radiation of ～234 nm is investigated on this velocity map imaging system. The speed and angular distributions of the fragments Br(2P3/2) and Br* (2P1/2) atoms in the dissociation are obtained and analyzed. Experimental results suggest that the dissociation of 1, 4-C4H8BrCl to both Br(2P3/2) and Br* (2P1/2) atoms under an UV radiation of ～234 nm happens promptly along the C-Br bond via repulsive surfaces after excitation. The anisotropy coefficient values are obtained from angular distributions of imaging of the fragments Br (2P3/2) and Br* (2P1/2) atoms, by which the ratio between perpendicular transition and parallel transition for those two dissociation channels are calculated. In addition, photodissociation mechanisms of CH2BrCl, 1, 2-C2H4BrCl, 1, 3-C3H6BrCl and 1, 4-C4H8BrCl at an UV radiation of ～234 nm are compared, and the dependences of dissociation mechanisms of dihalogen alkyl compounds on size of the alkyl radical are obtained.
Novel composite right/left-handed transmission line and its application to filter design
Authors: Li Tian-Peng  , Wang Guang-Ming  , Liang Jian-Gang  , Zhang Chen-Xin  ,   Missile Institute, Engineering University, Sanyuan 713800, China
Published: December 2020

Split ring resonator arrays are difficult to achieve miniaturization because of their big sizes, while complementary split ring resonators are easy to damage the other parts of the microwave circuit because it is etched on the ground layer. In order to solve these problems, a novel double-layer dielectric composite right/left-handed transmission line structure is proposed and its equivalent relative permittivity and permeability are calculated. Then the influence of dimension parameters of this novel structure on transmission characteristics is analyzed. Finally two dual-band bandpass filters are designed and fabricaled by applying a new Minkowski fractal curve to this structure, and meanwhile the dual-band characteristic of this composite right/left transmission line is demonstrated.
A novel simple fiber nonlinearity suppression method in fiber-optic transmission systems using an all optical phase pre-emphasis
Authors: Li Yuan  , Cheng Hao-Ran  , Li Wei  , Yu Shao-Hua  , Yang Zhu  ,   Department of Computer Science, Central China Normal University, Wuhan 430079, China;,   Wuhan National Lab for Optoelectronics, College of Optoelectronics Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China;,   Wuhan Research Institute of Posts & Telecommunications, Wuhan 430074, China
Published: December 2020

In this paper we propose, simulate and experimentally verify a novel and simple optical phase pre-emphasis method, which is capable of mitigating fiber nonlinearity in dense wavelength division mult-DWDM optical translation systems. In our simple method, each transmitted wavelength is modulated by a phase modulator driven by a periodic parabolic electric driving signal. Both of the simulations and experimental results verify that the proposed method can effectively mitigate the fiber Kerr nonlinearity.
Pair coherent state evolutions through parametric frequency conversion and the realization of quantized vortex states
Authors: Zhu Kai-Cheng  , Li Shao-Xin  , Zheng Xiao-Juan  , Tang Hui-Qin  ,   School of Physical Science and Technology, Central South University, Changsha 410083, China;,   Physical Staff Room, Guangdong Medical College, Dongguan 523808, China
Published: December 2020

The pair coherent state evolution during a parametric frequency conversion is analyzed. And the wavefunction of the evolving pair coherent state in configuration space is obtained. It is found that the state may become a modified Bessel-Gaussian vortex state with topological charge index q which is a new non-Gaussian state. In coherent state representation such a modified Bessel-Gaussian vortex state is an eigenstate of sum of squared two-mode annihilation operators a2 + b2. The result obtained in this paper provides a new scheme for generating quantized vortex states in experiment with currently available technology.
The theoretical study on abnormal experimental phenomenon of the elongated rod Nd:glass pulsed laser
Authors: Wang Ying-Cai  , Yang Chun-Lan  , Wang Lei  , Jin Ye  ,   Laser Institute, Hebei Academy of Sciences, Shijiazhuang 050081, China;,   Hebei Mechaeronics Inetermediute Piloe Production Base, Shijiazhuang 050081, China
Published: December 2020

According to the principle of laser and a large number of experimental data proved and also considering the influence of the ignored spontaneous emisson, we study the abnormal phenomenon that the Nd: glass rod which was longer than the optical pump cavity is optically amplified without pumping. The theoretical result is almost the same as experimental result.
Calculations of radiation impedance of a rectangular plate with flexural vibration
Authors: Ma Huan-Pei  , He Xi-Ping  , Lan Zheng-Kang  , Abulizi·Abulaiti  ,   Shaanxi Key Laboratory of Ultrasonic, College of Physics & Information Technology, Shaanxi Normal University, Xi'an 710062, China
Published: December 2020

The radiation impedance expressions of flexural vibration rectangular plate with simply supported boundary are derived, and the numerical results are obtained by using the Gauss numerical integral method. Some conclusions can be obtained on the basis of the curves of relative radiation impedances versus frequency in the different modes and those corresponding to different aspect ratios. The lower the mode, the greater the radiation impedance in the low frequency is, so are the acoustic radiated power and the quality with vibration. For a rectangular plate of certain area and mode, the more the value of r (r = a/b, aspect ratio) approximates to 1, that is, the closer the square is, the greater the radiation resistance and the radiation reactance are. The method offers a reference for determining magnitude of the radiation impedance of the rectangular plate in other complicated boundary conditions (they may be no analytical displacement solutions). The method of calculating the radiation impedance of flexural vibration can be naturally transplanted into the case of piston vibration.
Research on the dynamics of indoor pedestrian evacuation via game
Authors: Xie Ji-Jian  , Xue Yu  ,   College of Physical Science and Technology, Guangxi University, Nanning 530004, China
Published: December 2020

In the process of indoor pedestrian evacuation, the game between pedestrians greatly influence evacuation efficiency. In this paper, we introduce the boycott strength into the updated game strategy coefficient in order to investigate the influence of boycott strength on the evacuation efficiency. The relations between the evacuation time and boycott strength for different pedestrian densities and exit widths are obtained by numerical simulations based on cellular automaton model. The results show that the vying behaviors are extremely easy to spread and the crowd will turn into a vying state when the boycott strength is small. When the pedestrian density is low and the exit is wide, we encourage the pedestrians to imitate the winners to update their game strategies via offering the information about standardizing roles about rapid evacuation. When the pedestrian density is high and the exit is narrow, the information about standardizing roles about avoiding to congestion is provided. Thus, the evacuation efficiency can be enhanced. Finally, the optimal boycott strength corresponding to the shortest evacuation time in different conditions is yielded. Our study provides a new perspective to enhance the efficiency of indoor pedestrian evacuation.
Study of periodic dispersive structures using splitfield FDTD method
Authors: Lu Si-Long  , Wu Xian-Liang  , Ren Xin-Gang  , Mei Yi-Cai  , Shen Jing  , Huang Zhi-Xiang  ,   Key Lab of Intelligent Computing & Signal Processing, Ministry of Education, Anhui University, Hefei 230039, China;,   Department of Physics and Electronic Engineering, Hefei Normal University, Hefei 230061, China
Published: December 2020

The dispersive periodic structures are simulated by the split-field finite difference time domain (FDTD) method. According to the Floquet theorem, a set of auxiliary elements are introduced into the FDTD iteration to deal with electromagnetic simulation of oblique incidence on periodic structures, by combining the periodic and absorption boundary condition. We here extend the split-field method to the study of periodic dispersive structures by combining the Z transformation method. The iterative equations of the Drude dispersive model are also provided. By Comparing analytical and other numerical results, the efficiency and wide applicability of our method are demonstrated.
A U-shape plasma antenna based on excitation of 5—20 kHz alternating current power supply
Authors: Zhao Jian-Sen  , Zhang Zhi-Tao  , Wang Jian  , Yu Zhe  ,   Insititute of Marine Engineering Dalian Maritime University, Dalian 116026, China;,   Department of Physics Dalian Maritime University, Dalian 116026, China
Published: December 2020

A U-shape plasma antenna is established by a 5—20 kHz alternating current(AC) source. The structure of the antenna is described, and part of electrical characteristics are measured. Results show that in a frequency range from 50 to 400 MHz, the noise level of 5—20 kHz AC plasma antenna is close to that of a metal antenna, but much lower than that of frequency AC plasma antenna. Besides, the antenna shows good impendance and gain bandwith characteristics.
Implosion characteristics of conical wirearray Z pinches on Qiangguang1 facility
Authors: Jiang Shu-Qing  , Ye Fan  , Yang Jian-Lun  , Xia Guang-Xin  , Zhang Fa-Qiang  , Li Zheng-Hong  , Xu Rong-Kun  , Xu Ze-Ping  , Pan Ying-Jun  ,   The Key Laboratory of Optoelectronic Tchnology and System, Ministry of Education, Chongqing University, Chongqing 400044, China;,   Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900, China
Published: December 2020

Implosion and radiation characteristics of conical wire array in different regimes of implosion are investigated at the 1 MA Qiangguang-1 facility by X-ray self-emission diagnostics. Experimental results show that the shape of precursor plasma is also conical. The initial implosion takes place near the cathode by a stronger Lorenz force, forming a triangle-like structure that produces harder X ray. The current crossing the bubble in the front of the wire array near the anode persists in persist ablating, thereby leading to a zippered stagnation. The initial implosion of a bubble near the cathode is followed by the implosion zippering upwards as the zipper implosion speed is 2.59 107 cm/s. The results shows that the conical array has a broader X-ray power pulse than cylinderical wire array due to the zippered stagnation and zippered implosion of the array. The study of implosion characteristics of specialized axis symmetric wire array Z-pinch-like conical wire array can provide a valuable test bed for understanding the regime of implosion as well as theoretical model and magneto-hydrodynamic (MHD) codes, both of which primarily develop for the modeling of cylindrical wire array Z pinches.
Experimental sduty of current distribution in wirearray Zpinch plasma
Authors: Zhou Lin  , Xue Fei-Biao  , Si Fen-Ni  , Yang Jian-Lun  , Ye Fan  , Xu Rong-Kun  , Hu Qing-Yuan  , Fu Yue-Cheng  , Jiang Shu-Qiang  , Li Lin-Bo  , Chen Jin-Chuan  , Xu Ze-Ping  ,   Institute of Nuclear Physics and Chemistry, Mianyang 621900 China
Published: December 2020

The current within imploding multiwire tungsten arrays is measured using micro magnetic probes in the Qiangguang-1 facility at a current of 1.3 MA and rise time of about 70 ns. Difference in current distribution in multiwire arrays between with and without foam cylinder on the array axis is studied. Stable and reliable results are obtained for tungsten wire array Z-pinch with a wire diameter of 4.2 μm and an annular diameter of 12 mm. The results shows that the output of magnetic probe at a radius of 3.2 mm lags about 20 ns behind the discharge current pulse. After that, the ratio of inside current to the total current increases 20% within 20 ns and keeps steady for 30-40 ns. It is found that the foam cylinder has no appreciable influence on the inside current value in the initial stage of implosioin.