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Science china Chemistry 2006年第6期49卷 492-498页

作者： QI Yuanhua1,2. GUAN Daren1 & LIU Chengbu1 1. Institute of Theoretical Chemistry, shandong university, jinan 2.0100, {2. 2. school of physics and microelectronics, shandong university, jinan 250061. china 1. Institute of Theoretical Chemistry Shandong University Jinan 250100 China 2. school of physics and microelectronics Shandong University Jinan 250061 China

The density functional theory (DFT) combining with the non-equilibrium Green functions (NEGF) method is applied to the study of the electronic transport properties for a Di-thiol-benzene (DTB) molecule coupled to two Au(111) surfaces. The dependence of the transport properties on the bias, the coupling geometry of the molecule-electrode interface, and the intermolecular interaction are examined in detail. The results show that the existence of the hydrogen atom at the end of the DTB molecule would significantly decrease the transmission coefficients, and then the differential conductance (dI/dV). By changing the position of the DTB molecule located between two electrodes a maximum value of calculated current is observed. It is also found that the intermolecular interaction will strongly influence the transport properties of the system studied.

关键词： non-equilibrium Green functions method, transmission spectrum, the molecular projected selfconsistent Hamiltonian, projected density of state.

Optical waveguides in LiNbO_3 and stoichiometric LiNbO_3 crystals by proton exchange

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Science china(physics,Mechanics & Astronomy) 2008年第10期51卷 1479-1488页

作者： LI ShiLing College of physics and Engineering, Qufu Normal university, Qufu 2.3165, {2. school of physics and microelectronics, shandong university, jinan 2.0100, {2. 1. College of physics and Engineering Qufu Normal University Qufu 273165 China 2. school of physics and microelectronics Shandong University Jinan 250100 China

The formation of optical planar waveguides in LiNbO3 and stoichiometric LiNbO3 crystals by proton exchange was reported. The prism-coupling method was used to characterize the dark-line spectroscopy at the wavelength of 633 and 1539 nm, re-spectively. The mode optical near-field outputs from proton-exchanged LiNbO3 and SLN waveguides at 633 nm were presented. The mode field from stoichiometric LiNbO3 (SLN) waveguide is lighter and more uniform than that from LiNbO3 waveguide, which means the quality of the waveguide in SLN crystal is better than that of the LiNbO3 waveguide. For proton-exchanged LiNbO3 waveguides, the evo-lution of the refractive index profile with annealing was presented. The disorder profiles of Nb atoms in proton-exchanged LiNbO3 waveguides were obtained by Rutherford backscattering/channeling technique. It is shown that the longer the exchange time, the larger the displacement of Nb atoms.

关键词： optical waveguide proton exchange LiNbO3 crystal stoichiometric LiNbO3 crystal

An investigation of hadronization mechanism at a Z^0 factory

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Science china(physics,Mechanics & Astronomy) 2010年第11期53卷 1998-2004页

作者： JIN Yi 1,SI ZongGuo 2.XIE QuBing 2.& YAO Tao 2.1 Department of physics,university of {2.,{2. 2.002.,china 2.school of physics,shandong university,{2. 2.0100,china 1. Department of physics University of Jinan Jinan 250022 China2. School of Physics Shandong University Jinan 250100 China

We briefly review the hadronization pictures adopted in the LUND String Fragmentation Model (LSFM),Webber Cluster Fragmentation Model (WCFM) and Quark Combination Model (QCM),*** of hadron multiplicity,baryon to meson ratios and baryon-antibaryon flavor correlations,especially those related to heavy hadrons at a Z 0 factory obtained by LSFM and QCM,are reported.

关键词： Z0 factory hadronization model baryon to meson ratio B correlation

Effects of Mg Doping on Photoconductivity of GaN Films

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Journal of Materials Science & Technology 2003年第6期19卷 575-577页

作者： Deheng ZHANG, Qingpu WANG and Yunyan LIUschool of physics and {2., shandong university, jinan 2.0100, china Sch. of Phys. and microelectronics Shandong Univ. Ji'nan 250100 China

This paper presents the UV photoconductivity properties of GaN films doped with different Mg concentrations deposited by MOCVD. It was observed that for the undoped and weakly doped GaN films the UV photocurrent response was relatively large and the relax time was relatively short. With an increase in doped Mg content, the samples became p-type, the photocurrent response became weak and the relax time became longer.

关键词： GaN UV photodetector Doping MOCVD

Ground state and polaron and bipolaron excited states in polydiacetylene

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Science china(physics,Mechanics & Astronomy) 2006年第4期49卷 430-439页

作者： LI Yuan1, HU Guichao1, XIA Caijuan1, LIU Desheng1,2.& XIE Shijie1,2.1. school of physics and {2., shandong university, jinan 2.0100, china 2. National Key Laboratory of Crystal Materials, shandong university, jinan 2.0100, china 1. school of physics and {2. Shandong University Jinan 250100 China 2. National Key Laboratory of Crystal Materials Shandong University Jinan 250100 China

The electronic properties of ground state and charged excited states of nondegenerate polydiacetylene were investigated by means of a tight-binding model. The parameters of the model were obtained by comparison of the experimental and other theoretical results. It was found that there is a stable dimerized structure of polydiacetylene in ground state and the doping induces the nonlinear excitations, such as polarons and bipolarons. In order to compare the stability of polaron and bipolaron, the creation energy and binding energy were separately defined. By neglecting the electron-electron Coulomb interaction, a bipolaron is more stable than two independent polarons.

关键词： dimerization, polaron, bipolaron, binding energy.

The influence of laser pulse on the photoabsorption spectra of Li atom in strong external field

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Science china(physics,Mechanics & Astronomy) 2006年第2期49卷 178-186页

作者： WANG Dehua1 & LIN Shenglu2.1. school of physics and Electronic Engineering, Yantai Normal {2., Yantai 2.402., china 2. Department of physics, shandong Normal {2., jinan 2.0014, china 1. school of physics and Electronic Engineering Yantai Normal University Yantai 264025 China 2. Department of physics Shandong Normal University Jinan 250014 China

Using the time-dependent perturbation theory and the calculation formula of the single- and double-pulse absorption spectra of the atom in strong external fields, we calculate the single- and double-pulse absorption spectra of Li atom in strong magnetic field for different pulse widths. The results show that a pulse of some width can reduce the contribution of the short period closed orbits and eliminate the contribution of the long period orbits. Compared with the single-pulse absorption spectra, we found that for some phase differences, the double-pulse laser absorption spectra are strengthened; while for others, they are reduced. Therefore, we can use the pulse laser to control the oscillation of the absorption spectra and obtain the optimization object.

关键词： laser pulse closed orbit absorption spectra.

An Improved parallel thinning algorithm with two subiter-ations

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Optoelectronics Letters 2008年第1期4卷 69-71页

作者： ZHANG Fen,WANG Yun-shan,GAO Cheng-yong, SI Shu-chun, and XU Jian-qiang school of physics and {2., shandong university, jinan 250061. china school of physics and {2. Shandong University Jinan China

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectively with single pixel width and the processing speed is high.

关键词：图像信号处理图像稀释平行稀释算法子迭代

Mechanical model of vulnerable atherosclerotic plaque rupture

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Science china(physics,Mechanics & Astronomy) 2004年第4期47卷 452-462页

作者： SU Haijun1, ZHANG Mei2.& ZHANG Yun2.1. school of Mathematics and System Science, shandong university, {2. 2.0100, china 2. Qilu Hospital, shandong university, {2. 2.0012. china 1. school of Mathematics and System Science Shandong University 250100 Jinan China 2. Qilu Hospital Shandong University 250012 Jinan China

Rupture of atherosclerotic plaque is the main trigger of acute cardiovascular events, but the mechanism of plaque rupture is still unknown. We have constructed a model describing the motion of the fibrous cap of the plaque using the theory of elastic mechanics and studied the stability of the plaque theoretically. It has shown that plaque rupture is the result of a dynamic interplay between factors intrinsic to the plaque itself and extrinsic factors. We have proposed a new mechanism of plaque rupture, given a new explanation about the nonlinear dynamic progress of atherosclerosis and suggested a method to identify the vulnerable plaques to manage atherosclerosis.

关键词： fibrous cap, parametric resonance, stability, mechanism, identification.

Exchange-coupling interaction, effective anisotropy and magnetic property of nano-magnetic materials

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Progress in Natural Science:Materials International 2007年第2期17卷 131-137页

作者： SUN Yan, GAO Ruwei, HAN Baiping, LIU Min, HAN Guangbing and FENG Weicun (school of physics and {2., shandong university, jinan 2.0100, china) [a]school of physics and {2. Shandong University Jinan China

The theories and models of exchange-coupling interaction between grains in nanocrystalline magnetic materials are introduced here. Their insufficiencies and distinctions from the experimental results are pointed out, and some revisions are made. The effects of the phase component ratio, the grain size and microstructure on the effective anisotropy and magnetic properties in the nanocomposite permanent materials and the improved models are discussed in detail.

关键词： nano-magnetic materials exchange-coupling interaction microstructure effective anisotropy magnetic property.

Electronic Structure of New Superconducting Perovskite MgCNi3

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Journal of Materials Science & Technology 2004年第2期20卷 203-205页

作者： Li CHEN, Hua LI and Liangmo MEIphysics and Microelectronic school,{2., jinan 2.0100, china Department of physics, Linyi Teachers university, shandong 2.6005, china Phys. and Microelectron. Sch. Shandong Univ. Ji'nan 250100 China Dept. of Phys. Linyi Teachers Univ. Linyi 276005 China

The electronic structures of new superconducting perovskite MgCNi3 and related compounds MgCNi2. (T=Co, Fe, and Cu) have been studied using MS-Xa method. In MgCNi3, the main peak of density of states is located below the Fermi level and dominated by Ni d. From the results of total energy calculations, it was found that the number of Ni valence electron decreases faster for the Fe-doped case than that for the Co-doped case. The valence state of Ni changes from +1.43 in MgCNi2.o to +3.02.in MgCNi2.e. It was confirmed that Co and Fe dopants in MgCNi3 behave as a source of d-band holes and the suppression of superconductivity occurs faster for the Fe-doped case than that for the Co-doped case. In order to explain the fact that Co and Fe dopants in MgCNi3 behave as a source of d-band holes rather than magnetic scattering centers that quench superconductivity, we have also investigated the effects of electron (Cu) doping on the superconductivity and found that both electron (Cu) doping and hole (Co, Fe) doping quench superconductivity exist. Comparing with the hole (Co) doping, there was no much difference between Cu and Co doping. This suggests that Co and Fe doping do not act as magnetic impurity.

关键词： Electronic structure Superconductivity Density of states