Dynamical study on charge injection and transport in a metal/polythiophene/metal structure

The dynamical process of charge injection from metal electrode to a nondegenerate polymer in a metal/polythiophene （PT）/metal structure has been investigated by using a nonadiabatic dynamic approach. It is found that the injected charges form wave packets due to the strong electron-lattice interaction in PT. We demonstrate that the dynamical formation of the wave packet sensitively depends on the strength of applied voltage, the electric field, and the contact between PT and electrode. At a strength of the electric field more than 3.0 × 10^4 V/cm, the carriers can be ejected from the PT into the right electrode. At an electric field more than 3.0 × 10^5 V/cm, the wave packet cannot form while it moves rapidly to the right PT/metal interface. It is shown that the ejected quantity of charge is noninteger.     

结构阻尼模型及系统时域动响应

振动界对经典的非频变结构阻尼模型一直有种种争议,本文检查了它的前提并指出将该模型推广到系统时域动响应分析时导致的悖论.为了提供结构阻尼系统的时域动响应实用分析方法,文中分别提出了基于响应优势谱成份的粘性阻尼近似模型和基于粘弹性理论的三参数频变结构阻尼模型;它们既可逼近结构阻尼缓频变的特性,又可保证系统的时域动响应具有因果性.     

Electronic,Vibrational, and Superconducting Properties of High-Pressure Metallic SiH4： ab initio Calculations

We extensively explore the experimentally proposed metallic structure of hcp P63 for the hydrogen rich compound, SiH4. It is found that the lattice dynamic of this structure is severely unstable. By freezing the soften mode, an orthorhombic Pbcn structure is discovered to be dynamically stable up to 226GPa. Within the conventional BCS theory, the calculated critical temperature Tc within the proposed Pbcn structure is 16.5K at 188GPa, in good agreement with the experimental result （17.5K）. Thus, we propose that the current predicted orthorhombic phase is a better candidate for the metallic phase of SiH4.     

银河系厚盘星族成分的新研究 *

利用最新校准的7个Basel天区的现代恒星计数和多色测光资料 ,对银河系的厚盘进行了全面的综合分析 ,得出了存在厚盘的有力证据 .在此基础上 ,对厚盘成分的结构参数值 ,光度函数 ,以及金属结构作了新的研究 .     

基于金属表面等离子激元控制光束的新进展

表面等离子激元(Surface plasmon polaritons,SPPs)是一种在金属-介质界面上激发并耦合电荷密度起伏的电磁振荡,具有近场增强、表面受限、短波长等特性,在纳米光子学的研究中扮演着重要角色。近年来表面等离子光学和基于SPPs的纳米光子器件的研究引起了国际上科学家们的广泛关注。讨论了SPPs的基本原理和在亚波长结构下的光学特性,介绍了基于亚波长金属结构的表面等离子激元在空间光束准直与聚焦、平面内光束聚焦与传导和在近场纳米光束的控制等方面的研究情况,以及在纳米光子学器件中的潜在应用。     

Hole arrayed metal-insulator-metal structure for surface enhanced Raman scattering by self-assembling polystyrene spheres

A fabrication process based on the self-assembling polystyrene spheres is proposed to obtain hole arrayed metal-insulator-metal （HA-MIM） structure for surface enhanced Raman scattering （SERS）. The localized field enhancement aroused by the gap resonance in the HA-MIM structure is analyzed by finite-different time domain （FDTD） method. With reference to the theory result, the structure is experimentally fabricated and the Raman scattering spectrum of rhodamine 6G （R6G） is measured by a miniaturized Raman spectrometer. The results shows that the enhancement factor is 3.85 times higher than the control sample with single layered metal hole array. The fabrication process to obtain the HA-MIM SERS substrate is reproducible, fast, large area and low cost.     

基于表面等离子激元的凸环结构金属-介质-金属滤波器设计

利用边界耦合的方法构造了金属-介质-金属结构滤波器,该结构由一个凸环谐振腔与一个波导管耦合而成.通过有限元法数值仿真得到了该凸环腔体波导结构的磁场分布图、透射谱线和谐振波长分布,分析了各结构参量对滤波器传输特性的影响.结果表明,所提出的凸环滤波器具有透射峰窄,谱线平滑等特点,且阻带透射率最低可达0.001,通带透射率最高可达0.977.增大结构参量h2和neff时,相应的透射谱会发生明显的红移,增大结构参量L1时,透射谱几乎无变化.对结构参量进行调整和优化,相应的谐振波长可分布在第一通信窗口(850nm)和第三通信窗口(1 550nm)附近,能够很好地运用于光通信中.     

隧道效应的转移哈密顿理论及隧道谱

本文介绍了金属-绝缘体-金属结构中隧道效应的转移哈密顿理论，讨论了非弹性隧道效应和弹性共振隧道效应以及它们的某些实验应用。最后简要介绍了近几年发展起来的一种新型表面分析技术——扫描隧道显微镜（STM）及其转移哈密顿理论给出的一些重要结果。     

基于几何曲面结构的金属狭缝阵列透镜研究

金属狭缝阵列透镜是一种通过激发和操控表面等离子体激元,突破衍射极限,实现光束调控的纳米光子器件。如何快速、高效地设计具有一定功能的金属狭缝阵列,并且在不影响器件功能的前提下,增大狭缝尺寸,使器件便于加工,是该类器件走向实际应用的关键问题。本文提出一种可以实现光束调控的新的金属狭缝阵列透镜的设计方法,将金属狭缝阵列作成几何曲面结构,可快速、高效地设计透镜,实现光束的调控作用。该方法设计的透镜,金属狭缝尺寸在80 nm,便于设计之后的加工制备,将加速纳米光子器件的实用化。     

Resonance Transport of Graphene Nanoribbon T-Shaped Junctions

We investigate the transport properties of T-shaped junctions composed of armchair graphene nanoribbons of different widths. Three types of junction geometries are considered. The junction conductance strongly depends on the atomic features of the junction geometry. When the shoulders of the junction have zigzag type edges, sharp conductance resonances usually appear in the low energy region around the Dirac point, and a conductance gap emerges. When the shoulders of the junction have armchair type edges, the conductance resonance behavior is weakened significantly, and the metal-metal-metal junction structures show semimetallic behaviors. The contact resistance also changes notably due to the various interface geometries of the junction.