bluuebunny/crossref_metadata_2025 huggingface dataset:
Characteristics of synchrotron radiation and the structure of the permanent magnetic wiggler
Authors: Guo Xiao-Yun  , Shi Cai-Tu  , Zhang Jiu-Chang  , Xin Hong-Bing  ,   (1)北京工商大学机械自动化学院,北京  100037; (2)北京工商大学机械自动化学院,北京  100037;中国科学院高能物理研究所,北京  100049; (3)中国科学院高能物理研究所,北京  100049
Published: December 2020

The general characteristics of the synchrotron radiation of the permanent magnetic wiggler, and the angular distribution of power and total power radiated for the permanent magnetic wiggler are introduced briefly. After briefly describing the basic structure of the permanent magnetic wiggler, we report the procedure of applying the finite element analysis to the C-shape frame and the integral structure which are the main bearer of the load,in order to determine the displacement of structure of magnet under different conditions. The displacement of the C-shape frame is calculated by the theoretical formula to provide a theoretical basis for further structure design and improvement of the permanent magnetic wiggler.
Efficiency of single photon emission in three-level system of semiconductor quantum dots with pulsed excitation
Authors: Li Yao-Yi  , Cheng Mu-Tian  , Zhou Hui-Jun  , Liu Shao-Ding  , Wang Qu-Quan  , Xue Qi-Kun  ,   (1)武汉大学物理系,武汉  430072; (2)武汉大学物理系,武汉  430072;中国科学院物理研究所表面物理国家重点实验室,北京  100080; (3)中国科学院物理研究所表面物理国家重点实验室,北京  100080
Published: December 2020

The statistic characteristics of single photon emission in single semiconductor quantum dot with pulse excitation have been investigated.With rotating-wave approximation,we deduce the dynamics equations including second-order correlation function from the master equations of the populations and discuss the correlation function of photon emission from the exciton combination under different input pulse areas.There will appear an apparant split peak around zero time delay under strong excitation.For short pulse width,the probability of single photon emission p and the efficiency of single photon emission η oscillate as the excitation intensity increases.It is revealed that high efficient single photon emissions can be realized in this system when excited with input pulse area about π and short pulse width.
Dynamical behavior of ultra-short laser pulse in a cascade three-level molecular system
Authors: Liu Ji-Cai  , Zhao Ke  , Song Yu-Zhi  , Wang Chuan-Kui  ,   山东师范大学物理与电子科学学院，济南  250014
Published: December 2020

We study the interaction between the ultra-short laser pulses and the one-dimensional symmetrical π conjugated molecular material (4,4′-bis (dimethylamino) stilbene) by solving Maxwell-Bloch equations. This kind of molecular material has strong nonlinear optical properties, and its electronic structures and dipole moments are calculated by use of density functional theory on ab initio level. The numerical results show that the slowly varying envelope approximation and the rotating wave approximation cannot accurately describe the propagation properties of the ultra-short pulse in the molecular medium. In the case of single photon resonance, the two-level model can well describe the interaction between the small area pulse and the molecular system. For large area pulse, due to the existence of strongly secondary excitation to the higher-lying levels, the three-level model should be used. When the amplitude of the incident electric field is kept constant, the third level's population increases with the increase of the pulse area.
Experimental study and numerical analysis of femtosecond pulse propagation and supercontinuum generation in highly nonlinear photonic crystal fiber
Authors: Jian Ya-Qing  , Yan Pei-Guang  , Lü Ke-Cheng  , Zhang Tie-Qun  , Zhu Xiao-Nong  ,   (1)南开大学物理科学学院，天津  300071; (2)南开大学现代光学研究所，光电信息技术科学教育部重点实验室，天津  300071
Published: December 2020

Femtosecond laser pulse propagation and supercontinuum generation in a highly nonlinear photonic crystal fiber is investigated experimentally and numerically. Consistent results of continuum generation measured and calculated for 790, 800, and 820 nm pump wavelengths are presented. It is shown that when the pump wavelength overlaps with the zero-dispersion wavelength self-phase modulation and third-order dispersion play an important role, and the oscillation structure appears in the temporal waveform of the propagating pulses, whereas in anomalous dispersion region, the formation and the red-shift of solitons are evident, and the self phase modulation plays a dominant role only in the initial stage. Further spectral broadening is due to solitons self-frequency shift, fission of higher-order solitons and four-wave mixing. It is also found that four-wave mixing occurs more easily in anomalous dispersion region than at the zero-dispersion wavelength.
Study of propagation characteristics and control of one-dimensional optical lattice soliton
Authors: Wu Jin-Hua  , Fu Xi-Quan  , Wen Shuang-Chun  ,   湖南大学计算机与通信学院，长沙  410082
Published: December 2020

Propagation of optical lattice soliton in nonlinear Kerr medium with harmonic modulation of refractive index is investigated analytically and numerically. The equations governing evolution of the soliton parameters and the conditions for soliton formation and stable propagation are obtained. It is shown that the beam is finally trapped in a guide-like channel and propagates stably when the launching angle is smaller than a critical value. The critical angle increases as the depth and period of modulation of refractive index increase, and increases as the beam width decreases. Furthermore, linear spatial chirp upsets the balance between diffraction and nonlinearity, thus affects the formation and stable propagation of the soliton, although it doesn't affect the central position of the beam. In order to maintain the soliton propagation one can offset the effect of the chirp by using proper beam power.
Optimal design of distributed Raman amplifiers employed in long-haul optical transmission systems
Authors: Tong Zhi  , Wei Huai  , Jian Shui-Sheng  ,   北京交通大学光波技术研究所，北京  100044
Published: December 2020

The optimization of pumping schemes of distributed Raman amplifiers employed in long-haul optical transmission systems is investigated in detail. Considering the received optical signal to noise ratio (OSNR) as well as nonlinear distortion and the optimal signal power distribution, i.e. uniform distribution, is achieved by using variational method. But the analytical optimal distribution does not exist when taking double Rayleigh backscattering (DRB) into account. Comparison between three Raman amplification schemes, i.e. bidirectional dual-order, first-order pumping and Raman-plus-Erbium doped fiber amplifier hybrid amplification, is carried out at identical nonlinear phase shifts. The results show that symmetric bidirectional dual-order pumping can achieve the best OSNR performance through appropriate choice of the second-order pump wavelength and second-to-first-order pump power ratio in most cases for both short- and long-span applications. However, hybrid amplification will be a better choice when the DRnoise is dominant. These results will be helpful for designing long-haul transmission systems.
Effects of target thickness on emission direction of hot electrons generated from subrelativistic intensity laser pulses interacting with foil targets
Authors: Zheng Zhi-Yuan  , Li Yu-Tong  , Yuan Xiao-Hui  , Xu Miao-Hua  , Liang Wen-Xi  , Yu Quan-Zhi  , Zhang Yi  , Wang Zhao-Hua  , Wei Zhi-Yi  , Zhang Jie  ,   (1)中国科学院物理研究所，北京  100080; (2)中国科学院物理研究所，北京  100080;中国科学院西安光学精密机械研究所瞬态光学技术国家重点实验室，西安  710068
Published: December 2020

The effects of target thickness on emission directions of hot electrons are investigated in the interaction of subrelativistic intensity laser pulses with foil targets. The results show that the emission direction of the hot electrons at the rear side of the target shifts towards the target normal direction as the target thickness increases. It can be seen that the electrostatic field at the rear side of the target surface is the main cause affecting the emission direction of the hot electrons.
Study on the annealing of Cd1－xZnxTe in In vapor
Authors: Li Wan-Wan  , Sun Kang  ,   上海交通大学复合材料研究所,上海  200030
Published: December 2020

In order to meet the requirements of the design of radiation detectors, CdZnTe (or Cd1-xZnxTe) wafers grown by vertical Bridgman method w ere annealed in the vapor of In. The nature of this treatment is a diffusion pro cess, thus it is meaningful to relate the change of resistivity to the diffusion parameters. A transformation model correlating resistivity and conduction type of CdZnTe with the main diffusion parameter —— diffusion coefficient——is put forward in this paper. Combining the model with the analysis of our experimenta l data (namely DIn = 5.17 10-9, 2.625×10-10 an d 3.455×10-11cm2·s-1), the values of the diff usion coefficient of In in Cd0.9Zn0.1Te at 1073, 973 and 873K have been given for the first time, which coincide closely with those in Cd Te given by different authors. With the data, the effect of annealing time on th e change of resistivity and conduction type for Cd0.9Zn0.1 Te slice, which is annealed in saturated In vapor at 1073, 973 and 873K, have be en simulated and good consistency acquired. This work suggests an alternative wa y to determine the diffusion coefficient in semiconductor material, and also ena bles us to analyze the diffusion process quantitatively and predict the annealin g result.
A new model for calculating the critical cooling rate of bulk metallic glass under non-isothermal condition
Authors: Wang Zhen-Yu  , Yang Yuan-Sheng  , Tong Wen-Hui  , Li Hui-Qiang  , Hu Zhuang-Qi  ,   中国科学院金属研究所，沈阳  110016
Published: December 2020

Based on the non-isothermal transformation theory and non-steady state nucleatio n theory, a new method for calculating the continuous cooling transformation cur ve and the critical cooling rate of bulk metallic glass alloys is put forward in this paper. The continuous cooling transformation curves of Zr- and Pd-based al loys are calculated and the results are in good agreement with the experimental values. It is suggested that the method can be used to evaluate glass forming ab ility of alloy systems more effectively. In addition, the calculation results sh ow that the main factors effecting the critical cooling rate are the viscosity o f melt, nucleation barrier and critical volume fraction of the crystal, the crit ical cooling rate is reduced with the increase of the viscosity, nucleation barr ier and critical volume fraction of crystal.
Study on nucleation and dynamic scaling of morphological evolution of ZnO film deposition by reactive magnetron sputtering
Authors: Liu Zhi-Wen  , Gu Jian-Feng  , Sun Cheng-Wei  , Zhang Qing-Yu  ,   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

Atomic force microscopy has been applied to study the morphological evolution o f ZnO film on Si(100) and Si(111) substrates with a native oxide layer. With dyn amic scaling of the film morphology at different growth stages, the nucleation a nd growth behavior have been studied for ZnO films deposited by radio-frequency reactive magnetron sputtering. It is found that ZnO film has three nucleation st ages, namely the stages of initial nucleation, low-rate nucleation, and seconda ry nucleation. The growth exponents of the three stages are β1=1.04 ，β2=0.25±0.01 and β3=0.74 for ZnO film on Si(100) and β1=0.51，β2=0.08±0.02 and β3=0.63 for ZnO f ilm on Si(111), respectively. In the initial nucleation stage, the intrinsic def ects on Si substrates may be responsible for the surface roughening and the dens ity of surface defects determines the nucleation density of ZnO films. The growt h behavior of ZnO film is dominated by the diffusion effect and oriented growth mechanism, as well as the coarsening mechanism induced by the lattice mismatch s tress. In the low-rate nucleation stage, few new ZnO islands are detected and t he films are roughened slowly in morphology. The deposition rate plays a role of controlling the morphological evolution and the lattice mismatch stress may be released in this stage. The secondary nucleation of ZnO films may result from th e bombardment of energetic ions or atoms on the surface of Si substrates. In the secondary nucleation stage, shadowing effect may influence the roughening of Z nO films. In the stage of steady growth, ZnO films have a roughness value much l ower than the ones in nucleation stages and grow in the form of columnar grains.
Analysis of current-density distribution and giant magnetoimpedance effect in composite wires
Authors: Liu Long-Ping  , Zhao Zhen-Jie  , Huang Can-Xing  , Wu Zhi-Ming  , Yang Xie-Long  ,   华东师范大学物理系，纳米功能材料与器件应用研究中心，上海  200062
Published: December 2020

The current-density distribution and giant magnetoimpedance (GMI) properties are theoretically described for the homogenous ferromagnetic wires and composite wi res consisting of an inner conductive core covered by an outer ferromagnetic coa ting. The numerical simulation shows that the current is distributed much close r to the surface for the Cu/FeCoNi composite wires than for FeCoNi homogenous f erromagnetic wires at the same frequency and with the same geometric size and m agnetic structure. When obvious MI effect can be observed, the skin effect has a lready been strong in its ferromagnetic coating. The skin effect is still an imp ortant factor for the GMI effect in composite wires. Above a certain frequency o f about 4MHz, the driving current will flow through the ferromagnetic coating ma inly and the electromagnetic interactions become weaker, the MI behavior in the composite wire becomes similar to that in the homogenous ferromagnetic wire.
Dielectric properties and leakage current of MgO/(Ba0.8Sr0.2)TiO3 heterostructured films prepared by sol-gel technique
Authors: Jia Jian-Feng  , Huang Kai  , Pan Qing-Tao  , Li Shi-Guo  , He De-Yan  ,   兰州大学物理科学与技术学院，兰州  730000
Published: December 2020

Ferroelectric MgO/(Ba0.8Sr0.2)TiO3 heterostruct ured films have been grown on LaNiO3/Si(100) substrates by an improve d sol-gel technique. The dielectric constant and the leakage current of (Ba 0.8Sr0.2)TiO3 films have been modified by MgO insert ion. The dramatic reduction in the leakage current has been attributed to the mi nute solid solubility of MgO in the (Ba0.8Sr0.2)TiO3 lattice and the high resistance of the MgO layers.
Coordinate transformation in the study of tape helix
Authors: Xiao Liu  , Su Xiao-Bao  , Liu Pu-Kun  ,   (1)中国科学院电子学研究所，北京  100080; (2)中国科学院电子学研究所，北京  100080；中国科学院研究生院，北京  100049
Published: December 2020

The Floquet form of electromagnetic field in travelling wave tubes with tape helix is analyzed in the cylindrical coordinates frame. The study showed that appropriate coordinate transformation is the sufficient condition for separation of variables of electromagnetic field. The separation of variables under the coordinate transformation is the basis of the theory in which the assumption about the surface current density distribution of the tape is avoided. The dispersion and coupling impedance of a typical structure are calculated. The computed and measured results agree with high accuracy.
An experimental investigation on the resonance enhanced multiphoton ionization and dissociation processes of acetone
Authors: Yao Guan-Xin  , Wang Xiao-Li  , Du Chuan-Mei  , Li Hui-Min  , Zhang Xian-Yi  , Zheng Xian-Feng  , Ji Xue-Han  , Cui Zhi-Feng  ,   安徽师范大学原子与分子物理研究所,芜湖  241000
Published: December 2020

Resonance enhanced multiphoton ionization(REMPI) dissociation channels of acetone were studied using REMPI-TOF-MS and mass-selected excitation spectra in the range of 280—286.5nm. The mass-selected excitation spectra of fragment ions were analyzed and identified. It was shown that the main dissociation channel of acetone is the photoionization of parent molecule firstly in the range of 280—286.5nm, then followed by photodissociation of the parent ion.
A mode of holistic effect in random laser
Authors: Wang Hui-Qin  , Liu Zheng-Dong  ,   南昌大学近代物理研究所，南昌  330047；南昌大学材料科学与工程学院，南昌  330047
Published: December 2020

Based on the experimentally observed phenomena of random laser, a new physical holistic effect model is studied. The random laser is due to the interaction of the local aperiodic quasi-structure with matching pump light. The random laser in ZnO powder is simulated by numerical calculation, and the results are coincident with experimental phenomena qualitatively.
Defect states in three-component phononic crystal
Authors: Li Xiao-Chun  , Yi Xiu-Ying  , Xiao Qing-Wu  , Liang Hong-Yu  ,   中南大学物理科学与技术学院，长沙  410083
Published: December 2020

Using the supercell plane wave method, we investigated the effect of the third component material as defects modifying band structure of two-dimension two-component phononic crystal (PC). It is shown that adding the third material as point defect/linear defects in the two-component PC, defect states/bands can appear in the original band gap whose position and width would have only minor changes. The frequency of the defect states/bands are affected by the third material's characteristics; and all the defect states are localized. Therefore, adding proper third material as point/linear defects to the two-component system with wide band gap where defect states/bands will fall in, some special filtered/guided states will be formed. This property has important significance in acoustic /elastic wave propagating and new acoustic applications.
An improvement of relaxation time of gas-kinetic traffic model
Authors: Zhao Jian-Yu  , Sun Xi-Ming  , Jia Lei  ,   (1)清华大学核研院，北京  100084; (2)山东大学控制科学与工程学院，济南  250061; (3)山东大学控制科学与工程学院，济南  250061；济南大学控制科学与工程学院，济南  250022
Published: December 2020

An improvement is made on relaxation time of gas-kinetic traffic model, and the density and velocity are taken into account. A test case validates that the improved gas-kinetic traffic model is more effective on suppressing the perturbation, and more stable at high vehicle densities.
The effect of axial flow on the stability in the Z-pinch
Authors: Zhang Yang  , Ding Ning  ,   北京应用物理与计算数学研究所，北京  100088
Published: December 2020

A linear analysis of the ideal magnetohydrodynamic (MHD) stability of the Z-pinch is presented in which plasma flows are included in the equilibrium. Compressibility is introduced into MHD equations via the acoustic velocity of the plasma. It is found that, compressibility can stabilize the magneto-Rayleigh-Taylor/ Kelvin-Helmholtz (MRT/KH) instability, and this allows the sheared axial flow mitigate MRT instability far more effectively. Therefore, on the early stage of the implosion, because the temperature of the plasma is not high, the compressible model is much more suitable than the incompressible one. Different flow profiles have also been investigated, and it shows that the mitigation effect of the axial flow only depends on the magnitude of the velocity shear where the perturbations concentrate.
Bremsstrahlung diagnostics of hot electrons in laser-plasma interactions
Authors: Xu Miao-Hua  , Liang Tian-Jiao  , Zhang Jie  ,   中国科学院物理研究所光物理重点实验室，北京  100080
Published: December 2020

Hot electrons produced in the ultra-intense laser-plasma interactions play very important roles in the scheme of “fast ignition”. Bremsstrahlung measurements can be an effective method to diagnose the hot electrons accelerated in the forward direction. The transport of the hot electrons and the characteristics of the bremsstrahlung photons were calculated using the Monte Carlo electron-photon transport code MCNP. The feasibility of the bremsstrahlung diagnostic method in laser plasma interactions is also discussed.
Germanium quantum dots formed by oxidation of SiGe alloys
Authors: Liu Shi-Rong  , Huang Wei-Qi  , Qin Zhao-Jian  ,   (1)贵州大学理学院光信息物理实验室，贵阳  550025；贵州教育学院物理系，贵阳  550003; (2)中国科学院地球化学研究所，贵阳  550003
Published: December 2020

We report the investigation on the oxidation behavior of Si1-xGex alloys (x=0.05, 0.15, and 0.25). In the PL spectra of Germanium quantum dots formed by the oxidation of Si1-xGex substrate, at high oxidation temperature (800℃—1000℃) an emission band from 550nm to 720nm would originate from the diameter distribution of germanium nanoparticles (Ge clusters diameter: 3nm—4nm); and at low oxidation temperature (400℃—600℃) with Laser beam radiation, there is an emission band from 650nm to 900nm which may have come from the germanium clusters (diameter: 4nm—5nm). It is clearly seen that there are several peaks at 572nm, 620nm, 671nm, 724nm, 769nm, 810nm and 861nm wavelengths along the emission band, which are correlated to the quantum confinement effect with 3.32nm, 3.54nm, 3.76nm, 3.98nm, 4.17nm, 4.35nm and 4.62nm diameters of the germanium clusters, respectively. The simulation result with MC method demonstrates that the germanium clusters of the above diameters are more stable under the above conditions. A quantum confinement model has been set up, and calculations with the UHFR method and the quantum confinement analysis have been proposed to explain the PL spectra.
Experimental study on thermopower of transition metals Fe，Co and Ni in the vicinity of Curie temperatures
Authors: Xu Shao-Yan  , Lu Bo-Qiao  , Zheng Ya-Ru  , Sun Yan  ,   辽宁师范大学物理与电子技术学院，大连  116029
Published: December 2020

Thermopower of pure metals of Fe ，Co and Ni were measured in the vicinity of Curie temperatures.The results show that the curves of thermopower against temperature behave very similarly, being concave first and convex subsequently. Consequently, three special points for each metal can be determined by the corresponding curve, namely the ferromagnetic Curie temperature Tf, Curie temperature TC, and paramagnetic Curie temperature θp. It is obvious that there is a definite transition interval of temperature between ferromagnetic state and paramagnetic state of the metal and the Curie temperature is only an intermediate value. A discussion is made which concludes that the holes in the d band contribute to the electrical conduction in the temperature interval between Tf and TC, which implies that the magnetic carriers are the holes. It is also contemplated that there may exist short range order between TC and θp.
Study of fluorinated amorphous carbon films prepared by electron cyclotron resonance chemical vapor deposition
Authors: Wu Zhen-Yu  , Yang Yin-Tang  , Wang Jia-You  ,   西安电子科技大学微电子研究所，宽禁带半导体材料与器件教育部重点实验室，西安  710071
Published: December 2020

Fluorinated amorphous carbon(a-C:F) films were deposited using C4F8 and CH4 as precursor gases by electron cyclotron resonance chemical vapor deposition (ECR-CVD). Analysis of chemical compositions and bond structures by Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) shows that the loss of CF3 and C—C termination bonds are liable for inducing reduction of film thickness after heat treatment through out-gassing process. The dielectric constant of a-C:F films increases due to increased electronic polarization and enhanced film density and the interface trap density decreases from (5—9)×1011eV-1cm-2 to (4—6)×1011eV-1cm-2 after 300℃ annealing in a nitrogen environment. The current-voltage characteristics of α-C:F films was explained by ohmic conduction at low fields and Poole-Frankel conduction at high electric fields. The trap energy of the traps at band tails formed by the delocalized π electrons decreases after annealing, leading to the increase of leakage current due to field-enhanced thermal excitation of trapped electrons into the conduction band.
The micro-photoluminescence and micro-Raman study of Zn1－xCdx Se quantum islands (dots) in CdSe/ZnSe heterostructure
Authors: Wang Fang-Zhen  , Chen Zhang-Hai  , Bai Li-Hui  , Huang Shao-Hua  , Shen Xue-Chu  ,   复旦大学物理系，应用表面物理国家重点实验室，上海  200433
Published: December 2020

We have investigated two types of Zn1-xCdxSe quantum islands in CdSe/ZnSe heterostructure with different size and Cd composition using micro-photoluminescence and micro-Raman spectroscopy. The micro-photoluminescence spectra at 4.2 K indicate that the photoluminescence peaks of the islands have a large red-shift of 166 meV when the thickness of CdSe deposition layer increased from 1.8 ML to 2.3 ML, which can't be explained by considering the change of quantum confinement potential only. We also found two other important mechanisms which may lead to the large red-shift by comparing the micro-photoluminescence and micro-Raman spectra. First, the sheet density of large Zn1-xCdxSe islands which have lower exciton ground state energy will increase and the large islands will dominant gradually the photoluminescence properties of the samples with increasing thickness of the CdSe layer. Second, the increase of Cd composition in the Zn1-xCdxSe quantum islands contributes to the large red-shift as well. This is verified by resonant Raman scattering spectra of the samples.
Detection of the recent 2000a climatic extreme anomalies based on a new kind of approach-the high-order moment method
Authors: Zhang Wen  , Gao Xin-Quan  , Dong Wen-Jie  , Li Jian-Ping  ,   (1)扬州大学物理科学与技术学院，扬州  225009;中国科学院东亚区域气候-环境重点实验室，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; (3)中国气象局气候研究开放实验室，国家气候中心，北京  100081;中国科学院东亚区域气候-环境重点实验室，北京  100029
Published: December 2020

Based on the normalized high-resolution climatic proxy data, high-order moment method is used to detect the climate extreme anomalies in recent 2000 years in this paper. Combining with filtering method to extract the dominant components at physical backgrounds from the normalized data, we analyzed the information and examined the contributions of each component of the climate extreme events. The results show that: 1) On the timescale of more than 100 years, climatic oscillation with the period of about 1000 years may exits; besides, the 20th century witnessed the most active climate extreme anomalous phenomenon in recent 2000 years, so it may correspond to an active period of climate extreme anomaly phenomenon. 2) On 20—60year timescale, climate extreme anomaly phenomenon in the period of A.D. 300—1100a is relatively distinct and that in time span of A.D.1100—1980a is comparatively mitigative. Possibly, this level makes no considerable contribution to the climatic anomaly of 20th century. This level and the century scale both reflect that for climatic change in recent 2000 years, the year around A.D. 1100a maybe the key period of climate transition. 3) On the interannual timescale (less than 20years), the years of occurrence of climatic extreme anomalies reflected in Beijing Shihua cave stalagmite proxy records has good correspondence with that of the E1 Ni?o or La Ni?a events (in this paper, only the period of 1960—1980a was considered). 4) high-order moment method has a good prospect in detecting the climatic extreme events.
Photon tunneling in a frustrated-total-internal-reflection structure composed of a single negative material
Authors: Xiang Yuan-Jiang  , Wen Shuang-Chun  , Tang Kang-Song  ,   (1)湖南大学计算机与通信学院,长沙  410082; (2)湖南大学计算机与通信学院,长沙  410082；湖南大学应用物理系,长沙  410082
Published: December 2020

The tunneling time and lateral shift of photon tunneling in a frustrated-total-internal-reflection structure composed of single negative material is derived by employing stationary-phase approximation. It is found that the tunneling time and the lateral shift are negative when the barrier is a single negative material. On account of the Hartman effect of the tunneling time and the lateral shift, the photon tunneling shows the superluminal property. An effective approach to distinguish ε-negative material and μ-negative material is proposed based on the fact that TE- and TM-polarized incident beams experience opposite lateral shift.
Dependence of optical limiting characteristics on focal length in stimulated Brillouin scattering
Authors: Gong Hua-Ping  , Lü Zhi-Wei  , Lin Dian-Yang  , Lü Yue-Lan  ,   哈尔滨工业大学光电子技术研究所,哈尔滨  150001
Published: December 2020

Adopting noise initiation mode of stimulated Brillion scattering (SBS), the influence of focal length on optical limiting power and energy is numerically simulated. It shows that the characteristic of limiting power and energy are controlled by focal length. When focal length is moderate, say 15cm, the limiting energy is lowest. When focal length is short, say 5cm, the characteristic of limiting power is close to ideal. In experiment, focusing 8ns, 1064nm, 16mJ pulses into CCl4 medium, the variation of limiting power and energy versus focal length is investigated. The experimental results are in good agreement with the conclusions predicted by the simulations.
Properties of impurity band in one-dimensional photonic crystal coupled-resonator containing defect layers with negative refractive index
Authors: Dong Hai-Xia  , Jiang Hai-Tao  , Yang Cheng-Quan  , Shi Yun-Long  ,   (1)同济大学波耳固体物理研究所，上海  200092; (2)雁北师范学院固体物理研究所,山西大同  037009; (3)雁北师范学院固体物理研究所,山西大同  037009;同济大学波耳固体物理研究所，上海  200092
Published: December 2020

The transmission through one-dimensional photonic crystal coupled-resonator containing defect layers with negative refractive index is studied by using transfer matrix method. It is found that when the refractive index of defects is changed, the coupling effect between the defect modes is varied, which results in the change of the impurity band. Some sharp transmission peaks and a wide pass band appear at the same time in the for bidden band when the refractive index of defects is appopriate. So the structure can be used as both a multiple channel narrow-band filter and a wide-band filter at the samc time.
Subgroups and supergroups of crystallographic and quasi-crystallographic point groups
Authors: Long Guang-Zhi  , Chen Ying  , Chen Jing-Zhong  ,   (1)中国地质大学材料科学与化学工程学院，武汉  430074; (2)中国地质大学地球科学学院，武汉  430074; (3)中国地质大学数学与物理学院物理系，武汉  430074;中国地质大学材料科学与化学工程学院，武汉  430074
Published: December 2020

The direct products and semidirect products of quasi-crystallographic point groups, were derived from group theory. According to crystallography theory, the stereographic projection of pentagonal system, octagonal system, decagonal system and dodecagonal system, were derived and drawn. Basing upon them, all maximal subgroups of each quasi-crystallographic point group were derived and drawn. As a result, subgroups and supergroups of the three-dimensional crystallographic and quasi-crystallographic point groups (the ‘family tree' of sixty point groups) were derived and depicted in drawing. In the ‘family tree', the minimal supergroups and maximal subgroups of sixty point groups were illustrated in detail in the form of maximal subgroup chains.
High temperature high pressure constitutive relation of materials by considering fusion enthalpy
Authors: Ran Xian-Wen  , Tang Wen-Hui  , Tan Hua  , Dai Cheng-Da  ,   (1)国防科技大学理学院技术物理研究所，长沙  410073; (2)国防科技大学理学院技术物理研究所，长沙  410073;中国工程物理研究院流体物理研究所冲击波物理与爆轰物理实验室，绵阳  621900; (3)中国工程物理研究院流体物理研究所冲击波物理与爆轰物理实验室，绵阳  621900
Published: December 2020

Basing on the modified SCG model, a high temperature and high pressure constitutive relation of materials is proposed. The change of shear modulus of aluminum with pressure as deduced from this model shows three stages: machining indurations, high temperature inteneration and melting, and turning to zero at the point of complete melting. In the first two stages, the difference in results of modified SCG model and our model is no greater than 4%, which is in the error range of dynamic experiments, and the shear modulus given by this model is in good agreement with experimental data at the point of 145GPa.
First-principles computational tensile test on an Al grain boundary
Authors: Zhang Ying  , Lü Guang-Hong  , Deng Sheng-Hua  , Wang Tian-Min  ,   北京航空航天大学理学院，北京  100083
Published: December 2020

Using a first-principles total energy method based on density functional theory within local density approximation, we have performed a first-principles computational tensile test (FPCTT) on an Al grain boundary. The theoretical tensile strength of the Al grain boundary is calculated to be 9.5 GPa at the strain of 16%. Based on the valence charge density, bond length and atomic configuration evolution with increasing strain, we demonstrate that the fracture occurs at the grain boundary interface，characterized by breaking of the grain boundary interfacial-reconstructed bonds. We further found that, because of the reduced number of the nearest neighbor of Al atoms in the grain boundary, these interfacial-reconstructed bonds have similar features to covalent bonds, which results in rather high grain boundary strength in comparison with the Al bulk.
Magnetoresistance oscillation of two-dimensional electrons gas in narrow gap dilute magnetic semiconductor
Authors: Zhu Bo  , Gui Yong-Sheng  , Zhou Wen-Zheng  , Shang Li-Yan  , Qiu Zhi-Jun  , Guo Shao-Ling  , Zhang Fu-Jia  , Chu Jun-Hao  ,   (1)兰州大学物理系,兰州  730000; (2)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; (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;兰州大学物理系,兰州  730000
Published: December 2020

This paper study the detailed magnetoresistance oscillation in Shubnikov-de Hass (SdH) of magnetic two dimensional electron gas consisting of a modulation doped n type Hg0.82Cd0.16Mn0.02Te/Hg0.3Cd0.7Te first type quantum well by changing temperature and the angle of the sample with aspect of applied magnetic field, by which found that the changing of temperature and tilt angle will cause the varying of beating node position, By analyzing beating patterns, the magnetic angle dependent Landau splitting can be separated from magnetic magnitude dependent Zeeman splitting.
Effect of magnetic field on the transmission properties of electrons in a four-terminal quantum waveguide
Authors: Gao Feng  , Wang Yan  , You Kai-Ming  , Yao Ling-Jiang  ,   (1)衡阳师范学院物理与电子信息科学系，衡阳  421008; (2)湖南大学应用物理系，长沙  410082
Published: December 2020

We investigate the quantum-mechanical transmission of electrons in a four-terminal quantum waveguide (FTQW) subjected to an inhomogeneous magnetic field perpendicular to the FTQW plane with the use of the mode-matching technique. An electron incident through one channel of the waveguide can travel into the other three channels in the quantum ballistic regime. The results show that in zero field the transmission coefficients in two channels perpendicular to the main wire are of similar behavior, but different from that of the channel parallel to the main wire. However, in an applied magnetic field, the transmission coefficients in two channels perpendicular to the main wire exhibit quite difference from each other and depend sensitively on geometric parameters. When different magnetic configurations are applied in the structure, the transmission exhibits various patterns such as step drop, wide valley, sharp peak, and so on. Our results show that one may control the transmission property of the FTQW to match practical requirements in devices by adjusting magnetic configurations or structural parameters.
Measurement of Mg content in Zn1－xMgxO films by inductively coupled plasma method
Authors: Yan Feng-Ping  , Jian Shui-Sheng  , Ogata K.  , Koike K.  , Sasa S.  , Inoue M.  , Yano M.  ,   (1)Bio Venture Center,Osaka Institute of Technology,Osaka,Japan; (2)New Material Research Center, Osaka Institute of Technology Osaka,Japan; (3)New Material Research Center, Osaka Institute of Technology Osaka,Japan;Bio Venture Center,Osaka Institute of Technology,Osaka,Japan; (4)北京交通大学光波技术研究所，北京  100044; (5)北京交通大学光波技术研究所，北京  100044;New Material Research Center, Osaka Institute of Technology Osaka,Japan
Published: December 2020

Mg contents of Zn1-xMgxO film grown on A-sapphire substrates by molecular beam epitaxy were measured by inductively coupled plasma (ICP) method. Through theoretical analysis, an expression for the difference of Mg content in Zn1-xMgxO film calculated by simple and quadratic inspection formula was given. By comparing the measured results of the ICP with electron probe microanalysis (EPMA), the consistency of ICP with simple inspection formula and EPMA was deduced when Mg content in the samples is less than 0.5, thus the correctness of the data measured by ICP was validated.
Micromagnetics study of the magnetic nano-granular films
Authors: Jiang Jian-Jun  , Yuan Lin  , Deng Lian-Wen  , He Hua-Hui  ,   华中科技大学电子科学与技术系，武汉  430074
Published: December 2020

The nano-granular magnetic films were investigated using the micromagnetics method in this paper. The nano-granular magnetic film model studied consisted of an aggregate of 122 spherical nano-granules with an fcc structure. The computational results showed that the effect of the dipolar interaction of the system on the static magnetic structure is remarkable, while the effect of exchange interaction is indistinc. The frequency dependent permeability spectra of granular films with different volume ratio of magnetic components were simulated and the percolation phenomena of nanostructural magnetic films were extensively analyzed. Thus, the percolation threshold of the system studied was obtained according to the effective medium theory. Furthermore, the design of nano-granular magnetic films with large magnetic losses were carried out.
Effects of porosity and grain sizes on the dielectric and piezoelectric properties of porous PZT ceramics and their mechanism
Authors: Zeng Tao  , Dong Xian-Lin  , Mao Chao-Liang  , Liang Rui-Hong  , Yang Hong  ,   中国科学院上海硅酸盐研究所，上海  200050
Published: December 2020

Porous lead zirconate titanate (PZT) ceramics were prepared by adding pore formers, and the effects of pore structure and grain sizes on the dielectric and piezoelectric properties of samples were investigated. The research showed that an increase in the porosity led to reduced dielectric constant as well as enhanced hydrostatic figures of merit (dh·gh). The effect of porosity on dielectric constant can be predicted by the Okazaki experiential formula and Banno model under certain conditions. An increase in grain size increases the dielectric constant, piezoelectric coefficient and hydrostatic figures of merit, which can be explained by the Okazaki space-charge theory. For the sample with 10 wt% PMMA additions sintered at 1300℃, the porosity is 34% and the longitudinal piezoelectric coefficient (d33) is very close to that of dense PZT ceramics, while the hydrostatic figures of merit (dh·gh) is about fifteen times greater than that of dense PZT ceramics. Compared with PZT-polymer composites, the dielectric constant and piezoelectric coefficient of 34% porous PZT sintered at 1300℃ is much higher and can be more efficient in resisting the interference from the ambient medium.
Resonant Raman scattering and “negative thermal quenching” of ZnO microflowers
Authors: Qin Li  , Zhang Xi-Tian  , Liang Yao  , Zhang E  , Gao Hong  , Zhang Zhi-Guo  ,   (1)哈尔滨工业大学应用物理系，哈尔滨  150001; (2)哈尔滨师范大学理化学院物理系，哈尔滨  150080; (3)哈尔滨师范大学理化学院物理系，哈尔滨  150080；哈尔滨工业大学应用物理系，哈尔滨  150001; (4)香港中文大学物理系，香港
Published: December 2020

In this paper, ZnO microflowers were synthesized on silicon substrates by the thermal oxidation of pure Zn powder(99.99%). The X-ray diffraction spectrum (XRD) showed that ZnO microflowers have a hexagonal wurtzite structure. The field-emission scanning electron microscope (FE-SEM) image indicated that as-synthesized ZnO microflowers consisted of lots of long and straight microrods, which possessed hexagonal prism morphology. The length of microrods ranges from 30 to 50μm. The resonant Raman spectrum showed multiphonon scattering process the 5th-order longitudinal optical phonon (A1(LO)) mode in the backscattering geometry, indicating that the sample is of high quality. In the temperature-dependent photoluminescence (PL) spectra, “ negative thermal quenching” phenomenon of neutral acceptor bound exciton (A0X) was observed, and its origin was discussed.
A study on percolation threshold of Ag-MgF2 nanoparticle cermet films
Authors: Cao Chun-Bin  , Cai Qi  , Jiang Xi-Shun  , Song Xue-Ping  , Sun Zhao-Qi  ,   安徽大学物理与材料学院，合肥  230039
Published: December 2020

Several methods are introduced to calculate the percolation threshold of nanoparticle cermet films made of ceramic matrix with embedded metal nanoparticles. For Ag-MgF2 nanoparticle cermet films, the percolation threshold of 0.14, which reasonably agrees with the experimental results, is calculated by using Priou's percolation threshold theory. The factors that affect cermet film percolation threshold are also discussed.
Density function theory calculation of oxygen adsorption on Au(111) surface
Authors: Zeng Zhen-Hua  , Deng Hui-Qiu  , Li Wei-Xue  , Hu Wang-Yu  ,   (1)湖南大学应用物理系，长沙  410082; (2)湖南大学应用物理系，长沙  410082；中国科学院大连化学物理研究所，大连  116023; (3)中国科学院大连化学物理研究所，大连  116023
Published: December 2020

The oxygen adsorption on Au (111) surface has been studied systematically using density function theory (DFT). The adsorption energies, adsorption structures, work functions, density of electrons and projected density of states have been calculated in wide ranges of coverage. It is found that the fcc-hollow site is the energetically favorable site for all the coverage range considered. The repulsive interaction has been identified, and the adsorption energy decreases with the coverage θ, while work function increases linearly with the coverage. It has been found that the O-Au interaction is very weak due to the fully occupied anti-bonding states from O 2p and Au 5d hybridization.
Calculation of the transmission wave of a laser pulse amplifier
Authors: Mo Jia-Qi  , Zhang Wei-Jiang  , He Ming  ,   (1)安徽师范大学,芜湖  241000；上海高校计算科学E-研究院上海交通大学研究所，上海  200240; (2)上海高校计算科学E-研究院上海交通大学研究所，上海  200240；上海交通大学数学系，上海  200240
Published: December 2020

A nonlinear transmission system for the laser pulse amplifier is discussed. Using the generalized functional-variational iteration theory and method, the corresponding approximate solution of the system is obtained, which facilitates the design of laser pulse amplifiers.
Prediction of chaotic time series based on hierarchical fuzzy-clustering
Authors: Liu Fu-Cai  , Sun Li-Ping  , Liang Xiao-Ming  ,   燕山大学电气工程学院自动化系，秦皇岛  066004
Published: December 2020

The paper introduces a new method for fuzzy modeling based on a hierarchical fuzzy-clustering scheme. The method consists of a sequence of steps aiming at developing a Takagi-Sugeno (TS) fuzzy model of optimal structure. The premise parameters' identification consists of two steps: Start from an initial fuzzy partition of input space by a nearest-neighbor clustering method to get the number of rules and the initial clustering center; then premise parameters are further processed using a fuzzy C-means algorithm (FCM). The conclusion parameters are identified by the weighted least square method and further optimized by selective recursive least square method. To illustrate the performance of the proposed method, simulations on chaotic Mackey-Glass time series prediction are performed. The results show that the chaotic Mackey-Glass time series are accurately predicted, which demonstrates the effectiveness of this method.
A confocal measurement method based on superresolution image restoration and shaped annular beam
Authors: Zhao Wei-Qian  , Chen Shan-Shan  , Feng Zheng-De  ,   哈尔滨工业大学自动化测试与控制系，哈尔滨  150001
Published: December 2020

A new confocal measurement method based on superresolution image restoration and shaped annular beam is proposed. Firstly, we employ a binary optical element (BOE) to shape a Gaussian beam into an annular beam which preliminarily improves the lateral resolution of a confocal microscopy system, then we use a superresolution image restoration technique based on the theory of maximum likelihood estimate (MLE) to retrieve the lost high frequency information of the testing image, which further enhances the lateral resolution. The experimental results indicate that a lateral resolution of better than 0.1μm is achieved when λ= 632.8nm and N.A.= 0.85. In addition to the distinct superresolution effect, the proposed method also has the advantage of low cost, therefore, it provides a novel technical way to improve the lateral resolution of a confocal microscopy system.
Measurement of the number of cold atoms trapped in cesium magneto-optical trap via probe absorption
Authors: Wang Yan-Hua  , Yang Hai-Jing  , Zhang Tian-Cai  , Wang Jun-Min  ,   量子光学与光量子器件国家重点实验室，山西大学光电研究所，太原  030006
Published: December 2020

The number of cold atoms trapped in magneto-optical trap(MOT) can be derived from probe absorption signal. After the MOT is switched off, the cold cloud freely expands in gravitational field with an initial velocity distribution. So the measurement process can be described with the interaction model between the individual stationary two-level atom and single mode resonate laser. Absorption method can largely improved the measurement precision. In this paper we introduce the physical principle of measurement and demonstrate the whole experimental procedure in detail. The number of atoms trapped in our MOT, (8±0.3)×106 is measured in experiment. And the number of steady-state atoms and the lifetime of atom trapped in MOT was used to deduce the capture rate of MOT.
Nonlinear Jaynes-Cummings model of a trapped ion and the evolution of the ion population inversion
Authors: Wang Zhong-Qing  , Duan Chang-Kui  , An Guang-Lei  ,   重庆邮电大学光电工程学院，重庆  400065
Published: December 2020

Starting from the Jaynes-Cummings (J-C) model describing the interaction of a trapped ion with a standing-wave laser field, we derive the interaction Hamiltonian on the nonlinear J-C model of the trapped ion excitated resonantly with 1-quantum vibrational mode. After solving the time-dependent states of this model, we study the evolution of population inversion for the ion numerically. It is shown that the period of the quantum collapse and revival of the population inversionis related with the Lamb-Dick parameter and the position of the ion in the standing-wave laser field. With the increasing of the parameter, it will decrease the period of the collapse and revival. When moving the ion from the node of the standing-wave laser to the antinode, the period of the collapse and revival becomes longer.
Characterization of DC argon plasma jet at atmospheric pressure
Authors: Yan Jian-Hua  , Tu Xin  , Ma Zeng-Yi  , Pan Xin-Chao  , Cen Ke-Fa  , Cheron Bruno  ,   (1)UMR6614 CNRS CORIA,Saint Etienne du Rouvray 76801,France; (2)浙江大学热能工程研究所能源清洁利用国家重点实验室,杭州  310027; (3)浙江大学热能工程研究所能源清洁利用国家重点实验室,杭州  310027；UMR6614 CNRS CORIA,Saint Etienne du Rouvray 76801,France
Published: December 2020

An original DC double anode plasma torch operating with argon at atmospheric pressure which provides a long time and highly stable plasma jet is analyzed through its electrical and optical signals. Effects of gas flow rate and current intensity on the arc dynamics behaviour are studied using standard diagnostic tools such as FFT and correlation function. An increasing current-voltage characteristic is reported for different argon flow rates. It is noted that the takeover mode is characteristic for argon plasma jet and arc fluctuations in our case are mainly induced by the undulation of torch power supply. Furthermore, the excitation temperatures and electron densities of the plasma jet inside and outside the arc chamber have been determined by means of optical emission spectroscopy (OES).The criteria for the existence of local thermodynamic equilibrium (LTE) in plasma is then discussed. The results show that argon plasma jet at atmospheric pressure under our experimental conditions is close to LTE.