bluuebunny/crossref_metadata_2025 huggingface dataset:
Distribution of electron clouds in the excited atomic state in electron-photon coincidence scattering experiment
Authors: Liu Yi-Bao  , Pang Wen-Ning  , Ding Hai-Bing  , Shang Ren-Cheng  ,   (1)清华大学物理系，北京  100084; (2)清华大学物理系，北京  100084;东华理工学院物理系，抚州  344000
Published: December 2020

Based on the general theory of the electron-photon coincidence experiment, the S tokes parameters of an excited atomic state were calculated with the distorted w ave Born approximation. According to the correlation between experiment and theo ry, the distribution of electron clouds in an excited atomic state can be descri bed by their orientation and alignment parameters. The values obtained are in g reement with the results of the experiments.
Structures and stabilities of AunXm(n+m=4，X=Cu,　Al,　Y) clusters
Authors: Wang Hong-Yan  , Li Xi-Bo  , Tang Yong-Jian  , Chen Xiao-Hong  , Wang Chao-Yang  , Zhu Zheng-He  ,   (1)四川大学原子与分子物理研究所，成都  610065; (2)四川大学原子与分子物理研究所，成都  610065;中国工程物理研究院激光聚变研究中心，绵阳  621900; (3)中国工程物理研究院激光聚变研究中心，绵阳  621900
Published: December 2020

The equilibrium geometries and electronic structure properties of mixed Aun Xm(n+m=4, X=Cu, Al, Y) have been obtained by using the B3LYP hybrid wh ich is based on non-local density functional theory method. The binding energies, ionization potential, electron affinity, the highest occupied molecular orbital ener gy level, lowest unoccupied molecular orbital energy level,and the energy gaps o f them have been calculated. By analyzing the properties of electrons using the Mulliken population method, it is concluded that impurity increases the stabilit ies of Au cluster. When Cu, Al and Y doped in Au4 cluster, the energy gaps reduce and the binding energies increase.
Investigation of bitron as a high power microwave oscillator
Authors: Li Zheng-Hong  , Meng Fan-Bao  , Chang An-Bi  , Huang Hua  , Ma Qiao-Sheng  ,   中国工程物理研究院应用电子学研究所，绵阳  621900
Published: December 2020

Bitron, as a new type of high-power microwave device, is studied in this paper. The parameters (such as microwave power and its efficiency) based on the theoretical analysis has been realized on 25D Particle in Cell (PIC) simulation code. This device is composed of two parts: a modulation cavity and an output cavity . Coupling exists between these two cavities, so the oscillation occurs under ce rtain conditions. X band bitron is designed in this paper, and its theoretical e fficiency is 294%. The process is also realized by 25 PIC simulation code, w ith an efficiency 28%, microwave frequency 942GHz, and the power output 2 25GW.
Theoretical analysis and numerical calculation of long wavelength radiation from wiggler
Authors: Li Yu-Hui  , Jia Qi-Ka  ,   中国科学技术大学国家同步辐射实验室，合肥  230029
Published: December 2020

Wiggler radiation contains not only the usual component with short wavelength radiation but also a broadband component in the long wavelength region, which emits in the near forward direction, peaked at an angle 1/γ. Firstly, spontaneous radiation from a wiggler is analyzed based on the basic formula of electrody namics. With the long wavelength approximation, a formula for the long wavelengt h is obtained. The theoretical result is well coincided with the result of numer ical calculation. Also the character of this radiation is analyzed. Secondly, th e photon fluxes coming separately from the wiggler and a bending magnet are comp ared, for the wavelength longer than 1μm. The result shows the superiority of w iggler radiation in the infrared region. Finally, the long wavelength radiation from the wiggler is compared with the undulator transition radiation and the ben ding magnetic edge emission. The result shows that long wavelength radiation fro m the wiggler is the strongest one.
Velocity-selective coherent population trapping of a nondegenerate Λ three-level atom
Authors: Xie Min  , Ling Lin  , Yang Guo-Jian  ,   北京师范大学物理系，北京  100875
Published: December 2020

We present in this paper a detailed discussion of the velocity_selective coherent population trapping of an atomic system in a nondegenerate Λ three_level configuration.Compared with the case of degenerate ground states and laser_atom resonance,the most probable value of the atomic_momentum distribution greatly decreases and much longer trapping time is needed in order to generate the same trapping effect.
A stable long-distance quantum key distribution system
Authors: Wu Guang  , Zhou Chun-Yuan  , Chen Xiu-Liang  , Han Xiao-Hong  , Zeng He-Ping  ,   华东师范大学物理系，光谱学与波谱学教育部重点实验室，上海  200062
Published: December 2020

A stable long-distance quantum key distribution system which has been just completed in our laboratory is demonstrated in this paper. The idea of “plug and pl ay" was adopted to automatically compensate the polarization mode dispersion and phase shift. A symmetrical capacitance-balance technique and magic-T network were used in the single-photon detection module, wherein a detection efficiency of more than 5% and a dark count probability of lower than 29×10-6/p ulse were achieved. As a result, we have realized stable (longer than 12 h) quantum k ey distribution experiment in 506 km single mode fiber with mean photon number of 007 and quantum bit error rate of 4%.
Absorption and dispersion in probe laser in the four-level Y-type atom system
Authors: Zhang Li-Ying  , Liu Zheng-Dong  ,   南昌大学近代物理研究所,南昌  330047
Published: December 2020

In this paper we have calculated the absorption and dispersion of the probe laser in the four_level Y_type atom system at low light levels and found that if the external light fields are changed,the system would exhibit an electromagnetically induced transparency effect.At the same time,we found that the system could also exhibit enhancement accompanied with a big negative refractive index,and if the light field phase is changed,the absorption and dispersion of the probe laser are also changed.
Idler second harmonic generation in femtosecond BBO optical parametric amplification
Authors: Ma Jing  , Zhang Ruo-Bing  , Liu Bo  , Zhu Chen  , Chai Lu  , Zhang Wei-Li  , Zhang Zhi-Gang  , Wang Qing-Yue  ,   天津大学精密仪器与光电子工程学院，光电信息技术科学教育部重点实验室，天津  300072
Published: December 2020

For femtosecond optical parametric amplification (OPA) pumped with a 400nm blue laser, limited by phase-matched condition and nonlinear crystal transparent range, the tuning range of the output parametric laser is restricted, and the blue and the near UV lasers with wavelength less than 460nm are difficult to obtain. In our experiment, we adopted the second harmonic of a Ti:sapphire nine-pass chirp pulse amplifier at 1kHz repetition rate as the pump beam, and the white- light supercontinuum as the seed beam; thus, by a type-Ⅰ noncollinear phase-mat ched broad bandwidth β-BaB2O4 (BBO) OPA, with certain exp erimental paramete rs, the amplified signal beam from 530nm to 810nm and the idler beam from 81 0nm to 17μm were obtained; at the same time, the idler second harmonic fr om 410nm to 700nm was obtained also. The idler second harmonic was cascaded with the idler beam, its pulse energy was 26μJ and the conversion efficienc y was greater than 5%. Therefore, femtosecond pulses tuned continuously from 410 nm to 810nm can be obtained by the BBO OPA with a single crystal only, there by a useful source is provided for more investigations and applications. In this paper, we also have theoretically analyzed the generation condition of the idle r second harmonic for femtosecond OPA.
Three-photon absorption properties of two novel fluorene-based derivatives
Authors: Ma Wen-Bo  , Wu Yi-Qun  , Han Jun-He  , Gu Dong-Hong  , Gan  Fu-Xi  ,   (1)河南大学物理系，开封  475001; (2)中国科学院上海光学精密机械研究所，上海  201800; (3)中国科学院上海光学精密机械研究所，上海  201800;黑龙江大学功能材料实验室，哈尔滨  150080
Published: December 2020

Two novel fluorene_based derivatives 9_(7_(9H_carbazol_9_yl)_9, 9_bis (2_ethylhexyl)_9H_fluorene_2_yl)_9H_carbazole (abbreviated as DCZF) and 2, 7_bis (4_metho xystyryl)_9, 9_bis (2_ethylhexyl)_9H_fluorene (abbreviated as BMOSF) were synthe sized and their linear absorption and one_photon fluorescence spectra were measu red. We used a 38ps, 1064nm Nd:YAG pulsed laser operating at 10 Hz to invest igate the three_photon absorption (3PA) properties of the two compounds. The re sults show that the linear absorption band of the two compounds is from 270—420 nm with absorption peaks at 330 and 380nm. The fluorescence bands were locat ed in the blue_violet region with the peak wavelengths of 369 and 442 nm, and s mall Stokes shifts were observed. Nonlinear absorption coefficients γ deriv ed from 3PA fitting curves are 678 and 592×10-20 cm3/ W2, respectively. Large optical power limiting induced by 3PA has also been demonstr ated for both dyes. When the incident irradiances reach 8 and 6 GW/cm2, t he limiting nonlinear transmissions of DCZF and BMOSF can reach to 30% and 45%, respectively.
Uniplanar compact photonic band-gap on uniaxial anisotropic substrate
Authors: Lin Bao-Qin  , Xu Li-Jun  , Yuan Nai-Chang  ,   国防科学技术大学电子科学与工程学院，长沙  410073
Published: December 2020

The uniplanar compact photonic_bandgap (UC_PBG) is a periodic planar layered str ucture which is constructed in the microstrip structures. In this paper, the sub strate is regarded as an uniaxial anisotropic medium, and the UC_PBG is analyzed using the method of lines (MoL). The process of MoL is described in detail, som e UC_PBGs with different dielectric parameters are computed. It is shown that th e complete band gaps or even larger ones appear in dispersion diagram of those UC_PBGs.
Wavelet transform analysis for phase reconstruction of spectral shearing interferometry of ultrashort optical pulses
Authors: Deng Yu-Qiang  , Wu Zu-Bin  , Chen Sheng-Hua  , Chai Lu  , Wang Qing-Yue  , Zhang Zhi-Gang  ,   (1)天津大学精密仪器与光电子工程学院，光电信息技术科学教育部重点实验室，天津   300072; (2)天津大学精密仪器与光电子工程学院，光电信息技术科学教育部重点实验室，天津   300072;北京大学信息科学与技术学院量子电子学研究所，北京  100871
Published: December 2020

We introduce the wavelet transform for phase reconstruction of SPIDER in this pa per. With the technique, we can directly read the phase from the wavelet transfo rm of spectral interferogram, which essentially eliminates the phase noise resul ting from improper temporal filters in the conventional Fourier method. The simu lation and the practical example proved the validity and reliability of this tec hnique. This technique will find more applications in generation and characteriz ation of monocycle optical pulses.
Relationship between lattice parameters and compositions of molecular beam epitaxial Hg1－xCdxTe films
Authors: Wang Qing-Xue  , Yang Jian-Rong  , Sun Tao  , Wei Yan-Feng  , Fang Wei-Zheng  , He Li  ,   中国科学院上海技术物理研究所,上海  200083
Published: December 2020

High_resolution x_ray diffraction technology is applied to the measurement of la ttice parameters and the study of strain for Hg1-xCdxTe fi lms gr own by molecular beam epitaxy. The results show that there exist both perpendicu lar strain and shear strain in Hg1-xCdxTe films. Based on crystal elastic theory, strain states in Hg1-xCdxTe films are analyz ed and calculated, and the lattice parameters of 1-xCdxTe film s at the relaxation state are obtained. It is found that the relationship betwee n lattice parameters and compositions of Hg1-xCdxTe films agrees with Vegard's law, rather than Higgins formula proposed in earlier research. It is also found that the lattice parameters can be derived from the measured data of (224) plane spacing, and that the compositions of Hg1-xCdxTe films can also be evaluated by using Vegard's law with an error about 0 01.
A phase-field simulation on the influence of thermal fluctuation on secondary branch growth in undercooled melt
Authors: Yang Hong  , Zhang Qing-Guang  , Chen Min  ,   清华大学工程力学系,北京  100084
Published: December 2020

The dendritic growth in an undercooled melt of pure substance is simulated by a phase_field model. The relationship between the dendritic growth and the parameters used in phase_field method (including undercooling, anisotropic coefficient, magnitude of thermal fluctuation) has been studied quantitatively. By employing the thermal fluctuations the birth of secondary branches has been successfully simulated. The spacing and amplitude of the secondary branches are obtained, which are in reasonable agreement with those by using the Wentzel_Kramers_Brillouin approach. Simulations indicate that the undercooling and the anisotropic coefficient have remarkable influence on the growth of the secondary branches, in which secondary branch spacing decreases with the increase of undercooling, but increases with the increase of anisotropic coefficient. The amplitude of the secondary branch decreases with the increase of anisotropic coefficient. Thermal fluctuations show strong influence on the amplitude of the secondary branch, however show less influence on the secondary branch spacing.
Electronic transport properties and simulation of random resistor network in granular mixture system of La0.7Ca0.3MnO3 and CeO 2
Authors: Wang Shi-Qi  , Lian Gui-Jun  , Xiong Guang-Cheng  ,   北京大学物理系，北京  100871
Published: December 2020

Granular mixture samples were prepared with La0.7Ca0.3MnO 3(synthesized by solid reaction) and CeO2 mixed, pressed and sintered under different conditions. In resistivity versus temperature R(T) measurements, a metal-insulator transition was observed. R(T) data demonstrated that the sintering condition had a strong influence on the properties of the samples. A low sintering temperature had influence on the growth of small granules and their boundaries,a high-temperature and long-time sintering resulted in the formation of large granules. A random resistor network (RRN) model with a new iterative average method was used to simulate the transport property of the mixture samples. The simulation and experimental result in agreement. The result indicates that the RRN model is reasonable for understanding the electronic transport of the granular mixture samples consisting of La0.7Ca0.3MnO3 an d CeO2
Effect of oxygen content on carrier localization and ion-cluster effect for the Fe-doped YBCO system
Authors: Li Ling-Wei  , Cao Shi-Xun  , Li Wen-Feng  , Liu Fen  , Chi Chang-Yun  , Jing Chao  , Zhang  Jin-Cang  ,   上海大学物理系，上海  200444
Published: December 2020

The oxygen content, Hall coefficient and superconductivity are systematically studied on YBa2Cu3-xFexOy(x=00, 01 , 02) and YBa2Cu2.8Fe0.2Oy(y=705—653) systems. The results show that ox ygen content has a great influence on the transport and transfer of carriers and the superconductivity of the samples, the suppression of Tc caused b y Cu( 1) site substitution could be weakened by the increase of oxygen content to some extent. The carrier (holes) density in CuO2 plane plays a key role i n affecti ng the superconductivity. Based on the charge transfer model, and considering th e carrier localization and ion-cluster effect resulting from Fe substitution on Cu(1) site, we have discussed the change of carrier density caused by the oxygen content and Fe doping concentration. It proves that with the increase of Fe dop ing concentration or the decrease of oxygen content (for the same doping concent ration), the efficient oxygen vacancy increases, which enhances the ion-cluster effect and the carrier localization effect, resulting in the decrease of carrier density that participats in superconducting transport in the CuO2 pl ane, and accordingly, the decrease of Tc.
Influence of magnetic field on thermal conductivity of La2－xSrxCuO4 single crystals
Authors: Zhao Jun  , Shen Cai-Xia  , Zhou Fang  , Xiong Ji-Wu  ,   中国科学院物理研究所超导国家重点实验室，北京  100080
Published: December 2020

We have measured the temperature dependence of thermal conductivity in the ab_plane as well as c_axis of a series of underdoped La2-xSrxCuO4 (x=0063, 0070, 0090, 0110, 0125) single crystals unde r ze ro and 14 T magnetic field. It is found that the thermal conductivity in both ab plane and c-axis are suppressed by the application of the magnetic fiel d parallel to the c-axis. Ｔhe temperature dependence of the thermal conduct ivity suppression is quite similar to the previously reported behavior of the an tiferromagnetic order induced by an applied magnetic field. We think that the fi eld_induced thermal conductivity suppression in ab plane is due to the elect ronic contribution, while along c-axis it is due to the phonon contribution. Both the suppressions of the thermal conductivity in ab　plane and along c-axis probably originate from the field-enhanced charge and spin ordering.
Effect of the second-order magnetocrystalline anisotropic constant on the magnetization reversal in R2Fe14B magnets
Authors: Chen Xian-Feng  ,   江苏工业学院信息科学系，常州  213016
Published: December 2020

In this work, the dependence of the second-order magnetocrystalline anisotropic constant K2 on the minimum nucleation field Hminn has been investigated by the numerical method and the analytical formulation under the second-order approximation. It is found that the contribution of K2 t o H minn is very large at low temperatures for isotropic Pr2Fe14B magnets. Although the value of Hminn for Nd2Fe14B can b e obt ained using the analytical formulation under the first-order approximation, the value of Hminn for Pr2Fe14B is achie ved using the formulation under the second-order approxiamtion. Using the obtained value of Hminn, a good linear relation between coercivity and Hminn is found in the temperature range from 20 K to room temperature.
Magnetic properties of amorphous Fe89.7P10.3 alloy nanowire arrays
Authors: Shi Hui-Gang  , Fu Jun-Li  , Xue De-Sheng  ,   兰州大学磁学与磁性材料教育部重点实验室，兰州  730000
Published: December 2020

Amorphous Fe89.7P10.3 alloy nanowire arrays were fabri cated in an anodic aluminum oxide template by means of electrodeposition. X-ray diffract ion, transmission electron microscopy, vibrating sample magnetometer and Mssbauer spectrometer are employed to study the structure and magnetic properties of the nanowire arrays. The results show that the nanowire arrays are amorphous with a perpendicular magnetic anisotropy and high coercivity Hc=304 ×104 A/m. The mean hyperfine field and the mean isomer shift of the insi de of nanowires are 215×106 A/m and 007 mm/s, respectively. The mean hype rfine field (233×106 A/m) at the end of nanowires is higher than that of th e inside of nanowires, but the mean isomer shift (004 mm/s) at the end of nanowires is smaller than that of the inside of nanowires. The average angle between the Fe magentic moment and the wire axis is 16° in the the inside of nanowires, but the average angle is 28° at the end of nanowires. Due to the shape anisotropy of nanowires, the ordered alignment of magnetic moments is realized in the disordered amorphous alloy system.
Conduction mechanism of ultra-thin gate oxide n-MOSFET after soft breakdown
Authors: Wang Yan-Gang  , Xu Ming-Zhen  , Tan Chang-Hua  , Duan Xiao-Rong  ,   北京大学微电子学研究所，北京  100871
Published: December 2020

The conduction mechanism of ultra-thin gate oxide n-metal-oxide-semiconductor fi eld effect transistor (n-MOSFET) after soft breakdown is studied in this paper. It is found that in a certain range of gate voltage Vg, the gate cur r ent Ig follows the Fowler-Nordheim-like tunneling mechanism, and the experimen tal tunneling barrier b is 0936 eV in average, which is much smal ler t han the interface barrier of Si/SiO2 We think that after soft brea kdown, the electrons existing in the quantization energy levels of the Si/SiO2 interface , not directly tunnel to the oxide conduction band, but tunnel to the oxide defe ct band. b is determined by both the defect band energy level and t he qu antization energy level of the tunneling electrons. With rising experimental tem perature, the tunneling of high energy level electron is also increasing, which reduces b gradually.
Study on electroluminescence spectra of InxGa1－xN/GaN-MQWs materials with high indium contents
Authors: Shao Jia-Ping  , Hu Hui  , Guo Wen-Ping  , Wang Lai  , Luo Yi  , Sun Chang-Zheng  , Hao Zhi-Biao  ,   清华大学电子工程系，集成光电子学国家重点实验室，北京  100084
Published: December 2020

In this work, the abnormal double-peak in the electroluminescence spectra of In xGa1-xN/GaN multiple quantum wells (MQWs) light emitting d iode s tructure materials with high indium contents was studied under different injecti on currents. The results show that the screening of internal electric field by i njection current plays an important role in the radiation recombination process of InxGa1-xN/GaN-MQWs materials.
Target ablation characteristics of thin films during nanosecond pulsed laser deposition in the ablation process
Authors: Tan Xin-Yu  , Zhang Duan-Ming  , Li Zhi-Hua  , Guan Li  , Li Li  ,   (1)华中科技大学物理系,武汉  430074; (2)华中科技大学物理系,武汉  430074;三峡大学物理系,宜昌  443002
Published: December 2020

The whole ablation process of target during the pulsed laser preparation of thin films is studied in this paper. An ablation model of targets in which the vapo rization is taken account is present based on the superheated theory. Different heat flux equations for different stages are then established. Finally, as usin g Si as the target, a finite difference method is employed to simulate the space _ and time_dependence of temperature in the target. Vaporization velocity and va porization thickness evolutions with different laser fluence are investigated. T he dependence of solid_liquid interface location S(t) on time which takes in to account the melting relaxation time is derived too. The results show that th e vaporization strongly affects the surface temperature in the pulsed laser abla tion. When the laser intensity reaches near the phase explosion energy threshold , the vaporization velocity and ablation depth will evidently decrease because o f the gas dynamic effects. This result is more appropriate than that obtained in previous works.
Microstructure induced by stress generated by high-current pulsed electron beam
Authors: Guan Qing-Feng  , An Chun-Xiang  , Qin Ying  , Zou Jian-Xin  , Hao Sheng-Zhi  , Zhang Qing-Yu  , Dong Chuang  , Zou Guang-Tian  ,   (1)大连理工大学三束材料改性国家重点实验室,大连  116024; (2)吉林大学材料科学与工程学院，超硬材料国家重点实验室,长春  130025
Published: December 2020

Face-center cubic metal materials including austenite stainless steel, aluminum single crystal and multi-grained pure aluminum were irradiated by a high-current pulsed electron beam (HCPEB) source in different processes. The deformed microstructures were observed by using scanning electron microscopy and transmiss ion electron microscopy. The relationship between stress characteristic and the microstructures has been analyzed. The current numerical simulations of the ther mal-mechanical process of HCPEB treatment were also investigated by comparing w ith the present experimental results. The present experimental results suggest t hat the value of the stress induced by HCPEB lies between 102—103MPa. The behavior of the stress propagation is closely related to the crystal structure of the material. This stress leads to the modification of the properties and the microstructures of the irradiated material in regions of greater depth.
Quantum area spectrum of Kerr black hole and the smallest mass of micro-black hole
Authors: Jiang Ji-Jian  , Li Chuan-An  ,   菏泽学院物理系，菏泽  274015
Published: December 2020

Kerr black hole has only two parameters of M and J. M and J, as the general coordinates, together with their conjugate variables form a four-di mensional phase space. The quantum area spectrum of Kerr black hole is obtained by performing gauge transformations, from which we can obtain the smallest mas s of Schwarzchild black hole.
Reduction of generalized Chaplygin systems
Authors: Mei Feng-Xiang  , Xu Xue-Jun  ,   (1)北京理工大学力学系，北京  100081; (2)北京理工大学力学系，北京  100081;浙江师范大学物理系，金华  321004
Published: December 2020

A generalized Chaplygin system is written in the form of containing the Lagrangian of the system which admits a reduction to an unconstrained system under certain conditions. This paper presents these conditions and two examples are given to illustrate the application of the result.
Synchronization of chaotic neural networks based on adaptive inverse control and its applications in secure communications
Authors: Yu Ling-Hui  , Fang Jian-Cheng  ,   北京航空航天大学第五研究室，北京  100083
Published: December 2020

Based on adaptive inverse control theory, a new chaotic neural networks synchron ous system and its secure communication are designed. The synchronization of cha otic neural networks system in the presence of perturbation is studied. The prop osed method can overcome effectively the noise pollution of channel in transmitt ing information. The numerical experiments show that the proposed secure communi cation scheme has advantages of flexible implementation, fast synchronization, h igh-quality recovery of information and large amounts of secret key for informat ion encryption.
Chaos control based on least square support vector machines
Authors: Liu Han  , Liu Ding  , Ren Hai-Peng  ,   西安理工大学自动化与信息工程学院，西安  710048
Published: December 2020

A new chaos control method based on Least-Square Support Vector Machines (LS-SVM) is proposed which has the excellent nonlinearity approximation ability and b etter generalization capability. Many chaotic systems can be composed into a sum of a linear and a nonlinear parts. LS-SVM has been applied in off-line identification of nonlinear part in continuous chaos system, and the identification mode l has been joined in system to compensate nonlinearity. Subsequently a linear st ate feedback controller has been developed to drive chaotic system to desirable points. It is proven by simulations for three representative continuous chaotic systems that the proposed method is effective to control the chaotic system and closed-loop system with state feedback, and the LS-SVM approximator is stable.
Coupled synchronization of the unified chaotic system
Authors: Min Fu-Hong  , Wang Zhi-Quan  ,   (1)南京理工大学自动化系，南京  210094;南京师范大学电气与自动化工程学院，南京  210042; (2)南京师范大学电气与自动化工程学院，南京  210042
Published: December 2020

This paper investigates the synchronization of two linearly coupled unified chaotic systems. A new sufficient condition of global asymptotic synchronization is attained from the theory of stability of time-varying systems. In addition, compared with the previously proposed method, the sufficient condition for the synchronization of two linearly coupled unified chaotic systems is simpler and le ss conservative, and the range of coupled coefficients is wider. Numerical simul ation shows the effectiveness and feasibility of this method.
On the mass of the ss member of the 31S0 meson nonet
Authors: Feng Xue-Chao  , Li De-Min  ,   郑州大学物理工程学院，郑州  450052
Published: December 2020

By using the two approaches, Regge trajectory and meson mixing, we estimate the mass of the isoscalar state ( composed mostly of ss— quarks) of the 3１Ｓ０ meson nonet. The two approa ches respectively give the values of 1853 MeV and 1849±12 MeV, which would be useful for searching for the candidate of this state experimently.
Polarization direction modulation for spin-polarized electrons with liquid crystal variable retarder
Authors: Ding Hai-Bing  , Pang Wen-Ning  , Liu Yi-Bao  , Shang Ren-Cheng  ,   清华大学物理系，极化物理实验室，北京  100084
Published: December 2020

The production of spin-polarized electrons and the modulation of polarization direction with liquid crystal variable retarder (LCVR) are discussed. The LCVR ca n play the roles of 1/4, 1/2, 3/4 and whole-wave plates with special voltages in the optical system. And the advantages of using LCVR instead of Pockels cell an d 1/4λ plate are the insensitivity to the incident photon direction, and the va riability of retardation over a large wavelength range without mechanical moveme nt. The polarization direction of spin-polarized electrons can be modulated easi ly by switching the helicity of the circularly polarized light. In order to dete rmine the photon polarization, the spinning polarimeter is developed. And the re sult is also described.
Theoretical calculation of vertical migration velocity for helium-radon cluster ions under ideal condition
Authors: Le Ren-Chang  , Lin Gang-Yong  ,   (1)东华理工学院电子工程系，抚州  344000; (2)福建师范大学物理系，福州  350007
Published: December 2020

The process in which the helium-radon clusters come into being was discussed.According to the traditional theory of mechanics,the theoretical calculation formula of vertical migration velocity for helium-radon clusters has been deduced.The maximal velocity and the time needed for the helium-radon clusters being accelerated to the maximal velocity are also given.
Absorption and dispersion of vegetable oil and animal fat in THz range
Authors: Hu Ying  , Wang Xiao-Hong  , Guo Lan-Tao  , Zhang Cun-Lin  , Liu Hai-Bo  , Zhang Xi-Cheng  ,   (1)美国伦斯勒理工学院应用物理与天文系，纽约州特洛伊市  12180-3590，美国; (2)首都师范大学物理系，北京  100037
Published: December 2020

Terahertz radiation generated by ultra short laser pulses has a broad band width in the far-infrared band.It is a new research field on terahertz wave interacting with materials,especially bio-materials.In this paper we studied five kinds of vegetable oil and two kinds of animal fats under different states using THz-TDS(THz time-domain spectroscopy).The refractive index and absorption coefficient of these materials are presented in the range from 0.2 to 1.6THz.The result hows that different oils have different refractive indices.The refractive indic es of vegetable oils have a gentle decline and the refractive indices of animal fats increase with temperature.The coefficients of absorption also increase with frequency.It's a meaningful result for the applications of biomedical sensing a nd imaging.
The microstructure and characteristics of luminescent porous silicon film prepared by the physicochemical sonic-vacating method
Authors: Liu Xiao-Bing  , Shi Xiang-Hua  , Liao Tai-Chang  , Ren Peng  , Liu Yue  , Liu Yi  , Xiong Zu-Hong  , Ding Xun-Min  , Hou Xiao-Yuan  ,   (1)长沙理工大学期刊中心，长沙  410076; (2)长沙理工大学物理与电子科学系，长沙  410077;复旦大学应用表面物理国家重点实验室，上海  200433; (3)复旦大学应用表面物理国家重点实验室，上海  200433; (4)湖南大学化学生物传感与计量学国家重点实验室，长沙  410082；长沙理工大学计算机与通信工程学院，长沙  410076; (5)西南师范大学物理系，重庆  400715
Published: December 2020

The special physicochemical environment caused by sonic_vacating provides an important outlet for the preparation of highly efficient luminescent porous silicon films.Experimental results show that sonic_chemical treatment is an effective t echnology for the improvement of the microstructure of porous silicon,and the luminescent efficiency and stability thereof.Luminescent porous silicon films,prep ared by ultrasonic-enhanced anode electrochemical etching,display better qualiti es than the samples prepared by conventionai methods widely used at present.This ultrasonic_chemical effect roots in sonic_vacating,i.e. the generation,formatio n and rapid collapse of bubbles in the etching solution.In the process of the po rous silicon being etched,the escape rate and caving_in of hydrogen bubbles in t he pores is increased as a result of the work of the ultrasonic waves,which is h elpful to the vertical etching of the pores.
Investigation of amplification characteristics of SRS in acetone enhanced by DCM dye fluorescence
Authors: Li Zhen-Sheng  , Cheng Juan  , Wang Zhi-Hua  , Luo Shi-Rong  , Yang Jing-Guo  ,   (1)四川大学物理系，成都  610064; (2)四川大学物理系，成都  610064;中国工程物理研究院激光聚变中心，绵阳  621900
Published: December 2020

The efficient amplification of stimulated Raman scattering in Acetone enhanced by dicyanomethylene(DCM) dye fluorescence and the amplification characteristics are reported in this paper. Under the various concentrations of DCM, various inte nsities of input Stokes signal and various pump laser intensities, the input and output Stokes wave intensities are measured in the experiment. At the concentration of 2×10-4 mol/L for DCM solution in ethanol, the bigg est enhan cement factor of Stokes wave reaches 57 The higher the intensity of pump l aser or input Stokes signal, the higher the intensity of output Stokes wave, an d if the input Stokes is too high, the enhancement coefficient may decrease, the so-called enhancement saturation.
Theoretical model and characteristics investigations of dual-channel optical chaotic communication system
Authors: Wu Jia-Gui  , Wu Zheng-Mao  , Lin Xiao-Dong  , Zhang Yi  , Zhong Dong-Zhou  , Xia Guang-Qiong  ,   西南师范大学物理学院, 重庆  400715
Published: December 2020

A theoretical model characterizing a recent experiment of dual-channel optical chaotic communication has been presented, and is proved to be reasonable by comparing the numerical simulation with the experimental results. After deducing the transmission function of semiconductor laser by small-signal analysis, how toreasonably select the system parameters in order to realize the effective transmission of signal has been specified. Moreover, the cross talk between two channels has been analyzed quantitatively. For a 250MHz modulation message, the nume rical simulation shows that it can be hidden efficiently during the transmission in the system and decoded easily.
Exact solution of the nonlinear “loop” soliton equation
Authors: Pu Li-Chun  , Zhang Xue-Feng  , Xu Li-Jun  ,   攀枝花学院数理教学部，攀枝花  617000
Published: December 2020

In this paper the author proposes a new method to solve the nonlinear “loop” soliton equation,that is,to directly find the solution of the analytic function U(ξ) of the equation by using the traveling wave parameter ξ and the power ser ies expansion, and to find the exact solution of the equation (including the sol itary wave solution) by directly observing the variation of the equation using M atLab to depict the functional relationship of U(ξ)-ξ for the cases of c→ligh t speed and c→sound speed.This method should be helpful in solving difficult no nlinear soliton equations.
Electron capture and violent acceleration by a tightly focused ultra-short ultra-intense laser pulse in vacuum
Authors: Tian You-Wei  , Yu Wei  , Lu Pei-Xiang  , He Feng  , Ma Fa-Jun  , Xu Han  , Jing Guo-Liang  , Qian Lie-Jia  ,   (1)复旦大学，上海  200433; (2)激光技术国家重点实验室，华中科技大学，武汉  430070;中国科学院上海光学精密机械研究所强光光学实验室，上海  201800; (3)中国科学院上海光学精密机械研究所强光光学实验室，上海  201800; (4)中国矿业大学(北京校区)，北京  100083
Published: December 2020

A low-energy relativistic free electron capture and violently acceleration by a tightly focused ultra-short ultra-intense laser pulse in vacuum is presented in this paper. The results show that the electron is mainly accelerated by the long itudinal ponderomotive force and the energy gain is sensitively dependent on the retarded time, initial energy and the incident angle of electron. On the other hand, the energy gain is not very sensitive to the pulse width when it is larger than 10λ.
Analysis of pseudospark pulsed electron beam shape in transmission
Authors: Liu Zhi-Jian  , Jiang Xing-Liu  , Le Xiao-Yun  , Wen Xiong-Wei  ,   北京航空航天大学理学院，北京  100083
Published: December 2020

The beam shape distortion of the pseudospark pulsed electron beam in transmissi on has been observed by the beam bombardment of the color changeable film and t he single crystal silicon. Based on the beam self-pinch effect, the mechanisms of the beam shape distortion have been analyzed by the theoretical calculation of the radial force of electron beam. The results showed that the elliptic beam shape was caused by the azimuthal magnetic field of transient currents, which past through the parallel charging capacitor, and the method for solving beam shape distortion in transmission was also presented.
Localized hexagonal structure in dielectric barrier discharge
Authors: He Ya-Feng  , Dong Li-Fang  , Liu Fu-Cheng  , Fan Wei-Li  ,   河北大学物理科学与技术学院，保定  071002
Published: December 2020

Stable localized hexagonal structure is obtained in Ar dielectric barrier discharge. Its spatiotemporal dynamics is measured. It is found that the discharge moment of the middle filament always precedes that of others. The interval between two adjacent discharges of one micro-discharge varies between a long interval an d a short one alternatively. The experimental results are analyzed and explained by a discharge model of wall charges. It is shown that the filament is affected not only by its own field but also by other filaments during the discharge.
Freezing of Cu nanoclusters studied by molecular dynamics simulation
Authors: Yang Quan-Wen  , Zhu Ru-Zeng  ,   中国科学院力学研究所非线性力学国家重点实验室，北京  100080
Published: December 2020

Freezing processes of liquid Cu nanoclusters with atoms of 147，309 and 561 are performed by means of molecular dynamics，which show that the structures of the obtained solid nanoclusters at room temperature are governed by the cooling rate and the clusters' sizes: the smaller clusters and the slower cooling rate bring the icosahedra structures more favorably, and contrarily， for the larger clust ers and the faster cooling rate，the face centered cubic structures will be expe cted in our simulation time. The physical mechanisms of this phenomenon are also discussed in this paper.
Study on the growth, modification and thermal properties of γ-LiAlO2 single crystals
Authors: Zou Jun  , Zhang Lian-Han  , Zhou Sheng-Ming  , Xu Jun  , Han  Ping  , Zhang Rong  ,   (1)南京大学物理系,南京  210093; (2)中国科学院上海光学精密机械研究所，上海  201800; (3)中国科学院上海光学精密机械研究所，上海  201800;中国科学院研究生院,北京  100039
Published: December 2020

Transparent and crack-free γ-LiAlO2 single crystal was grown by quic k Czochra lski technique. However, high melting point and easy volatilization degraded the quality of the crystal. The fall with at half maximum(FWHM) value dropped from 1169arcsec to 442arcsec when the crystal was modified by vapor transport equ ilibrium(VTE) technique. But when the temperature of VTE was 1300℃, the FWHM va lue increased to 552arcsec. The ［100］-orientation thermal expansion coeffici ent of the as-grown crystal was 176798×10-6/K, while that alon g the ［0 01］-orientation was 107664×10-6/K. After three VTE treatments , the cor responding thermal expansion coefficients decreased to 166539×10-6/K and 101784×10-6/K, respectively.
A study on the stacking fault in GaN crystals by high-resolution electron microscope imaging
Authors: Wan Wei  , Tang Chun-Yan  , Wang Yu-Mei  , Li Fang-Hua  ,   中国科学院物理研究所，北京凝聚态物理国家实验室，北京  100080
Published: December 2020

The stacking fault in crystals of GaN was studied by high-resolution electron microscope images in combination with image deconvolution. The principle of deconvolution for high-resolution electron microscope images is briefly introduced. It is demonstrated that an image originally does not intuitively reflect the examined crystal structure can be transformed into the structure image. The stacking faults in crystals of GaN were observed with the high-resolution microscope. The image deconvolution was performed for the image, and the atomic configuration in the defect core is seen clearly in the deconvoluted image. Based on this, the type of stacking fault has been determined. Besides, the effectiveness of image deconvolution in studying crystal defects is discussed.
Effects of lattice vibration on the effective mass of quasi-two-dimensional strong-coupling polaron
Authors: Eerdunchaolu  , Li Shu-Shen  , Xiao Jing-Lin  ,   (1)河北科技师范学院数理系，秦皇岛  066004; (2)内蒙古民族大学物理与机电学院，通辽  028043; (3)中国科学院半导体研究所，半导体超晶格国家重点实验室，北京  100083
Published: December 2020

The effects of lattice vibration on the system in which the electron is weakly coupled with bulk longitudinal optical phonons and strongly coupled with interfac e optical phonons in an infinite quantum well were studied by using Tokuda' line ar-combination operator and a modified LLP variational method. The expressions for the effective mass of the polaron in a quantum well QW as functions of the we ll's width and temperature were derived. In particular, the law of the change of the vibration frequency of the polaron changing with well's width and temperatu re are obtained. Numerical results of the effective mass and the vibration frequ ency of the polaron for KI/AgCl/KI QW show that the vibration frequency and the effective mass of the polaron decrease with increasing well's width and temperat ure, but the contribution of the interaction between the electron and the differ ent branches of phonons to the effective mass and the vibration frequency and th e change of their variation with the well's width and temperature are greatly di fferent.
Fractional spin in the O(3) nonlinear sigma model with Hopf and Maxwell-Chern-Simons terms
Authors: Zhang Ying  , Li Ai-Min  , Li Zi-Ping  ,   北京工业大学数理学院，北京  100022
Published: December 2020

The property of fractional spin of the O(3) nonlinear sigma model with Hopf and Maxwell_Chern_Simons (MCS) terms is studied. According to the rule of path integral quantization for a constrained Hamilton system in Faddeev_Senjanovic sc heme，the system is quantized. Based on the quantal Noether theorem，we get the quantal conserved angular momentum, and the fractional spin at the quantum level of this system is presented.
The dynamic control of the templates in selectivity growth from their isomers and the growth mechanism of CVD diamond
Authors: Ma Bing-Xian  , Jia Yu  , Yao Ning  , Yang Shi-E  , Zhang Bing-Lin  ,   郑州大学物理工程学院,郑州  450052
Published: December 2020

The key role of templates in the process of large-scale growth of ordered metastable phase and that of selectivity growth from their isomers with approximately equal free energy have been emphasized. Considering the rational elements in the existing models, the dynamics and thermodynamics theory for the growth process of diamond films have been given: 1) The chemical potential of carbon atoms is higher in the state of hydrocarbon gases than in the solid state. The carbon atoms in hydrocarbon gases may drop down to graphite or diamond surface that has a lower chemical potential. 2) The gas-state carbon atoms may change into the solid state through surface reactions. 3) The effect of surface of the template is a major factor for controlling the way of conversion of the gas-state carbon atoms. The different surfaces (surfaces with different orientations of graphite and diamond) can choose the different structure and energy state of the carbon atoms dropped onto them.4) Therefore, several kinds of different and independent surface reaction processes can occur at different sites of the substrate. These reactions correspond to the growths on different surfaces; 5) The orientation and velocity of these surface reactions are affected by the thermodynamic factors of neighboring surfaces. The direction of interaction determines whether growth or etching occurs for certain crystal surface. Growth of diamond and etching of graphite may be realized in a special range of temperature, of pressu re, of flow ratio of different gases. 6) The critical condition of nucleation wa s determined by the thermodynamic conditions such as local crystal lattice struc ture of the substrate, bonding structure, the gas temperature on the substrate s urface, pressure, the fractional pressure of different kinds of gases, and so on . 7) The plasma system that has energy exchange with the surroundings, and a ser ies of chemical reactions that occur in the gas phase can only provide the requi red non-equilibrium thermodynamic and chemical conditions to keep the growth of certain solid phase surface. The surfaces of diamond and graphite have the chara cter of template, they will dominate the epitaxy pattern of themselves. Heteroge neous substrates have certain local microstructure to play the role of a local t emplate for new phase nucleation. Different local microstructures caused by diff erent substrates, processing method and different chemical conditions will deter mine the orientation character,of the film.
UPS study of tri(β-naphthyl) phosphine overlayer on Ag(110)
Authors: Lu Yun-Hao  , Duan Xiao-Bang  , Lü Ping  , Zhang Han-Jie  , Li Hai-Yang  , Bao Shi-Ning  , He Pi-Mo  ,   (1)浙江大学化学系，杭州  310027; (2)浙江大学物理系，杭州  310027
Published: December 2020

Ultraviolet photoelectron spectroscopic(UPS) measurements of the tri (β-naphthyl) phosphine (TNP) film deposited on the Ag(110) surface were made. The TNP derived valence features are located at 38，63，93and 110 eV below Fermi level, and the top of the highest occupied molecular orbital(HOMO) of TNP is located at 25 eV in binding energy. The work function of Ag(110) is about 43 eV, and upon deposition of TNP, the work function decreases to the saturated value of 38 eV. Based on the UPS measurements, the energy level alignment at the interface of TNP/Ag(110) is given, and the results indicate a weak interaction between TNP and the Ag substrate.
Study on infrared absorption of interfaces in direct wafer bonded InP-GaAs structures
Authors: Lao Yan-Feng  , Wu Hui-Zhen  ,   中国科学院上海微系统与信息技术研究所信息功能材料国家重点实验室，上海  200050
Published: December 2020

Direct wafer bonded InP-GaAs structures are studied by FTIR infrared absorbance spectra and FESEM cross-sectional observations. Experiments show that the non-uniformity of bonding pressure during the fabricating step results in the appearance of a spacer-layer at the InP-GaAs interface. By melting wax and filling it into this spacer-layer, locally unbonded areas can be characterized upon the opt ical absorbance peaks at 3.509 μm. The 3.509 μm absorbance-intensity mapping images the non-uniform distribution of bonding pressure, which was obtained by t wo-dimensionally scanning measurement of infrared spectra of samples. Uniformly bonded InP-GaAs structures with uninterrupted interface are fabricated after imp roving the uniformity of pressure of fixture, which will be prospect of preparin g for large scale wafer bonding structures such as optical micro-cavity structur es.
Thermal stability of the magnetic tunnel junctions with nano-oxide layers
Authors: Feng Yu-Qing  , Hou Li-Na  , Zhu Tao  , Yao Shu-De  , Zhan Wen-Shan  ,   (1)北京大学技术物理系，北京  100871; (2)中国科学院物理研究所与凝聚态物理中心磁学国家重点实验室，北京  100080
Published: December 2020

The thermal stability is improved in a magnetic tunnel junction with a nano-oxide layer induced between the antiferromagnetic and pinned ferromagnetic layers, in which the annealing temperature is increased about 40℃. By using Rutherford backscattering spectroscopy, it has been found that the interdiffusion of Mn atoms, responsible for the decrease of TMR during the annealing process, is uppressed across such nano-oxide layer.
A method to estimate the strain state of SiGe/Si by measuring the bandgap
Authors: Cheng Bu-Wen  , Yao Fei  , Xue Chun-Lai  , Zhang Jian-Guo  , Li Chuan-Bo  , Mao Rong-Wei  , Zuo Yu-Hua  , Luo Li-Ping  , Wang Qi-Ming  ,   中国科学院半导体研究所，北京  100083
Published: December 2020

Using the result of model-solid theory,we have obtained the relationship between bandgap and strain of Si1-xGex alloy on Si(100) subs trate with x<085 . It was shown that the deviation between the bandgap of strained SiGe and relax ed SiGe is proportional to the strain. According to the theoretical result, a no vel method was suggested to determine the strain state of SiGe/Si through measur ing the bandgap. The strain in the SiGe/Si multi-quantum wells was measured using the new method and the results had good agreement with that from XRD measurement.