首页 | 本学科首页   官方微博 | 高级检索  
    检索          
共有20条相似文献,以下是第1-20项 搜索用时 109 毫秒

1.  Photoinduced Transformation between Charge Carrier and Spin Carrier in Polymers  
   梅元 赵昶 孙鑫《中国物理快报》,2006年第23卷第1期
   By dynamical simulations, we show a transforming process between neutral soliton (spin carrier) and charged soliton (charge carrier) in polymers via photo-excitation, taking a polaron as the transitional bridge. It is photoinduced transformation between spin carrier and charge carrier. In this way, we demonstrate an access for polymers to be applied to spintronics.    

2.  Photoexcitation of Bipolarons in Conducting Polymers  
   李盛 龙德顺 等《中国物理快报》,2002年第19卷第5期
   We theoretically study the photoexcitation process in a conducting polymer with a non-degenerate ground state,where the carrier with out spin is a bipolaron.The dynamical simulation reveals a photoinduced phenomenon in which a positive bipolaron is split into two polarons by absorbing one photon.The relaxation time of this photoinduced bipolaron split is about 40fs.It is predicted that this photoinduced phenomenon can be detected experimentally by observing the change of magnetic susceptibility.    

3.  A new perspective on optoelectric conversion in conjugated polymers  
   刘文  张明华  李海宏  王永娟  刘德胜《中国物理 B》,2011年第20卷第3期
   Photoexcitation of a neutral soliton will create a polaron and a charged soliton.According to a tight-binding model and a nonadiabatic method,we investigate the dynamical process of these two photogenerated charge carriers in an external electric field.It is found that the polaron and the soliton can pass through each other,which excludes the possibility of carrier recombination that usually occurs in existing organic solar cells.The results indicate a more efficient way to realize the optoelectric conversion by photoexciting polymer materials with soliton defects.On the other hand,it is found that solitons take on greater stability than polarons during collision.    

4.  Photoinduced Polaron-Splitting in Polymer  被引次数:1
   唐菲 徐晓华 孙鑫《中国物理快报》,2004年第21卷第8期
   We simulate a relaxation process of a polaron in polymer after photo excitation, and a new state is realized by means of proper excitation. The original lattice configuration of the polaron splits into two symmetrical peaks, and consequently a double-well potential is formed, where the wavefunctions of electron localized in these two wells are entangled. Thus, this process provides a method to generate the Schroedinger cat state. According to the dynamical process of the lattice configuration, the relaxation time of splitting is about 150fs.    

5.  The effect of interface hopping on inelastic scattering of oppositely charged polarons in polymers  
   邸冰  王亚东  张亚琳  安忠《中国物理 B》,2013年第6期
   The inelastic scattering of oppositely charge polarons in polymer heterojunctions is believed to be of fundamental importance for the light-emitting and transport properties of conjugated polymers. Based on the tight-binding SSH model, and by using a nonadiabatic molecular dynamic method, we investigate the effects of interface hopping on inelastic scattering of oppositely charged polarons in a polymer heterojunction. It is found that the scattering processes of the charge and lattice defect depend sensitively on the hopping integrals at the polymer/polymer interface when the interface potential barrier and applied electric field strength are constant. In particular, at an intermediate electric field, when the interface hopping integral of the polymer/polymer heterojunction material is increased beyond a critical value, two polarons can combine to become a lattice deformation in one of the two polymer chains, with the electron and the hole bound together, i.e., a self-trapped polaron-exciton. The yield of excitons then increases to a peak value. These results show that interface hopping is of fundamental importance and facilitates the formation of polaron-excitons.    

6.  Spin-Flip Process of Polarons in Conjugated Polymers with Magnetic Impurities  
   赵晖  张旭明  安忠  陈宇光  吴长勤《中国物理快报》,2009年第8期
   Being driven by an external electric field a polaron carrying both spin 1/2 and charge ±e moves at a constant speed in a polymer chain. When the polaron passes through a specific site, which couples to a magnetic impurity via spin-exchange interactions, its spin undergoes a spin-flip process if it is antiparallel to the impurity spin. Our numerical simulation shows that (a) a swap-like operation is performed between the polaron and impurity during the scattering process (b) polarons might be good candidates to be information carriers in the molecular scale.    

7.  Spin-Flip of Polaron in Polymers with a Magnetic Impurity  
   陈美娟 鄢永红 吴长勤《中国物理快报》,2007年第24卷第6期
   Using a nonadiabatic evolution method, we investigate the spin-flip process of polaron in polymers with a magnetic impurity. Our results show that when the spin orientation of this impurity is fixed to be perpendicular to the spin of polaron (θ = π/2), the magnetic impurity causes a spin-flip process. The probability of the spin-flip increases with the increase of exchange integral J up to about 0.35 eV and then decreases with the increase of J. In the case J is fixed while the spin orientation is adjustable, we find the probability of the spin-flip varies with the impurity orientation and reaches a maximum value at θ=π/2.    

8.  SAFETY CRITERION FOR PRESSURE WAVES  
   梁之安  冯俊明  孟昭辉  叶嗣茂  程明昆  周永申  李兴启  宋福治  王正国  郑世刚《Chinese Journal of Acoustics》,1983年第2期
   A safety criterion for pressure waves incident from the front was worked out on the bases ofnumerous animal experiments and ample verification in practical exposure cases in maneuvers withvarious weapons.The proposed safety criterion is expressed as p=177-6 long T.N,where p is thepeak pressure in dB re 2×10~(-5)Pa,T——impulse duration in ms,and N——number of roundson one exposure day.This safety criterion has been proved efficient in protecting 90% or moreof the exposed personnel from pressure wave injury.For normal incidence on the ear,p shouldbe decreased by 5 dB.    

9.  POLYMERIZATION OF p-DIETHYNYLBENZENE INITIATED BY Ni(C≡CC_6H_4C≡CH)_2(PPH_3)_2  
   Mu-jie Yang  Xiao-wei Zhan Department of Polymer Science and Engineering Zhejiang University Hangzhou 310027  China Present address: Institute of Chemistry  Chinese Academy of Sciences  Beijing 100080  China《高分子科学》,2001年第3期
   Homogeneous polymerization of p-diethynylbenzene initiated by nickel acetylide Ni(C ≡ C C_6H_4 C ≡ CH)_2(PPh_3)_2has been investigated in terms of different solvents, addition agents, atmosphere gases, catalyst concentrations, monomerconcentrations and polymerization temperatures. The yield and catalytic efficiency approach 88% and 11. 1 kg polymer/molNi, respectively, under the optimum conditions: [cat] = 0.01 mol/L, [M] = 1.0 mol/L, NEt_3/cat (mol ratio) = 3~5, 1,4-dioxane/toluene (volume ratio) = 1 and T = 25℃ for 5 h. The polymerization rate equation can be expressed as R_p =k_p[M][cat]~2, where k_p= 0.47 L~2. mol~(-2)·S~(-1) (25℃). The overall polymerization activation energy was found to be203 kJ·mol~(-1). Poly(p-diethynylbenzene) so obtained is soluble in THF, CHCl_3 and toluene with weight-average molecularweights as high as 27, 100 and a rich-trans extended π-conjugated polyene chain structure with pendent groups ofp-C_6H_4C≡CH.    

10.  Molecular Frame Photoemission: Probe of the Photoionization Dynamics for Molecules in the Gas Phase  
   D. Dowek  Y. J. Picard  P. Billaud  C. Elkharrat  J. C. Houver《化学物理学报(中文版)》,2009年第2期
   Molecular frame photoemission is a very sensitive probe of the photoionization (PI) dynamics of molecules. This paper reports a comparative study of non-resonant and resonant photoionization of D2 induced by VUV circularly polarized synchrotron radiation at SOLEIL at the level of the molecular frame photoelectron angular distributions (MFPADs). We use the vector correlation method which combines imaging and time-of-flight resolved electron-ion coincidence techniques, and a generalized formalism for the expression of the Ⅰ(χ, θe, Фe) MFPADs, where χ is the orientation of the molecular axis with respect to the light quantization axis and (θe, Фe) the electron emission direction in the molecular frame. Selected MFPADs for a molecule aligned parallel or perpendicular to linearly polarized light, or perpendicular to the propagation axis of circularly polarized light, are presented for dissociative photoionization (DPI) of D2 at two photon excitation energies, hv=19 eV, where direct PI is the only channel opened, and hv=32.5 eV, i.e. in the region involving resonant excitation of Q1 and Q2 doubly excited state series. We discuss in particular the properties of the circular dichroism characterizing photoemission in the molecular frame for direct and resonant PI. In the latter case, a remarkable behavior is observed which may be attributed to the interference occurring between undistinguishable autoionization decay channels.    

11.  Studies on odd-parity states of the Sm atom  
   关 锋  戴长建  赵洪英《中国物理 B》,2008年第17卷第10期
   Two-step excitation and ionization processes are used to detect Sm atoms in many excited states populated with tunable lasers. The wavelength of the first laser is tuned to the resonances from the Sm 4f^6 6s^2 ^7FJ (J=0 6) states to many odd-parity states with different electronic configurations, where the atoms are detected by photoionization process using an ultraviolet laser with a wavelength of 355 nm. Precise measurements on the energy level and intensity for many Sm 4f^6 6s6p and 4f^5 5d6s^2 states have been carried out. In a theoretical analysis on the spectral data, such as peak position, relative intensity, many transitions can be identified as the resonances from the Sm 4f^6 6s^2 7FJ (J=0-6) states to the atomic states with 4f^6 6s6p and 4f^5 5d6s^2 electronic configurations. This work also reports many spectral data on the odd-parity states that cannot be found in the literature.    

12.  HAUSDORFF DIMENSION OF THE DOUBLE POINT SET OF THE WESTWATER PROCESS  
   周先银《数学年刊B辑(英文版)》,1992年第1期
   Let X={X_i}_(t∈[0,1])be the Westwater process which is the coordinate process under3-dimensional polymer measure v(g)constructed by J.Westwater.In this paper,theHausdorff dimension problem for the double point set of X is investigated.As a result,it is proved thatdim D_2=1,v(g)-a.e.,where D_2={x∈R~3:X=X_(?)=x for some s    

13.  Effects of polarons on static order hyperpolarizabilities polarizabilities and second of conjugated polymers  
   王亚东  孟艳  邸冰  王淑玲  安忠《中国物理 B》,2010年第12期
   According to the one-dimensional tight-binding Su-Schrieffer-Heeger model, we have investigated the effects of charged polarons on the static polarizability, axx, and the second order hyperpolarizabilities, γxxxx, of conjugated polymers. Our results are consistent qualitatively with previous ab initio and semi-empirical calculations. The origin of the universal growth is discussed using a local-view formalism that is based on the local atomic charge derivatives. Furthermore, combining the Su Schrieffer-Heeger model and the extended Hubbard model, we have investigated systematically the effects of electron-electron interactions on αxx and γxxxx of charged polymer chains. For a fixed value of the nearest-neighbour interaction V, the values of αxx and γxxxx increase as the on-site Coulomb interaction U increases for U 〈 Uc and decrease with U for U 〉 Uc, where Uc is a critical value of U at which the static polarizability or the second order hypcrpolarizability reaches a maximal value of αxx or γxxxx. It is found that the effect of the e-e interaction on the value of αxx is dependent on the ratio between U and V for either a short or a long charged polymer. Whereas, that effect on the value of γxxxx is sensitive both to the ratio of U to V and to the size of the molecule.    

14.  Effects of polarons on static polarizabilities and second order hyperpolarizabilities of conjugated polymers  
   王亚东  孟艳  邸冰  王淑玲  安忠《中国物理 B》,2010年第19卷第12期
   According to the one-dimensional tight-binding Su-Schrieffer-Heeger model,we have investigated the effects of charged polarons on the static polarizability,α xx,and the second order hyperpolarizabilities,γ xxxx,of conjugated polymers.Our results are consistent qualitatively with previous ab initio and semi-empirical calculations.The origin of the universal growth is discussed using a local-view formalism that is based on the local atomic charge derivatives.Furthermore,combining the Su-Schrieffer-Heeger model and the extended Hubbard model,we have investigated systematically the effects of electron-electron interactions on α xx and γ xxxx of charged polymer chains.For a fixed value of the nearest-neighbour interaction V,the values of α xx and γ xxxx increase as the on-site Coulomb interaction U increases for U < U c and decrease with U for U > U c,where U c is a critical value of U at which the static polarizability or the second order hyperpolarizability reaches a maximal value of α max or γ max.It is found that the effect of the e-e interaction on the value of α xx is dependent on the ratio between U and V for either a short or a long charged polymer.Whereas,that effect on the value of γ xxxx is sensitive both to the ratio of U to V and to the size of the molecule.    

15.  The maximal Lyapunov exponent of a co-dimension two-bifurcation system excited by a bounded noise  
   Sheng-Hong Li and Xian-Bin Liu《Acta Mechanica Sinica》,2012年第28卷第2期
   In the present paper,the maximal Lyapunov exponent is investigated for a co-dimension two bifurcation system that is on a three-dimensional central manifold and subjected to parametric excitation by a bounded noise.By using a perturbation method,the expressions of the invariant measure of a one-dimensional phase diffusion process are obtained for three cases,in which different forms of the matrix B,that is included in the noise excitation term,are assumed and then,as a result,all the three kinds of singular boundaries for one-dimensional phase diffusion process are analyzed.Via Monte-Carlo simulation,we find that the analytical expressions of the invariant measures meet well the numerical ones.And furthermore,the P-bifurcation behaviors are investigated for the one-dimensional phase diffusion process.Finally,for the three cases of singular boundaries for one-dimensional phase diffusion process,analytical expressions of the maximal Lyapunov exponent are presented for the stochastic bifurcation system.    

16.  Analytical study of stationary soliton excitations in diamond-structure chain with quartic anharmonicity  
   XIA Qing-lin  ZHOU Guang-hui  YAN Jia-ren《原子与分子物理学报》,2001年第18卷第2期
   This work analytically study soliton excitations in an one-dimensional chain with the same mass but two alternating force constants between the nearest neighbors by means of multiple scales method plus quasi-discrete approximation. This model simulates a row of atoms in the 〈111〉 direction of a diamond-structure type of crystals. The explicit expressions of the stationary soliton solutions are obtained at some special wave vectors of the carrier wave (q=±π/a for acoustic mode and q=0, ±π/a for optical mode). The configuration of the atomic displacements of this model is different from that of diatomic chain with quartic anharmonicity.    

17.  Green-Light Electroluminescence of Conjugated Copolymer Containing p-Phenylene-ethynylene and Oxadiazole  
   YANG Mu-jie 1**  NIU Jun-feng 1  HILLER Markus 1  LIU Xu 2  YE Hui 2  FAN Xi-zhi 2 and CHEN Jun 21. Department of Polymer Science and Engineering  Zhejiang University  Hangzhou 310027  P. R. China   2. Department of Optical Engineering  Zhej《高等学校化学研究》,2002年第18卷第1期
   IntroductionSince the first report,in 1 990 ,of the electro-luminescence of the conjugated polymers in the filmof poly(p- phenylenevinylene) (PPV) sandwichedbetween an anode and a cathode of appropriatework functions[1] ,enormous efforts have been de-voted to the synthesis of light emitting poly-mers[2— 4 ] .Having been found potential applicationof conjugated polymers in photoluminescence(PL)and electro- luminescence (EL ) ,their importantproperties,polymer processability,band gap tun-abil…    

18.  Teleportation with an Arbitrary Mixed Resource as a Trace-Preserving Quantum Channel  
   SergioAlbeverio FEIShao-Ming《理论物理通讯》,2002年第37卷第3期
   Gerneral conditions are given in order to perform a perfect teleportation process in the case where the Hilbert spaces involved have different dimensiona,An explicit expression is obtained for the quantum channel associated with the standard teleportation protocol T0 with an arbitrary mixed state resource.The transmission fidelity of the corresponding quantum channel is given.    

19.  The Electroluminescence Characterization of Poly(p-phenyleneethynylene)——The π-conjugated Backbone Interrupted by a Butylene Unit  
   NIU Jun-feng and YANG Mu-jie ** Department of Polymer Science and Engineering  Zhejiang University  Hangzhou 310027  P. R. China《高等学校化学研究》,2002年第18卷第1期
   IntroductionSince the firstreport in1 990 of the electro- lu-minescence of the conjugated polymers in the filmof poly(p- phenylenevinylene) sandwiched betweenan anode and a cathode of appropriate work func-tions[1] ,enormous efforts have been devoted to thesynthesis of light emitting polymers[2— 4 ] .Owing toconjugated polymers′ photoluminescence and elec-troluminescence having been found out,their im-portant properties,polymer processability,bandgap tunability and mechanical flexibility mak…    

20.  Self-deflection of bright soliton in a separate bright-dark screening soliton pair based on higher-order space charge field  被引次数:1
   郝中华  刘劲松《中国光学快报(英文版)》,2003年第1卷第6期
   Based on the interaction of the separate soliton pair, the self-deflection of the bright screening soliton in a bright-dark pair is studied by taking the higher order space charge field into account. Both numerical and analytical methods are adopted to obtain the result that the higher order of space charge field can enhance the deflection process of the bright soliton and varying the peak intensity of the dark soliton can influence the self-deflection strongly. The expression of the deflection distance with the dark soliton's peak intensity is derived, and some corresponding properties of the self-deflection process are figured out.    

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号