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Theoretical study on S_1(~1B_(3u)) state electronic structure and absorption spectrum of pyrazine

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Science china Chemistry 2008年第12期51卷 1166-1173页

作者： HE RongXing1, ZHU ChaoYuan 2, CHIN Chih-Hao3 & LIN Sheng-Hsien2,3 1 College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, china 2 Department of Applied Chemistry, institute of molecular Science and Center for Interdisciplinary molecular Science, National Chiao-Tung University, Hsinchu 300, china 3.institute of atomic and molecular sciences, academia sinica, taipei 106, china 1. College of Chemistry and Chemical Engineering Southwest University Chongqing 400715 China 2. Department of Applied Chemistry Institute of Molecular Science and Center for Interdisciplinary Molecular Science National Chiao-Tung University Hsinchu 300 China 3. institute of atomic and molecular sciences Academia Sinica Taipei 106 China

Making use of a set of quantum chemistry methods, the harmonic potential surfaces of the ground state (S0(1Ag)) and the first (S1(1B3u)) excited state of pyrazine are investigated, and the electronic structures of the two states are characterized. In the present study, the conventional quantum mechanical method, taking account of the Born-Oppenheimer adiabatic approximation, is adopted to simulate the absorp-tion spectrum of S1(1B3u) state of pyrazine. The assignment of main vibronic transitions is made for S1(1B3u) state. It is found that the spectral profile is mainly described by the Franck-Condon progression of totally symmetric mode ν6a. For the five totally symmetric modes, the present calculations show that the frequency differences between the ground and the S1(1B3u) state are small. Therefore the displaced harmonic oscillator approximation along with Franck-Condon transition is used to simulate S1(1B3u) absorption spectra. The distortion effect due to the so-called quadratic coupling is demonstrated to be unimportant for the absorption spectrum, except the coupling mode ν10a. The calculated S1(1B3u) ab-sorption spectrum is in reasonable agreement with the experimental spectra.

关键词： pyrazine absorption spectrum quantum mechanical method electronic structure

FINE STRUCTURES OF BOTH INTERFACES AND INTERFACIAL REACTION PRODUCTS

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Acta Metallurgica sinica(English Letters) 1993年第1期6卷 1-20页

作者： LI Douxing PING Dehai NING Xiaoguang YE Hengqiang Laboratory of atomic Imaging of Solids,institute of Metal Research,academia sinica,Shenyang.china Professor,institute of Metal Research,academia sinica,Shenyang 110015,china Inst of Metal Research Acad Sinica Shenyang China

The characteristic of interface depending on the atomic structure exerts an inportant,and sometime controlling,influence on performance of the interacial materials. The present paper reviews the main studies on fine structure of both the materials inter- faces and interfacial reaction products in semiconductor uperlattice,metal multilayer ceram- ics and composite materials by mean of selected area electron doffraction patterns and high resolution electron microscopy. The following features of interfaces are reviewed:the orientation relationships;the char- acteristic of steps,facets and ronghness of interfaces;atomic bonding across the interface;the degree of coherency,the structure of misfit dislocations and elastic relaxations at the inter- faces:the presence of defects at the onterfaces:the structure of the interfacial reaction prod- ucts as well as the reaction kinetics and reaetion mechanism.

关键词： fine structure of the interfaces interfacial solid state reaction orientation relationship high resolution electron microscopy

PREPARATION,PROPERTIES AND INTERFACE STRUCTURES OF Si_3N_(4w)/6061Al COMPOSITE

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Acta Metallurgica sinica(English Letters) 1992年第11期5卷 423-428页

作者： PAN Jin Changsha institute of Technology,Changsha,chinaNING Xiaoguang YE Hengqiang Laboratory of atomic Imaging of Solids,institute of Metal Research,academia sinica,Shenyang,china Changsha Inst of Technology Changsha China

The Si_3N_4 whisker reinforced 6061Al composite with bending strength of 790 MPa was prepared by squeeze casting *** heat-treatment under T6 regime i.e.530℃, 1 h solutioning and 160℃,24 h aging,an increment in strength and microhardness may be over 20% and 28% respectively,The microstructures of Si_3N_4 whisker and Si_3N_4/Al interface were observed by meas of *** relation between interracial structure and composite properties was discussed.

关键词： β-Si_3N_4 wthisker Al matrix composite strength interface

HIGH RESOLUTION STUDY OF TWINS IN Al_(20)Cu_2Mn_3 PHASE

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Acta Metallurgica sinica(English Letters) 1992年第4期5卷 227-230页

作者： LI Chunzhi WANG Shuncai JIN Yan institute of Aeronautical Materials,Beijing,Laboratory of atomic Imaging of Solids,institute of Metal Research,academia sinica,Shenyang,china Inst of Aeronautical Materials Beijing China

The dispersoid phase Al_(20)Cu_2Mn_3 in a 2024 Al alloy is commonly composed of twins,An ob- servation of corresponding high resolution image shows that the twin boundary plane is a glide plane other than mirror *** neighbouring components of twins are not symmetry of re- flection or rotation,but of glide ***“diamond”glide plane is(101)and the glide vector is(1/4)(-).Components of twins in the phase take shape of prism with the longitudinal edge being parallel to[010]and side faces being{101}and{100}.

关键词： twin glide reflection high resolution image Al-Cu-Mn alloy

PHOSPHORUS SEGREGATION AND ANNEALING EMBRITTLEMENT OF Ni-P AMORPHOUS

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Acta Metallurgica sinica(English Letters) 1991年第8期4卷 103-107页

作者： Qu Zhe XIE Tiansheng institute of Metal Research,academia sinica,Shenyang,china Acad sinica Shenyang China

Phosphorus segregation and embrittlement of Ni-P amorphous annealed at the temperatures below crystallization have been *** phosphorus enrichs on free surface and its level increases with annealing *** is fairly coincident with the measured toughness which decreases with annealing *** ion-sputtering revealed that a phosphorus depletion zone in the subsurface layers forms due to element redistribution during *** thickness and amplitude of the phosphorus depletion zone depend on the an- nealing temperature. The formation of depletion zone and the mechanism of embrittlement of Ni-P amorphous during annealing have been discussed based on the theory of the activation energy of atomic diffusion in the amorphous being variable.

关键词： Ni-P amorphous phosphorus segregation annealing embrittlement

STABLE NONLINEAR RELAXATIONS IN A MULTIPHASIC Al-Zn ALLOY

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中国有色金属学会会刊：英文版 1993年第2期3卷 58-64页

作者： Zhu,Xianfang institute of Solid State Physics,academia sinica,Hefei 230031,china

The experiments reveal the characteristics of stable damping in a multiphasic Al-Zn eutectoid alloy:（1）Thewhole damping(Q-1)has the same dependence on measured frequency（f）,i.e.Q-1ocf-n,where n is a parameterand is independent of temperature.（2）In a low-temperature（low-T）and low-strain-amplitude（low-A）region,Q-1=（B/）exp（-nH/kT）,where B is a parameter,H the atomic diffusion activation energy,k Boltzmann′sconstant,and T the absolute temperature.n,Ho（=nH）and H are all independent of A.The damping comesfrom an anelastic motion of the phase-interface.（3）In an intermediate region including a low-Tand a high-A,a middle-T and middle A and a high-T and low-A regions,the equation Q-1=（C/fn）exp（nH/kT）stillholds,but the damping has a normal amplitude effect C,n,and H all vary with A;the damping results from anonlinear relaxation of phase-interface.（4）In a high-T and high-A region,there is no longer a linear relationship between InQ-1 and T-1,whereas the relation Q-1f-n is still satisfied,where n increases as A increases,andthe damping has a normal amplitude effect but one which is weaker than that in the case（3）.The damping maybe attributed to another kind of nonlinear relaxation between phase-interfaces.

关键词： non-linear relaxations Al-Zn alloy damping

Quantitative amendment of high-field ^(13)C NMR spectra of coals

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Chinese Science Bulletin 1997年第10期42卷 807-809页

作者： YANG Baolian, LI Liyun and YE ChaohuiLaboratory of Magnetic Resonance and atomic and molecular Physics, Wuhan institute of Physics and Mathematics, Chinese Academy of sciences, Wuhan 430071, china Laboratory of Magnetic Resonance and atomic and molecular Physics Wuhan Institute of Physics and Mathematics Chinese Academy of Sciences Wuhan China

HIGH-RESOLUTION solid state 13C NMR spectroscopy has been a useful tool for the study of *** the use of cross polarization（CP）,magic angle spinning（MAS）and protonhigh-power decoupling（HPD）techniques,high-resolution solid state 13C NMR spectra ofcoals can be obtained and the coal aromaticity（fa）can be measured *** aromaticityis defined as the ratio of aromatic carbon atoms to the total carbon atoms in *** pa-

关键词： 13C NMR coal structure quantitative amendment.

PHASE STRUCTURE AND PROPERTIES OF EPOXY RESIN MODIFIED BY POLYSILOXANE BEARING PENDANT AMINO GROUPS

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Chinese Journal of Polymer Science 2000年第2期18卷 133-138页

作者： Bing Zhang Xiang-luan Liu Ying Huang Center of molecular sciences, institute of Chemistry, Chinese Academy of sciences, Beijing 100080, china Chinese Acad Sci Inst Chem Ctr Mol Sci Beijing 100080 Peoples R China

Polysiloxane-modified epoxy resins were prepared through the reaction of epoxy resin with polydimethylsiloxanes bearing pendant N-(beta-aminoethyl)-gamma-aminopropyl groups. The morphology and properties of the cured epoxy resins modified by the polysiloxanes were investigated. It was found that the phase structure and properties of the cured epoxy resins depend mainly on the amino group content in the polydimethylsiloxane and the level of the modifier. The change of phase structure in the cured epoxy resin systems was responsible for the dramatic change in their mechanical and surface properties.

关键词： phase structure polysiloxane epoxy resin mechanical property

SILICA-SUPPORTED NICKEL AND ZIRCONIUM CATALYSTS FOR BRANCHED POLYETHYLENE

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Chinese Journal of Polymer Science 2003年第4期21卷 453-458页

作者：孙文华 State Key Laboratory of Engineering Plastics The Center for molecular sciences institute of Chemistry Chinese Academy of sciences Beijing 100080 china Chinese Acad Sci Inst Chem Ctr Mol Sci State Key Lab Engn Plast Beijing 100080 Peoples R China

8-Aminoquinoline nickel dichloride and bis(cyclopentadienyl)zirconium dichloride (Cp_2ZrCl_2) were supportedsimultaneously on silica to produce branched polyethylene successfully by combined polymerization. The supportedpolymerization results showed that the molecular weight of polyethylene increased while the molecular weight distributionbecame wider and the molecular chains of oligomers remaning in the final solution became shorter as compared to theoligomers obtained in polymerization processes with pure 8-aminoquinoline nickel dichloride catalysis, as well as theCp_2ZrCl_2 and nickel combination system. With decreasing amount of Ni catalyst in the supported catalyst, the molecular chains of oligomers in the resulting solution became shorter, while α-olefin selectivity increased.

关键词： 8-Aminoquinoline nickel dichloride, Cp_2ZrCl_2 Silica supported catalysts Branched polyethylene