bluuebunny/crossref_metadata_2025 huggingface dataset:
The investigation of laser-induced plasma shock wave propagation in liquids
Authors: Bian Bao-Min  , Chen Xiao  , Xia Ming  , Yang Ling  , Shen Zhong-Hua  ,   南京理工大学应用物理系，南京 210094
Published: December 2020

Extending the propagation formula of the attenuated laser-induced plasma shock wave front with spherical symmestry in the air to the non-absolute centric symmetry is described in this paper. According to the analysis of the measured data for the laser-induced plasma shock wave front by using photo shadowgraph, a propagation formula of a rotational ellipsoid shock wave for a point source in the laser-induced plasma in a liquid is presented in this paper.The shock wave attenuation in pure water and ethanol has been investigated by means of the acoustic method. The experimental data are in agreement with the calculated results.
X-ray absorption fine structure and x-ray diffraction studies on structures of Fe70Cu30 alloys affected by mechanical alloying
Authors: Fan Jiang-Wei  , Bian Qing  , Yin Shi-Long  , Yan Wen-Sheng  , Liu Wen-Han  , Wei Shi-Qiang  ,   (1)河海大学数理系，南京 210024; (2)中国科学技术大学国家同步辐射实验室，合肥 230029; (3)中国科学技术大学物理系，合肥 230026; (4)中国人民解放军理工大学理学院，南京 210016
Published: December 2020

The XAFS and XRD techniques were used to study the local structure changes around Fe and Cu atoms in the mechanical alloying (MA) Fe70Cu30 with the milling times. At the initial MA stage milling for 2 hours, the Cu fcc lattice in Fe70Cu30 mixture is largely distorted, and the disorder factor σ(σ=σT+σS) of Cu atoms is about 0.0190 nm. After being milled for 5 hours, part of the Cu atoms located at the grain boundaries diffuses into the bcc lattice of the α-Fe phase, which makes the average disorder factor σ around Cu atoms decrease to 0.0108 nm. When the milling time reaches 10 hours, most of the Fe atoms are in the fcc Fe-Cu phase whose disorder factor σ is about 0.0119 nm, while the local structures of Cu atoms mainly maintain fcc structure, and the σ around the Cu atoms is about 0.0110 nm. We consider that the bcc structural Fe-Cu phase might be induced into the fcc structure by Cu atoms, when the concentration of Cu atoms incorporated into the bcc Fe-Cu phase is increased to about 30%—40%. The XAFS result of the Fe70Cu30 milled for 20 hours is similar to that of the Fe70Cu30 milled for 10 hours. The final MA product is composed of two phases: Fe80Cu20-like bcc structure and Fe60Cu40-like fcc structure.
Study of In/Si stable surfaces by LEED
Authors: Li Wen-Jie  , Jiang Jin-Long  , Gai Zheng  , Zhao Ru-Guang  , Yang Wei-Sheng  ,   北京大学物理学院，人工微结构和介观物理国家重点实验室，北京 100871
Published: December 2020

With the method of LEED graphic fitting, we have made a thorough study on the stability and faceting of In/Si surfaces. As a result, three new In/Si stable surfaces with less than 0.5 ML coverage ,that is, Si(2 1 4)-In, Si(3 1 7)-In and Si(4 3 6)-In and two In/Si stable surfaces with about 1ML coverage, that is, Si(1 0 1)-In and Si(3 1 3)-In, have been found. Meanwhile, the family territories of total 4 In/Si stable surfaces with less than 0.5 ML coverage and 6 with about 1ML coverage have been roughly determined. Particulaty, the family territory of Si(1 0 3)-In is rather big, even a little bigger than that of Si(1 1 1)-In.
Electron effective mass of single-wall carbon nanotubes
Authors: Lu Di  , Yan Xiao-Hong  , Ding Jian-Wen  ,   湘潭大学材料与光电物理学院，湘潭 411105
Published: December 2020

We have studied analytically the electron effective mass of single-wall carbon nanotubes. The relation between the effective mass of electrons at the bottom of lowest-lying conduction band and the tube diameter and chirality has been discussed. It is shown that geometrical structures have very important effect on the electron effective mass of single-wall carbon nanotubes.
Effect of density on the thermoelectric properties of the filled skutterudite compound La0.75Fe3CoSb12
Authors: Yang Lei  , Zhang Lan-Ting  , Wu Jian-Sheng  ,   上海交通大学材料科学与工程学院教育部高温材料及测试开放实验室,上海 200030
Published: December 2020

The effect of density on the thermoelectric properties of the filled skutterudite compound La0.75Fe3CoSb12 was investigated. The La0.75Fe3CoSb12 showed p-type conduction. The mobility increased with an increase in density. The electrical resistivity increased and the thermal conductivity decreased with decreasing density due to the pores scattering. The Seebeck coefficient is independent of density. The portion of electrical resistivity increase is consistent with that of the thermal conductivity reduction. The value of ZT of the specimen with low density is compared to that of specimen with high density. The value of ZT does not depend on density.
Influence of the interaction between atoms on the squeezing properties of atomic lasers
Authors: Zhou Ming  , Huang Chun-Jia  ,   长沙理工大学物理与电子科学系,长沙 410077
Published: December 2020

The influence of the interaction between atoms in Bose-Einstein condensate (BEC) on the squeezing properties of atomic lasers is studied under Bogoliubov approximation. The results show that the fluctuations of two quadrature components of the atomic laser can be squeezed and the interaction between atoms in BEC is disadvantageous to the squeeze of atomic lasers.
The scintillation characteristics and point defects of PbWO4 crystal by doping with trivalent ions
Authors: Liang Ling  , Gu Mu  , Duan Yong  , Ma Xiao-Hui  , Liu Feng-Song  , Wu Xiang-Hui  , Qiu Long-Qing  , Chen Ming-Nan  , Liao Jing-Ying  , Shen Ding-Zhong  , Zhang Xin  , Gong Bo  , Xue Xuan-Ping  , Xu Wei-Xin  , Wang Jing-Cheng  ,   (1)玻耳固体物理研究所，同济大学,上海 200092; (2)上海金属功能材料重点实验室,上海 200940; (3)中国科学院上海硅酸盐研究所,上海 200050
Published: December 2020

The influence of doping with different trivalent ions (La3+，Y3+，Bi3+，Sb3+)on the properties of lead tungstate crystals (PWO) has been investigated. Transmission, emission, positron annihilation lifetime and x-ray photoelectron spectra of different trivalent ions doped and undoped PWO are reported. The scintillation characteristics of the La-doped、Y-doped、Bi-doped、Sb-doped PWO crystals are discussed by comparing with the result of undoped PWO crystal. All the trivalent ions but Bi3+ doping gave a significant improvement in luminescence property of PWO obviously. The defects in PWO crystals caused by trivalent-ion dopants have been studied by means of positron annihilation lifetime and x-ray photoelectron spectra. The results can be stated as follows: La dopant can increase the concentrations of both lead vacancy (VPb) and the low-valent oxygen; Y and Bi dopant can decrease the concentrations of both VPb and low-valent oxygen; and Sb dopant can increase the concentration of VPb but decrease the concentration of low-valent oxygen. We consider that the La ions will replace the lattice Pb2+, the Y and Bi ions will occupy the lead vacancy; and the Sb ions have two valence states (+3 and +5), which will replace the lattice Pb2+ and W6+ ions, respectively.
Oxidation-induced stacking faults in nitrogen-doped czochralski silicon investigated by transmission electron microscope
Authors: Xu Jin  , Yang De-Ren  , Chu Jia  , Ma Xiang-Yang  , Que Duan-Lin  ,   浙江大学硅材料国家重点实验室,杭州 310027
Published: December 2020

The extended-defects generated during oxidation in both of nitrogen-doped Czochralski (NCZ) silicon and common Czochralski (CZ) silicon have been investigated by Transmission Electron Microscopy(TEM). It is found that the size of the oxidation-induced stacking faults (OSFs) decreases with the increase of oxidation time in NCZ silicon, and punched-out dislocations could also be observed. While in CZ silicon, there are many polyhedral oxygen precipitates generated, and the size of OSFs increases with increasing oxidation time.
Preservation dose of helium-implanted in nanocrystal titanium films
Authors: Zheng Si-Xiao  , Luo Shun-Zhong  , Liu Zhong-Yang  , Long Xing-Gui  , Wang Pei-Lu  , Peng Shu-Ming  , Liao Xiao-Dong  , Liu Ning  ,   (1)四川大学原子核科学技术研究所、辐射物理及技术教育部重点实验室，成都 610064; (2)中国工程物理研究院核物理与化学研究所，绵阳 621900
Published: December 2020

Helium concentration profile, preservation dose and release rate from a nanocrystal titanium film implanted with helium at different energy and dose have been measured by proton Rutherford backscattering technique in a range from room temperature to 500℃. It is observed that the implanted helium may be stably preserved for a long time in the nanocrystal titanium film in the temperature environment from room temperature to below 100℃ when its concentration in up to 41%—52% of He-Ti atomic ratio, and also may be effectively preserved for a long time at room temperature if their atomic concentration ratio is up to 52%—74%. Possible mechanism of helium effectively preserved in the nanocrystal film with a large boundary volume ratio is preliminarily discussed from the energy viewpoint in this paper.
Mobility model of nonuniform channel MOS by radiation induced positive spatial charge
Authors: Li Ze-Hong  , Li Zhao-Ji  , Zhang Bo  , Fan Jian  ,   电子科技大学微电子研究所,成都 610054
Published: December 2020

In this paper we suggest a radiation mobility shift model for the nonuniform channel metal-oxide-semiconductor(MOS). The distribution of two-dimensional(2D)-electric field and 2D-interaction potential, which is caused by the interaction between the ionized impurity in the depletion layer and radiation-induced positive spatial charge, is analyzed by using image charge method. The mobility expression of n-type and p-type nonuniform channel MOS is proposed. Using 2D simulator MEDICI, we simulate the mobility shift with the radiation-induced positive spatial charge. The nonuniform channel MOS's mobility shift numerical results agree well with the analytical results. Uniform channel MOS's mobility shift value agrees with that of the experiment.
Mechanism of crack formation at hard brittle particles in steels
Authors: Zhu Liang  , Zhang Ai-Hua  ,   (1)甘肃工业大学电气工程与信息工程学院,兰州 730050; (2)甘肃工业大学甘肃省有色金属新材料省部共建国家重点实验室,兰州 730050
Published: December 2020

Hard brittle particles can have an important influence on cleavage fracture in steels, and can act as cleavage initiators. Considering the strain elastic energy and the dislocation pile-up elastic energy to be released, and surface energy to be produced, during the hard brittle particle cracking, the mechanism of crack formation at hard brittle particles in steels was studied by a thermal dynamic model. It has been demonstrated theoretically that both normal stress and dislocation pile-up at the hard brittle particles are necessary for its cracking. Furthermore, a criterion for hard particle cracking has been derived, by which the critical cracking stress for the hard brittle particle was predicted not only to depend on its size and surface energy, but also to have correlations with the grain size. Their correlations are the same as the relationship between the fracture stress determined experimentally and the grain size in the case of finer grain constituents. It can be indicated that in such a situation the hard brittle particle cracking is responsible for the ultimate cleavage fracture of the material. In the case of coarser grain constituents, the critical cracking stress for the hard brittle particle is smaller than the fracture stress determined experimentally. This indicated that propagating a particle-size crack into the surrounding ferrite matrix is the critical event for the ultimate failure of the material.
Flow equations for solving elementary excitation energy spectrum of the t-J model
Authors: Wang Hong  , Lou Ping  , Zhuang Yong-He  ,   (1)安徽大学物理系,合肥 230039; (2)中国电子科技集团公司第43研究所,合肥 230022
Published: December 2020

The t-J model is one of the most important models that is often used to study the theory of the effect of strong electron correlations and high-Tc superconductivity. In this article, the method of renormalization group is used to investigate the t-J model and the elementary excitation energy spectrum of the t-J model is obtained by using the flow equations. Using the symmetry of functions, we can solve the specific expression of the energy spectrum. The result is compared with the result of Green's function method.
Preparation of high-quality large diameter polystyrene spheres opal by self-assembly method
Authors: Zhang Qi  , Meng Qing-Bo  , Cheng Bing-Ying  , Zhang Dao-Zhong  ,   中国科学院物理研究所和凝聚态物理中心，北京 100080
Published: December 2020

By upgrading the cell's structure and other conditions in experiment,we have prepared the large diameter (1μm and 700nm)artificial opal crystals with the operation of the nitrogen pressure and gently rock,and measured the samples' band gap property.This experimental result will be useful in preparation of the photonic crystal with infrared band gap.
The change of photo-induced resistivity properties in La2/3Ca1/3MnO3 thin films
Authors: Wang Shi-Lin  , Chen Chang-Le  , Wang Yue-Long  , Jin Ke-Xin  , Wang Yong-Cang  , Ren Ren  , Song Zhou-Mo  , Yuan Xiao  ,   (1)华中科技大学，武汉 430074; (2)西北工业大学应用物理系,西安 710072; (3)西北工业大学应用物理系,西安 710072;西安交通大学理学院,西安 710049
Published: December 2020

Photo-induced resistivity change p has been studied in perovskite manganite La2/3Ca1/3MnO3 thin films with a continous wave laser and modulated laser pulses in this paper. Experimental results show that in the sample films, the maximum of photo-induced resistivity change（ΔR/R）max can reach 43.5%,which is a very exciting figure in this research field. Modulated laser pulse induced signal intensity has a highly nonlinear relation with the applied current and temperature. The maximum of photo-induced resistivity increase is a second power function of the applied current, while the temperature at which the maximum appears is proportional to the bias current. There exist an optimal bias current and a temperature for optical response in this film. These results are attributed to the optical excited eg↓ carriers and polarons.
Structure and growth pattern of Si cluster (n=11—32): a tight-binding molecular dynamics simulation
Authors: Liu Yu-Zhen  , Luo Cheng-Lin  ,   (1)南京理工大学应用物理系,南京 210094;南京师范大学物理科学与技术学院,南京 210019; (2)南京师范大学物理科学与技术学院,南京 210019
Published: December 2020

By using the tight-binding molecular dynamics (TBMD) method, the structures and energies of the medium-sized silicon clusters (Si11—Si32) have been simulated, and the radial distribution function and bond-angle distribution for different size of clusters have been described in this paper. The structural transform from prolate to near-spherical configurations has been observed at the cluster size n=27 in silicon clusters.
Study on the subband properties of AlxGa1-x N/GaN modulation-doped heterostructures
Authors: Zheng Ze-Wei  , Shen Bo  , Gui Yong-Sheng  , Qiu Zhi-Jun  , Tang Ning  , Jiang Chun-Ping  , Zhang Rong  , Shi Yi  , Zheng You-Dou  , Guo Shao-Lin  , Chu Jun-Hao  ,   (1)解放军理工大学理学院，南京 211101;南京大学物理系，南京 210093; (2)南京大学物理系，南京 210093; (3)中国科学院上海技术物理研究所红外物理国家重点实验室，上海 200083
Published: December 2020

The subbands occupation and subband transport properties in modulation-doped Al0.22Ga0.78N/GaN heterostructures are studied by means of magnetotransport measurements at low temperatures and high magnetic fields. The occupation of two subbands is observed from the Shubnikov-de Haas oscillations. It is found that the total density of the two-dimensional electron gas (2DEG) as a function of the electron sheet density in the second subband is linear. The threshold of the 2DEG density that the second subband begins to be occupied is 7.3×1012cm-2. The transport mobility of the 2DEG in the two subbands is obtained by using the mobility spectrum technique. It is found that the transport mobility in the first subband decreases significantly when the relaxation of the Al0.22Ga0.78N barrier occurs. The electron mobility in the second subband is much larger than that in the first one. The results indicate that the interface roughness scattering and the alloy disorder are the main mechanisms in determining the 2DEG mobility in AlxGa1-x N/GaN heterostructures.
A non-Noether conserved quantity, i.e. Hojman conserved quantity, for nonholonomic mechanical systems
Authors: Luo Shao-Kai  , Mei Feng-Xiang  ,   (1)北京理工大学理学院,北京 100081; (2)浙江工程学院数学力学与数学物理研究所，杭州 310018;长沙大学数学力学与数学物理研究所,长沙 410003
Published: December 2020

A non-Noether conserved quantity, i.e. Hojman conserved quantity, of the nonholonomic mechanical systems is presented. Using the special Lie symmetry under infinitesimal transformations in which the time is not variable, the determining equations, the constrained restriction equations and the additional restriction equations of the nonholonomic mechanical systems are given. The Hojman conserved quantity of the corresponding holonomic systems, the weakly Hojman conserved quantity and the strongly Hojman conserved quantity of the nonholonomic systems are obtained. An example is given to illustrate the application of the result.
Transport properties of colossal magnetoresistance of Pr2/3Sr1/3MnO3 film
Authors: Liu Wei  , Chen Jin-Ping  , Guan Wei  , Xiong Guang-Cheng  , Yan Shou-Sheng  ,   北京大学物理学院，北京 100871
Published: December 2020

Measurements of the thermopower were carried out, from room temperature down to 10K, on the colossal magnetoresistance (CMR) thin films of the Pr2/3Sr1/3MnO3(PSMO) sample, which showed a dramatic reduction in the 1/f noise spectrum reported previously. At low temperatures, the thermopower is negative and shows metallic diffusion behavior of linear temperature dependence. As the temperature goes up near 150K, the thermopower reduces dramatically to show the behavior of 1/T temperature dependence,which is consistent with the prediction of the small polaron model for the high temperature phase of CMR materials. Compared with the temperature dependence of the resistance and the property of the 1/f noise near the phase transition peak, the conclusion can be reached that the percolation-typed phase separation exists in the phase transition temperature region.
Numerical calculation of Kerr spectra for MnBi magnetic multilayered films
Authors: Lin Ying-Bin  , Lai Heng  , Huang Zhi-Gao  , Du You-Wei  ,   (1)福建师范大学物理系,激光所，福州 350007; (2)福建师范大学物理系,激光所，福州 350007;南京大学固体微结构国家重点实验室，南京 210093; (3)南京大学固体微结构国家重点实验室，南京 210093
Published: December 2020

Based on the theory of propagating electromagnetic plane waves in homogenous anisotropic media and 4×4 matrix method, the Kerr spectra for the MnBi multilayered films as a function of wavelength, incident angle and layer number are simulated. It is found that the calculated Kerr spectra as a function of wavelength are in good agreement with the experimental ones for MnBi,Mn0.53Bi0.47，Mn0.52Bi0.44Sb0.04. In addition, the Kerr spectra as a function of incident angle and layer number for the MnBi multilayered films are simulated. The calculated results indicate that the magnetic layer number and incident angle greatly affect the Kerr spectra. A maximum Kerr rotation exists at some thickness of the magnetic film as the wavelength of the incident light is normal. Also, a maximum rotation is found in the simulated Kerr rotation as a function of incident angle at a fixed thickness of magnetic layer. These simulated results is important for the design of the materials.
Transient thermally induced optical nonlinearities in Kerr media
Authors: Zhou Wen-Yuan  , Tian Jian-Guo  , Zang Wei-Ping  , Liu Zhi-Bo  , Zhang Chun-Ping  , Zhang Guang-Yin  ,   南开大学物理科学学院光子学中心，天津 300071
Published: December 2020

We report out experimental results on Z-scan characteristics of co-existence of Kerr effects and transient thermo-optical effects in Kerr media in the nanosecond regime.The transition of peak-valley pattern under a certain condition was observed.There is a basic agreement between experimental data and numerical modeling.Meanwhile, a new single peak pattern or platform pattern of Z-scan curves was observed while the transient thermally induced optical nonlinearity counterbalances with Kerr effects.The research is significant to analyze correctly Z-scan measurements using a nanosecond pulse laser.
Characterization of Mg-doped GaN
Authors: Feng Qian  , Hao Yue  , Zhang Xiao-Ju  , Liu Yu-Long  ,   (1)西安电子科技大学技术物理学院，西安 710071;西安电子科技大学微电子研究所，西安 710071; (2)西安电子科技大学微电子研究所，西安 710071; (3)中国科学院物理研究所光学开放实验室，北京 100080
Published: December 2020

The properties of GaN∶Mg films grown by MOCVD on SiC substrate were studied using SEM, Raman scattering and photoluminescence spectra. The results indicate that some Mg atoms substitute Ga to become acceptors, while most of them exist as Mg interstitials(Mgi) and aggregate at defects and dislocations to reduce the tensile stress, hence a great deal of cracks were introduced during decreasing temperature process for inhomogeneous strain distribution. On the other hand, the incorporation of Mg aggravates disorder and debases the film quality. Finally, the room temperature photoluminescence measurements show the blue band attributed to DAP-type transitions from a deep donor(MgGaVN) to a shallow acceptor(MgGa).
Influences of processing parameters on the properties of ZnO thin films prepared by sol-gel spin-coating
Authors: Song Yong-Liang  , Ji Zhen-Guo  , Liu Kun  , Wang Chao  , Xiang Yin  , Ye Zhi-Zhen  ,   浙江大学硅材料国家重点实验室，杭州 310027
Published: December 2020

Zinc oxide films were prepared on Si(111) substrates by sol-gel spin-coating technique.Structure,photoluminescence,and surface morphology of ZnO thin films processed at various temperatures and times were investigated.Results showed that ZnO thin films showed a hexagonal wurtzite structure,and the extent of c-axis orientation was dependent on the processing temperature.All the thin films emitted strong band to band UV emission without defects related visible emissions at room temperature when the processing temperature was below 550℃.When the processing temperature exceeded 550℃,a strong emission band appeared in the visible region.Results also showed that the photoluminescence spectrum was dependent not only on the processing temperature but also on the processing time.Long time(3 hours) processing resulted in the aggregation of ZnO grains in the film and a lower band to band emission in the photoluminescence spectrum.
Mechanism of optical polarization dephasing in bulk GaAs and multiple quantum wells
Authors: Deng Li  , Shou Qian  , Liu Ye-Xin  , Zhang Hai-Chao  , Lai Tian-Shu  , Lin Wei-Zhu  ,   中山大学光电子材料与技术国家重点实验室/物理系，广州 510275
Published: December 2020

The optical polarization dephasing times in bulk GaAs and GaAs/Al0.3Ga0.7As quantum wells at room temperature are measured using time-resolved degenerate-four-wave mixing (DFWM). Under the conditions of excitation pulse central wavelength of 785nm and carrier density of 1011cm-2, the dephasing times of 28 and 46 fs for bulk GaAs and multiple quantum wells, respectively, are measured. Because the carrier-carrier scattering rate in quantum wells is reduced due to the confinement of the carrier behavior，the dephasing time of the quantum wells is longer than that of bulk. The dependence of the DFWM signal on the intensity and the polarization of the incident pulses is evaluated by a theoretical model of third-order nonlinear density matrix.
A study on the in-situ growth of highly oriented ZnO whisker
Authors: Yuan Hong-Tao  , Zhang Yao  , Gu Jing-Hua  ,   北京航空航天大学材料学院,北京 100083
Published: December 2020

Highly oriented ZnO whiskers were prepared on glass substrates by metal-organic chemical vapor deposition (MOCVD) at atmospheric pressure. X-ray diffraction result reveals that ZnO whiskers grow along ［0001］ direction and the crystal structure of ZnO is of wurtzite type. Scanning electron microscopic observations show that the length and shape of the whiskers are almost uniform. The diameters range from 100 to 800nm ,and the curvature radius of the whisker tip is about 50nm or even less. The chemical reaction process during the preparation of whiskers is discussed and a simple growth model of ZnO whisker deposited by MOCVD is proposed.
Study on the cell structure in semi-insulation gallium arsenide
Authors: Xu Yue-Sheng  , Tang Lei  , Wang Hai-Yun  , Liu Cai-Chi  , Hao Jing-Chen  ,   (1)河北工业大学材料学院信息功能材料研究所,天津 300130; (2)中国信息产业部1413所，石家庄 050051
Published: December 2020

Defects constructing a netlike cell structure in the 3-inch semi-insulating gallium arsenide (SI-GaAs) single crystal were studied by methods of chemical etching, x-ray anomalous transmission topography (XRT) and transmission electron microscope (TEM). The nature and the formation mechanism of these structures were analyzed. It is assumed that the cell structures are made by the clusters of small angle grain boundary caused by the movement and interaction of high density of dislocations. and the cell wall is the typical small angle grain boundary. The phase difference among the small angle grain boundaries increases with the density of dislocations.
Formation of self-assembled stripes on the anodic aluminum oxide
Authors: Liu Hong-Wen  , Guo Hai-Ming  , Wang Ye-Liang  , Shen Cheng-Min  , Yang Hai-Tao  , Wang Yu-Tian  , Wei Long  ,   (1)中国科学院高能物理研究所核分析室，北京 100039; (2)中国科学院物理研究所纳米物理与器件实验室，北京 100080
Published: December 2020

Non-polished aluminum sheets were anodized and the coexistence of self-assembled stripes and porous arrays on the Al surface was observed. The nanostructures were investigated in details using an atomic force microscope. And the formation mechanism of the stripes was discussed and simulated using Brusselator model in this work. We demonstrated that the self-assembled patterns on the Al surface were governed by the competition of formation and dissolution of alumina film during the reaction process. Moreover, this type of ordered structure could only form in certain conditions.
Effects of non-conservative forces and nonholonomic constraints on Noether symmetries of a Lagrange system
Authors: Zhang Yi  , Mei Feng-Xiang  ,   (1)北京理工大学理学院,北京 100081; (2)苏州科技学院土木工程系,苏州 215011
Published: December 2020

The effects of non-conservative forces and nonholonomic constraints on Noether symmetries and conserved quantities of a Lagrange system are studied. When non-conservative forces or nonholonomic constraints are inserted in a Lagrange system, the Noether symmetries and the conserved quantities of the system may vary. Some Noether symmetries disappear, some new Noether symmetries emerge, and under certain conditions, some Noether symmetries will still remain. The conditions under which the Noether symmetries and the conserved quantities of the system will remain are given, and two examples are given to illustrate the application of the results.
Simulation of thermal convection in a vertical slot using the lattice Boltzmann model
Authors: Zhao Ying  , Ji Zhong-Zhen  , Feng Tao  ,   (1)中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室,北京 100029; (2)中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室,北京 100029;中国人民解放军理工大学理学院,南京 211101
Published: December 2020

A new distribution function of energy is introduced and coupled with a velocity distribution function of particle and applied to study a hot fluid field. Thus, a new lattice Boltzmann model is constructed by both energy and velocity distribution functions and Boltzmann equation in the BGK form, which satisfies the conservation criteria of mass, momentum and energy. Thermal convection in a vertical slot is calculated by using the present lattice Boltzmann model. The numerical results have shown that multi-vortexes in the flow field will take place for Prandtl number Pr=1 and Grashof number 1.3×1026. The numerical results are in good agreement with Lee's studies.
Jacobi elliptic function expansion method under a general function transform and its applications
Authors: Liu Guan-Ting  , Fan Tian-You  ,   (1)北京理工大学理学院,北京 100081; (2)北京理工大学理学院,北京 100081;内蒙古师范大学数学系,呼和浩特 010022
Published: December 2020

A Jacobi elliptic function expansion method under a general function transform, which is more general than the Jacobi elliptic function expansion method under a traveling wave transform, is proposed to construct the exact solutions of nonlinear evolution equations. It is shown that some new exact periodic solutions of them are obtained by this method and these new solutions include previous solutions. Meanwhile, it is proved that the periodic solutions of some nonlinear evolution equations must be traveling solutions.
Bound states for Dirac equation with Wood-Saxon potential
Authors: Chen Gang  ,   绍兴文理学院物理系,绍兴 312000
Published: December 2020

The s wave exact bound state solutions of Dirac equation are obtained when the Wood-Saxon -type scalar potential is not less than its vector potential.
Bound states of relativistic particles in Rosen-Morse potential
Authors: Chen Gang  ,   绍兴文理学院物理系,绍兴 312000
Published: December 2020

The exact bound state solutions of the Klein-Gordon equation and Dirac equation with scalar and vector Rosen-Morse potentials are obtained in this paper. In addition, we use the supersymmetric quantum mechanics and shape invariance to get the bound state energy spectrum and use a change of variable to obtain the wave function. The above methods are extended to relativistic quantum mechanics.
Exact solutions to the Schr?dinger equation for the anharmonic oscillator potential
Authors: Lu Fa-Lin  , Chen Chang-Yuan  ,   盐城师范学院物理系,盐城  224002
Published: December 2020

The radial wave function of Schr?dinger equation for the anharmonic oscillator potential V(r)=ar2+br4+cr6 can be written in the form of a product of an exponential function and a polynomial function .The exact energy and wave function of the potential are obtained by using the relation for the coefficient of the polynomial function. In the bound states, the results show that parameters a,b and c in the model potential have to satisfy relevant restraint conditions.
Single-photon interference and router-control in an optic fiber Sagnac interferometer
Authors: Wu Guang  , Zhou Chun-Yuan  , Zeng He-Ping  ,   华东师范大学光谱学与波谱学国家教育部重点实验室，物理系，上海 200062
Published: December 2020

A novel scheme to realize stable single-photon interference and router-control is demonstrated in this paper. Phase difference between clockwise and counter-clockwise single-photons is controlled by time-division phase modulation in an optic fiber Sagnac loop. Due to the annular geometric configuration of the Sagnac loop, clockwise and counter-clockwise single-photons travel the same optical path and have the same slowly-varying phase drifts, which are automatically compensated. Furthermore, clockwise and counter-clockwise single-photons encounter the same polarization mode dispersion, which is also automatically compensated at the exit port of the Sagnac interferometer. Long-distance single-mode optic fiber at 1550 nm is used in our experimental realization. Fringe visibility of single-photon interference higher than 98% and fidelity of single-photon router-control higher than 90% have been obtained in a Sagnac fiber loop of 5 km. We also realized a stable single-photon interference in Sagnac fiber loops as long as 27 and 52 km. The corresponding fringe visibilities were higher than 94% and 84%, respectively.
Reconstructing the Wigner function of cavity fields with the micromaser
Authors: Zhang Zhi-Ming  ,   上海交通大学物理系，上海 200240
Published: December 2020

A scheme for reconstructing the Wigner function of cavity fields is proposed, and this scheme can be realized with the micromaser. We find that there is a simple relation between the Wigner function of cavity fields and the atomic populations. Therefore, we can reconstruct the Wigner function of cavity fields by measuring the atomic populations in the micromaser experiments. We test our theory with the one-photon Fock state and the Schr?dinger cat state, and find that the results are rather good.
Phase Landau states
Authors: Tian Xu  , Zhao Zhong-Yun  , Li Jian-Qing  ,   武汉理工大学理学院,武汉 430070
Published: December 2020

Phase eigenstates for the Landau system (planar charged particle moving in a uniform magnetic field) are built. It is convenient to use these states to describe the circular motion of the charged particle. The results obtained do not depend on gauges.
A parameter-modulated method for chaotic digital communication based on state observers
Authors: Li Guo-Hui  , Xu De-Ming  , Zhou Shi-Ping  ,   (1)上海大学理学院,上海 200436; (2)上海大学通信与信息工程学院, 上海 200072; (3)上海大学通信与信息工程学院,上海 200072
Published: December 2020

By designing an appropriate state observer, we have constructed two subsystems which alternately synchronize the chaotic drive system. When the parameter of the transmitter is modulated using the binary digital signal, the two systems can alternately be synchronized with the chaotic system. In the receiver, information is demodulated by analyzing synchronization error. An observer-based parameter modulation and demodulation Henon system was chosen to be a typical example. Numerical simulation is carried out to illustrate the effectiveness and efficiency of the proposed method.
Power spectrum research of twice sampling stochastic resonance response in a bistable system
Authors: Leng Yong-Gang  , Wang Tai-Yong  , Qin Xu-Da  , Li Rui-Xin  , Guo Yan  ,   (1)天津大学机械工程学院,天津 300072; (2)天津大学机械工程学院,天津 300072;中国煤炭经济学院计算机系,烟台 264005; (3)中国煤炭经济学院计算机系,烟台 264005
Published: December 2020

The characteristics of Lorentzian distribution in the power spectrum of a stochastic resonance(SR) from a bistable system have been investigated, and then the viewpoint of producing an identifiable SR peak only at the lower frequency area where the power energy being concentrated has been proposed. With big values of parameters, the spectral properties of a twice sampling stochastic resonance(TSSR) from a bistable system is probed in detail. Take the detection of a weak signal overwhelmed in heavy noise as an example, the application of the TSSR technique is shown finally.
The principles of pressure sensors based on photonic crystal
Authors: Xu Zhen-Yu  , Zhang Ruo-Jing  , Gong Yi-Ling  ,   同济大学固体力学国家教育部重点实验室，上海 200092
Published: December 2020

The mechanism of photonic crystal pressure sensor was described in this paper, after an examination of the relationship of the pressure on a one-dimensional photonic crystal and its photonic band gap (PBG) property. The results show that there is a simple relationship between the pressure and the stop wave length. This makes it possible to know the load by studying the PBG property or to change the PBG property by loading; the loads can be mechanical loads or thermal loads. Since the structure scale is similar to the wave length, it is possible to realize a series of sensors with very high exactness.
On micro scanning forces under the coupling deformation of atomic force microscope probe
Authors: Zhang Xiang-Jun  , Meng Yong-Gang  , Wen Shi-Zhu  ,   清华大学摩擦学国家重点实验室，北京 100084
Published: December 2020

Micro cantilever probe of atomic force microscope (AFM) is a typical micro mechanical component, which is under a coupling deformation during the contact scanning process. Numerical simulations of micro scanning forces and micro topography are presented to investigate the influence of the coupling deformation of AFM probe under the AFM contact mode. It is demonstrated that the normal scan force is actually not constant, which is coupled with the lateral force on an asperity of sample surface, increasing together uphill and decreasing together downhill. The coupling relationship increases with the surface slope, tip height, etc. Coupling deformation of the probe proves to play a minor role on the AFM micro topography image and the perpendicular scan force. However, surface slope plays an important role on the variation of lateral force, and the peak positions of lateral force are not accordant with that of surface topography. These results are in good agreement with those previous AFM experiments.
Microscopic approach of the spectral property of 1+ and high-spin states in 124 Te nucleus
Authors: Shi Zhu-Yi  , Ni Shao-Yong  , Tong Hong  , Zhao Xing-Zhi  ,   贵州民族学院物理与电子科学技术系，贵阳 550025
Published: December 2020

Using a microscopic sdIBM-2+2q.p. approach, the spectra of the low-spin and partial high-spin states in 124Te nucleus are relatively successfully calculated. In particular, the 1+1, 1+2, 3+1, 3+2 and 5+1 states are successfully reproduced, the energy relationship resulting from this approach identifies that the 6+1, 8+1 and 10+1 states belong to the aligned states of the two protons. This can explain the recent experimental results that the collective structures may coexist with the single-particle states. So this approach becomes a powerful tool for successfully describing the spectra of general nuclei without clear symmetry and of isotopes located at transitional regions. Finally, the aligned-state structure and the broken-pair energy of the two-quasi-particle are discussed.
High frequency response of Salisbury screen and its related factors
Authors: Wu Rui-Xin  , Wang Xiang-Yuan  , Qian Jian  , Zhang Ming-Xue  , Zhu Hang-Fei  , Xu Pei-Hua  ,   南京大学电子科学与工程系，南京 210093
Published: December 2020

In this work, the high-frequency response of the Salisbury screen made of metallic thin film was investigated. The formulas of reflectivity and bandwidth coefficient were derived. Theoretical and numerical studies show that the spectrum of reflectivity presents a resonance type, which is symmetric to the resonance frequency. The reflectivity is determined only by the normalized surface resistance α of the metallic film at resonance, and by both α and wave impedance η2 of the isolation layer at other frequencies. For the bandwidth coefficient Δ, it is determined by the examined reflectivity Γa, η2 and α. Bandwidth coefficient can be improved by changing the wave impedance η2, and tuning the surface resistance to the optimum value αc which is correlated to Γa and not equal to the one in most cases. It is also noted that the thickness of the metallic thin film should be in the order of sub-micron or nanometers.
Entanglement and disentanglement in the nonlinear interaction between squeezing vacuum state field and atom
Authors: Huang Yan-Xia  , Zhao Peng-Yi  , Huang Xi  , Zhan Ming-Sheng  ,   (1)湖北师范学院物理系，黄石 435002;中国科学院武汉物理与数学研究所波谱与原子分子物理国家重点实验室，武汉 430071; (2)中国科学院近代物理研究所，兰州 730000; (3)中国科学院武汉物理与数学研究所波谱与原子分子物理国家重点实验室，武汉 430071
Published: December 2020

The properties of the entanglement in the intensity-dependent coupling interaction between squeezing vacuum state field and atom with an additional Kerr medium are investigated by using the von Neumann entropy. The influences of nonlinear interaction intensity of Kerr medium and the squeezing degree of initial squeezing vacuum state field on the entanglement of the quantum system are discussed. The results show that the nonlinear interaction of Kerr medium can result in the generation of the maximally entangled state, disentangled-free state or disentangled state, and the degree of entanglement is stationary.
Investigation of the high harmonic generation and ionization of atoms with long-range and short-range potentials in intense laser fields
Authors: Li Peng-Cheng  , Zhou Xiao-Xin  , Dong Chen-Zhong  , Zhao Song-Feng  ,   西北师范大学物理与电子工程学院,兰州 730070
Published: December 2020

By using numerical solutions of the time-dependent Schrdinger equation for a one-dimensional atom in intense laser fields, We investigate the high harmonic generation and ionization of the long-range and short-range potential atoms. It is found that the intensities of high harmonic generation for both cases are similar, but the short-range potential atom does not radiate the low-order harmonic spectra, and the ionization probabilities of the long-range and short-range potential atoms as functions of the laser intensity are obviously different. Our results show that the excited states of the atom play an important role in the low-order harmonic spectra and ionization probabilities.
Influence of AC-Stark shift on cavity field spectra in the non-degenerate Raman process
Authors: Gao Yun-Feng  , Feng Jian  ,   (1)聊城大学光通信研究所，聊城 252059;中国科学院武汉物理与数学研究所波谱与原子分子物理国家重点实验室，武汉 430071; (2)聊城大学教育技术系，聊城 252059
Published: December 2020

The cavity field spectrum of an atom interacting with two-mode field through non-degenerate Raman coupling with the presence of AC-Stark shift in an ideal cavity is investigated. The results for the atom in the low-level state and the initial fields in pure number states, coherent states, and squeezed vacuum states are calculated. When the initial fields are in number states, the three-peak structure of each model cavity field spectra appear for weak fields, and two-peak or single-peak structure appear for strong fields. When both field modes are in a superposition of number states initially, the cavity field spectra are generally of two-peak structure. With the increase of γ=g2/g1,one peak rises and the other peak reduces.
Lattice Boltzmann simulation for nonlinear flow in porous media with coupling reaction
Authors: Xu You-Sheng  , Li Hua-Bing  , Fang Hai-Ping  , Huang Guo-Xiang  ,   (1)华东师范大学物理系，上海 200062; (2)华东师范大学物理系，上海 200062;浙江师范大学物理系，金华 321004; (3)中国科学院上海应用物理研究所，上海 201800; (4)中国科学院上海应用物理研究所，上海 201800;桂林电子工业学院计算科学与应用物理系，桂林 541004
Published: December 2020

Based on the lattce Boltzmann method and theory of fluid flow in porous media,a numerical model is discussed for the nonlinear flow in porous media with coupling reaction.The numerical simulation results agree well with the analytical solution;and the reconstructed digital images show that there are strong coupling and anti-coupling effect between the fluid flow and the reaction,which results in the self-organization cingulum forms.All these also agree well with the experimental and theoretical prediction.
A novel FDTD simulation for plasma piecewise linear current density recursive convolution
Authors: Liu Shao-Bin  , Mo Jin-Jun  , Yuan Nai-Chang  ,   (1)国防科技大学电子科学与工程学院，长沙 410073; (2)国防科技大学电子科学与工程学院，长沙 410073;南昌大学物理系，南昌 330047
Published: December 2020

A novel finite-difference time-domain (FDTD) method, called piecewise linear current density recursive convolution method,is developed for dispersive media. The formulation of this method is derived using the convolution relationship between the current density and the electric field. The high accuracy and efficiency of this method are confirmed by computing the reflection and transmission coefficients of electromagnetic waves through a collisional plasma slab in one dimension.
The Bohm criterion for the dusty plasma sheath
Authors: Wang Zheng-Xiong  , Liu Jin-Yuan  , Zou Xiu  , Liu Yue  , Wang Xiao-Gang  ,   大连理工大学三束材料改性国家重点实验室,大连 116024
Published: December 2020

The hydrodynamic-fluid model and the self-consistent dust charging model are used to investigate the Bohm criterion for the dusty plasma sheath. The variation of the ion critical Mach number and the dust Mach number with dust density are presented, and the relation between the dust surface potential and the dust density at the sheath edge is discussed. It is shown that the ion velocity entering the sheath would exceed the ion sound velocity due to the existence of dust particles. The ion critical Mach number began declining after a maximum with the incessant increase of the dust density. The numerical results satisfy the qualitative analysis of the Sagdeev potential.
Solitons formed by ultrashort laser pulses propagating in a plasma
Authors: Zhang Qiu-Ju  , Sheng Zheng-Ming  , Zhang Jie  ,   中国科学院物理研究所光物理开放实验室,北京 100080
Published: December 2020

Using one-dimensional particle-in-cell simulations, we observed the formation of solitons which can move with high group velocities when ultrashort laser pulses at a few cycles only propagate in underdense plasma near the critical density. There exist reflection and transmission when the solitons arrive at the plasma-vacuum boundary. When the intensity of initial laser pulses increases, the velocity of the formed solitons decreases. When a laser pulse at a few tens of cycles propagates in such a plasma, a cluster of solitons are left behind, and trapped in the plasma.
Calculation of high-energy ions exploded from argon clusters in high intensity femtosecond laser pulses
Authors: Zhu Pin-Pin  , Liu Jian-Sheng  , Xu Zhi-Zhan  ,   中国科学院上海光学精密机械研究所,上海 201800
Published: December 2020

The modified nanoplasma model has been used to simulate the interaction of large Ar clusters with high intensity femtosecond laser pulses. The modified model has weakened the huge enhancement of electric field inside the clusters, thus provides a more reasonable explanation. The calculated mean kinetic energy of Ar ions is in good agreement with our previous experimental results. For further experimental work, it is the quantitative analysis of the variation of the mean kinetic energy and charge states of Ar ions exploded from the interactions with thecluster size and laser intensity.
Optimization design of a wire array load for Z-pinch plasma implosion experiments
Authors: Ding Ning  , Yang Zhen-Hua  , Ning Cheng  ,   北京应用物理与计算数学研究所,北京 100088
Published: December 2020

The Z-pinch implosion from a wire array load is one of the ways to generate strong x-ray radiation. Under the conditions of a pulsed power accelerator, the x-ray radiation yield is determined by the initial diameter chosen and mass per length of a wire array load. In this paper, the effects of the mass, the array diameter and wire diameter, as well as the array material on the implosion time, the implosion trajectory, the implosion velocity and the kinetic energy are estimated by using an infinitely thin annular shell model. The relationship among the implosion time, the implosion kinetic energy and the initial array load parameters is analyzed. The optimized parameters of a wire array load are obtained under the given conditions of a driven current. Our conclusions by using the thin shell model are in agreement with the experimental results. Hence, the thin shell model can be used to design a wire array load of Z-pinch implosion experiment.
PIC simulation of the wake field acceleration driven by triangle-shaped laser pulse
Authors: Xu Han  , Chang Wen-Wei  , Yin Yan  , Zhuo Hong-Bin  ,   国防科学技术大学理学院,长沙 410073
Published: December 2020

“Electron trapping” is the main acceleration mechanism in the laser wakefield acceleration, and the theoretical analysis indicates that more electrons are trapped when the initial velocity of the electrons are increased. A new wakefield acceleration scheme named “triangle-shaped laser pulse wakefield acceleration” is proposed and tested by 2D3V PIC simulation. The slow-rising part of the triangle-shape will excites stimulated Raman scattering(SRS) which preheats electrons while the sharp-descending part of the pulse drives the wakefield to trap more electrons. Our simulation also indicates that the side stimulated Raman scattering (SSRS) is the main instability when the length of the incident laser pulse is greater than the plasma wavelength. Furthermore, the electrostatic wave mode with the greatest growth rate in SSRS is always the one with the largest wave vector kp=(2ωp/ω0)1/2, and the scattering angle satisfies θ=cos-1(2ωp/ω0).
Generalized M2 factor of truncated beams in the cylindrical coordinate system
Authors: Luo Shi-Rong  , Lü Bai-Da  ,   (1)四川大学激光物理与化学研究所，成都 610064; (2)四川大学激光物理与化学研究所，成都 610064;激光技术国家重点实验室(华中科技大学)，武汉 430074
Published: December 2020

The propagation equations of second-order moments of truncated circularly symmetric beams are derived, which obey the propagation laws similar to those for the non-truncated case. Based on the method of generalized truncated second-order moments, the second-order characteristic parameters of two-dimensional truncated beams in the rectangular coordinate system are extended to the truncated circularly symmetric beams in the cylindrical coordinate system, and the generalized M2 factor (M2G factor) can be defined in a similar way and remains invariant upon propagation. The consistency of the theory is interpreted physically. The second-order moments parameters and M2G factor of truncated super-Gaussian beams in the cylindrical coordinate system are derived and some interesting special cases are discussed and illustrated with numerical examples.
The effect of external magnetic field, current and arc column radiuson the arc helical instability
Authors: Zou Xiu  , Gong Ye  , Liu Jin-Yuan  , Gong Ji-Quan  ,   大连理工大学三束材料改性国家重点实验室,大连 116024
Published: December 2020

The effect of external magnetic field, current and arc column radius on the helical instability is studied by using linear time perturbation theory in this paper. The arc has the effect of gas flow. The stability conditions and the growth rate of the helical instability are given.