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The study of two-color excitation upconversion of Pr(0.5)Yb(3):ZBLAN

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Science china(Physics,Mechanics & Astronomy) 2006年第2期49卷 169-177页

作者： CHEN Xiaobo1 & SONG Zengfu2.1. Applied Optics beijing Area Major Laboratory, Analysis and testing center, beijing Normal {2., beijing 100875, china 2. peking university, Physics School, beijing 100871, china Applied Optics beijing Area Major Laboratory Analysis and testing center Beijing Normal University Beijing China Physics School Peking University Beijing China

The excited state absorption upconversion of Pr(0.5)Yb(3):ZBLAN glass material, under two-color excitation of the 960 nm semiconductor laser and the Xe lamp light simultaneously, is reported in this article. It was found that the upconversion emission spectra of 480.1, 519.0, 601.9 and 631.8 nm coincide with the common emission spectra. Meanwhile, the upconversion-excitation spectrum has three obvious peaks under two-color excitation, and they respectively correspond to the 856.0 nm upconversion ex-citation transition [1G4(Pr3+)→1I6(Pr3+) and 1G4(Pr3+)→3P1(Pr3+)], the 789.0 nm upconver-sion excitation transition 1G4(Pr3+)→3P2.Pr3+), and the 803.7 nm upconversion excitation transition 3H6(Pr3+)→1D2.Pr3+). The upconversion excitation transition 1G4(Pr3+)→1I6(Pr3+) is strong because its oscillator strength f = 2..040×10?6 is large, which results in a large peak appearing in the upconversion excitation spectrum. That is just the new interesting two-color excitation upconversion luminescence phenomenon of Pr(0.5)Yb(3):ZBLAN induced by one laser and one continuous normal light simultaneously.

关键词： upconversion volumetric three-dimensional display two-color excitation.

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New color centers and luminescence of BaFI: Eu2.

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Science Bulletin 1997年第15期42卷 1268-1271页

作者： CHEN Wei and SU Mianzeng1. Laboratory of Semiconductor Materials Sciences, Institute of Semiconductor, Chinese Academy of Sciences, beijing 100083, china {2. Department of Chemistry,{{2., beijing 100871, china Laboratory of Semiconductor Materials Sciences Institute of Semiconductor Chinese Academy of Sciences Beijing China Department of Chemistry Peking University Beijing China

MANY publications have appeared on the photostimulated luminescence (PSL) of alkalineearth mixhalides. Color centers play a very important role in the PSL and X-ray storage imag-ing processes. The F centers, V centers and oxygen-related centers in this kind ofcrystals have been investigated. All these reports provide some useful information to the PSLmechanism and thus improve the practical applications of these materials. New color centers in

关键词： BaFI:Eu2. color centers photostimulated luminescence.

Electronic structure and magnetism of R(Fe,Si)_(12. (R=Y,Nd)

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Science china(Physics,Mechanics & Astronomy) 2006年第2期49卷 195-202页

作者： SUN Guang’ai1, CHEN Bo1, DU Honglin2. FAN Zhijian1, GAO Tao3 & QI Xinhua31. Institute of Nuclear Physics and Chemistry, china Academy of Engineering Physics, Mianyang 62.900, china 2. Department of physics,{2., beijing 100871, china 3. Institute of Atomic and Molecular Physics, Sichuan university, Chengdu 610065, china Institute of Nuclear Physics and Chemistry China Academy of Engineering Physics Mianyang China Department of physics Peking university Beijing China Institute of Atomic and Molecular Physics Sichuan University Chengdu China

The newly developed full-potential linearized augmented plane wave (LAPW) and local orbitals (lo) based on standard APW methods are briefly introduced, and the structure and magnetic properties of R(Fe, Si)12.compounds (R = Y, Nd) are calculated using the method. The distribution of Si at different sites is analyzed based on total energy of one crystal unit with structure having been optimized. The characters of magnetic mo-ments, total density of states (TDOS) and partial density of states (PDOS) for different crystal sites Si occupies are obtained and analyzed. The results show that the total mag-netic moments of RFe10Si2.(R = Y, Nd) are larger than those of RFe10M2.(M = Ti, V, Cr, Mn, Mo and W) and the hybridization mechanism is seen as follows. Si(8j) reduce the mag-netic moments of Fe at three sites, however, Si(8f) mainly reduce the magnetic moments of Fe(8i) and Fe(8j) atoms. The Curie temperature is markedly enhanced by the introduc-tion of Si atoms according to spin fluctuation of DOS at Fermi level.

关键词： (L)APW+lo method R(Fe Si)12.R = Y Nd) magnetic moment Density of state.

FRACTAL DIMENSION ANALYSIS APPLIED TO THE 7 DRAINAGE BASINS AND THE FLOOD IN china

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Natural Disaster Reduction in china 2003年第1期 33-36页

作者： Yang Xiuchun 1 and Zhu Xiaohua 2.(1. Key Laboratory of Environmental Change and Natural Disaster, Ministry of Education of china and Institute of Resources Science, {2. Normal {2., {2. 100875 2. College of Environment, peking university, beijing 100871, china) ZhuangYan

According to the fractal theory, the fractal dimensions of the 7 drainage basins and the flood are preliminarily calculated on the basis of GIS in this paper. The possible relation between the fractal dimensions of the 7 drainage basins and the flood is discussed. The following conclusions are obtained: fractal dimension is an useful parameter to depict the character of flood and it is of rich information indicating the frequency and period of flood; in the studied time period, if the numbers of flood in a drainage basin are relatively great, the fractal dimension of flood in this drainage basin is comparatively great, vice versa; when the fractal dimension of a drainage basin is relatively small, the fractal dimension of flood in this drainage basin is comparatively great, vice versa.

关键词： fractal analysis fractal dimension 7 drainage basins flood china

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Superconductivity in MgB2

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Progress in Natural Science:Materials International 2002年第11期 3-9页

作者： DAI Wen, FENG Qingrong and GAO Zhengxiang(1. Cryogenic Laboratory, Chinese Academy of Sciences, beijing 100080, china {2. Department of Physics,{{2., beijing 100871, china) Cryogenic Laboratory Chinese Academy of Sciences Beijing 100080 China Department of Physics Peking University Beijing 100871 China

In January of 2.01 the superconductivity of the compound MgB2.with a critical temperature Tc of up to 39 K was discovered. This Te is the highest in all intermetallic compound and alloy superconductors. MgB2.has a simple structure and its manufacturing capital cost is lower, therefore it could become a practical superconductor in the future. The recent progress is reviewed here which covers the progress in electronic structure, high 7% mechanism, superconducting parameters (Debye temperature, specific heat coefficient of electron, critical fields, coherent length, penetration depth, energy gap, critical current and relaxation rate of flux). Moreover the issue on power transmission is discussed.

关键词： MgB2 superconductivity electronic structure critical parameters electric transmission.

Hierarchical structures in climate and atmospheric turbulence

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Progress in Natural Science:Materials International 2002年第10期 29-34页

作者： SHE Zhensu, FU Zuntao, CHEN Jiong, LIANG Shuang and LIU Shida(1. State Key Laboratory for Studies of Turbulence and Complex Systems, Department of Mechanics and Engineering Sciences, peking university, beijing 100871,{{2. {2. School of Physics, peking university, beijing 100871,{{2. 3. LAPC, Institute of Atmospheric Physics, Chinese Academy of Sciences, beijing 1000{2.,{{2.) State Key Laboratory for Studies of Turbulence and Complex Systems，Department of Mechanics and Engineering Sciences，peking university，{{2. 100871，china LAPC，Institute of Atmospheric Physics，Chinese Academy of Sciences，beijing 10002.，{2. School of Physics，peking university，{{2. 100871，china State Key Laboratory for Studies of Turbulence and Complex Systems，Department of Mechanics and Engineering Sciences，peking university，{{2. 100871，china School of Physics，peking university，{{2. 100871，china

The climatic time series encompass many time scales, forming multi-scale climatic variations and hierarchies. The periods and magnitudes of cooling or warming, especially for extreme climatic events, vary with the time scales. On the other hand, high-frequency atmospheric turbulent motions, which are certainly related to the climatic changes, are also typical multi-scale phenomena. In this paper, certain properties of the fluctuations are examined that are invariant with the change of the time scales. Specifically, the existence of a statistical similarity law is demonstrated in climatic time series and in atmospheric turbulent motions. This is the hierarchical similarity law. Further analyses show that the hierarchical similarity law is a general property of multi-scale fluctuation systems. Therefore, the study on the hierarchical similarity law is important for understanding the inherent universal physical mechanism of complex systems in the atmospheric motions.

关键词： climate multi-scale hierarchical structure atmospheric turbulence.

Crystal structure and magnetism of the binuclear Gd(Ⅲ) complex Gd_2.C_12._8N_2._2.C_6H_5COO)_6

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Chinese Science Bulletin 2000年第8期45卷 706-711页

作者： NIU Shuyun , JIN Jing, JIN Xianglin, CONG Yao & YANG Zhongzhi1. Department of Chemistry, Liaoning Normal university, Dalian 11602.,{2. 2. Department of Chemistry,{2., beijing 100871,{2.

In the medium of H2., C2.5OH and HAC, the reaction of Gd(NO3)3-6H2. with C6H5COONa and C12.8N2.produced a novel binuclear Gd(Ⅲ) complex in formula [Gd2.C12.8N2.2.(C6H5COO)6]. Crystallographic data: crystal system, triclinic; space group, P l ; unit celi dimensions, α=1.191 9(2. nm, b =1.2.4 2.2. nm, c = 1.080 4(2. nm, α = 93.57(3)°, β= 113.33(3)°, y= 105.06(3)°, Z =1. The final R = 0.037 6. The magnetic measurement of the crystal powder in the temperature region of l .5-300 K shows that this complex possesses antifer- romagnetic property with fitting magnetic parameters .J = -0.471 and g =1.975.

关键词： binuclear Gd(III) complex crystal structure magnetism.

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