碘掺杂聚乙炔电子自旋共振及导电性的研究

用四探针法测量掺碘聚乙炔薄膜[CH(I₃)_y]_x,当y=1.0％,4.2％和8.3％时面电阻随温度的变化,发现它们可用变程跳跃(VRH)模型很好的描述。用电子自旋共振(ESR)谱仪研究了不同温度下低浓度碘掺杂聚乙炔的自旋磁化率、峰峰宽等。并给出相应的理论解释。 关键词：     

反式聚乙炔的极化子静态性质研究

在Su-Schrieffer-Heeger（SSH）模型基础上,考虑长程电子关联的影响,研究反式聚乙炔分子链中空穴极化子与电子极化子的稳态性质。比较不同关联强度下两类极化子的晶格位形、能级、电荷密度波、以及吸收谱线的变化。加深对分子链中极化子的认识,该理论方法也可推广到高分子链中其它元激发的静态性质研究中,为不同类型元激发动力学性质研究奠定基础。     

两种可溶性聚乙炔衍生物的飞秒发光动力学研究

采用飞秒频率上转换技术测量了两种可溶聚乙炔衍射生物ｐｏｌｙ（ｐｈｅｎｙｌａｃｅｔｙｌｅｎｅ（ＰＰＡ）和ｐｏｌｙ（１－ｐｈｅｎｙｌ－１－ｂｕｔｙ１）ＰＰＢ）的发光动力学过程。采用非均匀展宽态密我规行走理论对上述结果进行了分析。     

DNA分子链的电子局域性质及电导的研究

将一维随机二元固体模型应用于DNA分子链，利用传输矩阵方法来研究系统电子态的局域性质并进而讨论系统的导电性质.对一个链长为50000个碱基对的DNA序列，数值分析了局域长度和电导随碱基对的摩尔百分数、本征能量和无序度的变化关系.结果表明，系统的局域长度和电导强烈地依赖于能量，在能带中心部分局域长度大于边沿部分.无序度也在一定程度上影响着局域长度，双方成反向变化的关系.对有限长度的DNA分子链，局域长度体现出明显的对碱基对摩尔百分数的依赖关系，对正常成分比例的随机DNA序列，在所有能量范围内系统的态都是局域的，系统的电导很小，系统呈现绝缘体行为.仅当一种碱基对在序列中所占比例很小时，系统中可以发现与特定分立能量值相对应的“扩展态”存在，处在这些态下的系统有较大的电导，但这些扩展态是不稳定的，在热力学极限之下会消失. 关键词： DNA分子链 电子局域 局域长度 电导     

丝光沸石的电导性能研究

测量了天然丝光沸石的总电导率和电子电导率,不同含水量时的电导率和活化能以及不同交换离子时的电导率和活化能.研究表明,丝光沸石在自然环境中具有10^-5-10^-6(Ω.cm)^-1的电导率,以离子电导为主.丝光沸石电导率的变化反映了它的结构变化. 关键词：     

反式聚乙炔链色散关系的维度效应

利用经典力学方法研究了二维反式聚乙炔链的光学模和声学模的维度效应.链的二聚化引起系统的对称性降低,从而导致光频支格波和声频支格波的宽度(ω2+(k=0)-ω2-(k=0))明显变窄,而对BZ边界面上两支格波的间隙(ω2+(k=π/a)-ω2-(k=π/a))几乎没有影响.     

电场作用下反式聚乙炔中孤子输运的数值计算

对于有电场存在下的反式聚乙炔单链中的孤子运动,用SSH模型引入电场项,通过数值计算,对孤子在电场下的运动规律进行了模拟．得到孤子在电场下沿链匀速运动的结论,     

Modeling of arbitrary cross-sectional cylinder using N circular cylinders for the scattering calculations

Exact solution of the electromagnetic wave scattering by N dielectric cylinders is presented by using matrix formulation. To check this present method, two comparisons between exact solutions for a single circular conducting and dielectric cylinder and this model composed of N=25 circular cylinders are made. Numerical results of conducting and dielectric square cylinder has been also checked with well-known result (B.E.M). The scattering patterns and the near field distributions in space are presented for the concave, convex and dielectric circular cylinder with conducting reflector.     

Electromagnetic beam wave scattering by arbitrary cross-sectional conducting cylinder using N circular cylindrical models

Rigorous expression of the electromagnetic beam wave scattering by N circular cylindrical models is described. To check this method, comparison between exact solution and this model composed of N=24 circular cylinders is presented for a single circular conducting cylinder. Numerical results of conducting square cylinder has been also checked with well-known result (B.E.M).     

基于紧密耦合理论的3端分子桥的传导特性

利用基于紧密耦合理论的格林函数方法，考虑到每一个碳原子的π轨道电子，对3苯环构成的纳米分子桥的量子传输特性进行了理论研究。得出了从分子桥的一个端点到另外两个端点的电子传输概率。 利用基于Fisher-Lee公式的流密度方法，在传输概率出现峰值的能量点E=±0.42, ±1.06 和±1.5处，计算了分子桥内部的电流分布。其数值结果用图形模拟表示出来。我们发现传输谱与入射电子能量相关，并且紧密地依赖与分子能级。其结果显示电子流分布完全符合Kirchhoff量子动量守恒定律。     

C50富勒烯分子的电子结构与传输特性研究

本文构建了Au原子面为电极的富勒烯C50分子的电子输运模型, 使用非平衡格林函数方法(Non-equilibrium Green's function, NEGF)对构建的Au电极和C50分子构成的分子器件进行了电子传输性质的计算. 通过计算得出了电子透射谱、电导曲线和电流电压曲线, 分析了产生这个分子器件电子输运性质的原因. 研究计算结果发现：C50分子具有量子器件的开关特性,并具有明显的半导体特征.     

圆孔的菲涅耳衍射

得到了圆孔菲涅耳衍射光强分布的表达式,此式由贝塞尔函数的数列(或Lommel函数)给出,因此很容易利用普及的数学软件算出结果.并且利用CCD照相机量度了衍射光强分布,与运算的结果作了比较,也与Burch在1985报导的结果作了比较.     

Conductance and Statistical Properties of Chaotic and Integrable Electron Waveguides

We show that the S-matrix for electrons propagating in a waveguide has different statistical properties depending on whether the waveguide cavity shape gives rise to chaotic or integrable behavior classically. We obtain distributions of energy level spacings for integrable and chaotic billiards shaped like the waveguide cavity. We also obtain distributions for Wigner delay times and resonance widths for the waveguide, for integrable and chaotic cavity geometries. Our results, obtained by direct numerical calculation of the electron wave function, are consistent with the predictions of random matrix theory.     

C20分子的一个电子输运模型研究

本文构建了Li链为电极的富勒烯C20分子的电子输运模型, 使用非平衡格林函数方法(Non-equilibrium Green's function, NEGF)对构建的Li电极和C20分子构成的分子器件进行了电子输运性质的计算. 计算得出了电子透射谱和电流电压曲线, 分析了产生这个分子器件电子输运性质的原因. 研究计算结果发现,大部分能量的电子是不会穿过器件的, 即使考虑不同偏压,能穿过器件的电子都集中在几个固定的能量上, 且在这几个固定能量上透过率比较高. 计算得出的伏安曲线说明在偏压为1.925V时电流达到最大, 只有在这个偏压周围才有相对明显的电流.     

聚乙炔的能带结构和长程关联能的计算

本文计算了在考虑电子-电子Coulomb相互作用情况下的导电聚合物聚乙炔的长程关联能(分周期边界条件和自然边界条件两种情况),与用其它方法得到的结果进行比较,结果符合很好,讨论了关联能对带隙的影响.     

The Conductance of a Mesoscopic Ring with a Quantum Dot

Employing the generalized Landauer-type formula and equations-of-motion technique, we present an analysis of the conductance for a mesoscopic ring with a quantum dot embedded in one of its arms. An explicit expression is obtained for the conductance of the device. The conductance, which is a function of single particle energy E' in the dot and the flux Φ through the ring, can be divided into three parts, G₁, G₂ and G₃. The second part G₂ is the most important term because it reflects the AB effect with a period of h/e. G₂ disappears in the vicinity of a conductance resonance of the system, which leads to a sudden phase shift by π. Moreover, under the condition of single-level approximation for the dot, we find that all resonances are in phase, which is in agreement with a recent experiment done by Yacoby et al. (Phys. Rev. Lett. 74 (1995) 4047).     

Second-harmonic generation circular dichroism spectroscopy from tripod-like chiral molecular films

The second-harmonic generation (SHG) circular dichroism in the light of reflection from chiral films of tripod-like chiral molecules is investigated.The expressions of the second-harmonic generation circular dichroism are derived from our presented three-coupled-oscillator model for the tripod-like chiral molecules.Spectral dependence of the circular dichroism of SHG from film surface composed of tripod-like chiral molecules is simulated numerically and analysed.Influence of chiral parameters on the second-harmonic generation circular dichroism spectrum in chiral films is studied.The result shows that the second-harmonic generation circular dichroism is a sensitive method of detecting chirality compared with the ordinary circular dichroism in linear optics.All of our work indicates that the classical molecular models are very effective to explain the second-harmonic generation circular dichroism of chiral molecular system.The classical molecular model theory can give us a clear physical picture and brings us very instructive information about the link between the molecular configuration and the nonlinear processes.