Remote excitation and remote detection of a single quantum dot using propagating surface plasmons on silver nanowire

Using propagating surface plasmons(SPs) on a silver nanowire(NW), we demonstrate that a focused laser light at the end of the silver NW can excite a single quantum dot(QD) microns away from the excitation spot. The QD–NW interaction allows the excited QD convert part of its energy into propagating SPs, which then can be detected at remote sites.Simultaneous multi-QD remote excitation and remote detection can also be realized. Furthermore, the tight confinement of the propagating SPs around the NW surface enables the selective excitation of QDs very close in space, which cannot be realized under the conventional excitation condition. This remote excitation and remote detection approach may find applications in optical imaging and the sensing of chemical and biological systems.     

单个等离激元纳米颗粒和纳米间隙结构与量子发光体的强耦合

在腔量子电动力学中,如果量子发光体与腔模式的耦合强度超过二者的平均损耗,就进入了强耦合区域,此时会形成部分光部分物质的新量子态—极化激元态.强耦合在室温玻色-爱因斯坦凝聚、极化激元激光、单光子非线性、量子信息等领域有重要的应用价值.基于单个金属纳米颗粒的结构可以支持局域表面等离激元共振,拥有极小的模式体积,非常有利于强耦合现象的发生.本文主要介绍了强耦合的理论背景、单个金属纳米颗粒和纳米间隙结构与量子发光体的强耦合、以及强耦合的动态调控,并展望了该领域的研究前景.     

Metallic nanowires for subwavelength waveguiding and nanophotonic devices

Plasmonics is a rapidly developing field concerning light manipulation at the nanoscale with many potential applications, of which plasmonic circuits are promising for future information technology. Plasmonic waveguides are fundamental elements for constructing plasmonic integrated circuits. Among the proposed different plasmonic waveguides, metallic nanowires have drawn much attention due to the highly confined electromagnetic waves and relatively low propagation loss. Here we review the recent research progress in the waveguiding characteristics of metallic nanowires and nanowire-based nanophotonic devices. Plasmon modes of both cylindrical and pentagonal metallic nanowires with and without substrate are discussed. Typical methods for exciting and detecting the plasmons in metallic nanowires are briefly summarized. Because of the multimode characteristic, the plasmon propagation and emission in the nanowire have many unique properties, benefiting the design of plasmonic devices. A few nanowire-based devices are highlighted, including quarter-wave plate, Fabry-Prot resonator, router and logic gates.     

Electromechanical Behavior of Interdigitated SiO2 Cantilever Arrays

Bending and first flexural mode vibration behavior of electrostatic actuated nanometer-sized interdigitated cantilever arrays are characterized under vacuum conditions. The pull-in＇＇ effect in dc driving and the hard spring effect＇＇ in ac driving are observed. A mass sensitivity of 20 fg is expected for our devices due to the ultra-small mass of the arm and relative high Q factor. The mass-spring lump model combined with Green＇s function method is used to fit the dc driving behaviors including the pull-in voltage. For the ac driving case, the polynomial expansion of the capacitive force is used in the model. The successfully fittings of the pull-in voltage and the hard spring effect prove that our simulation method could be used for guiding the geometrical design of cantilever-based sensors.     

热辅助下的在线甲基衍生化-气相色谱法分析银杏叶中的银杏酸

采用热辅助下的在线甲基衍生化-气相色谱法测定银杏叶中的银杏酸。银杏叶样品与衍生化试剂四甲基氢氧化铵(TMAH, 25%甲醇溶液)同时进样,在300 ℃的进样口瞬间生成了银杏酸甲基衍生物,银杏叶中6种银杏酸得到很好的分离。在一定的质量浓度范围内银杏酸的线性关系良好,回归系数均大于0.9966,最低检出限范围为0.8～2.8 mg/kg。银杏叶中主要的烷基酚类物质为银杏酸C13∶0,C15∶1和C17∶1,它们的含量(用质量分数表示)分别为11.0%,36.7%和42.8%,3次平行测定的相对标准偏差(RSD)均小于3.4%(n=3)。银杏叶样品中总银杏酸的含量为4.0～10.9 mg/g。该方法无需繁琐费时的衍生化和纯化等前处理步骤,不失为银杏叶中银杏酸测定的一种快速、简便、准确的方法。     

表面等离激元——机理、应用与展望

等离激元光子学(plasmonics)的研究内容是金属纳米结构独特的光学性质及其应用.随着纳米科技的进步,等离激元光子学已经迅速发展成为一门新兴学科,在生物、化学、能源、信息等领域具有重要的应用前景.文章主要介绍表面等离激元(surface plasmons,SPs)的一些基本物理性质,包括局域的表面等离激元(localized surface plas-mon,LSP)和传导的表面等离激元(propagating surface plasmon polariton,SPP),文章还介绍了表面等离激元的几个重要的应用方向,例如生物/化学传感器、表面等离激元激光、光开关器件以及表面等离激元光逻辑运算,等等.     

High-order plasmon resonances in an Ag/Al2O3 core/shell nanorice

Using numerical simulation, we investigate the high-order plasmon resonances in individual nanostructures of an Ag nanorice core surrounded by an Al2O3 shell. The peak positions of localized surface plasmon resonances （LSPRs） are red-shifted exponentially with the increase of the dielectric shell thickness. This is due to the exponential decay of electromagnetic field intensity in the direction perpendicular to the interface. This exponential red-shift depends on the wavelength of the resonance peak instead of the resonance order. In addition, we find that the LSPRs in an Ag nanorice of 60-nm width can be perfectly described by a single linear function. These features make nanorice an ideal platform for sensing applications.     

用GC/MS研究含α-活泼氢芳烃与硝基苯的反应

在常温常压下，研究了苊、蒽、萘、芴、1-甲基萘（1-MN）、2,6-二甲基萘（2,6-DMN）、苯酚、α-萘酚与PhNO2(硝基苯)在Lewis酸AlCl3催化作用下的反应。结果发现，蒽、萘和苯酚与PhNO2不反应，苊、芴、1-MN、2,6-DMN和α-萘酚与PhNO2都能反应生成相应的苯胺基芳烃。GC/MS分析表明反应活性顺序为苊＞1-MN＞2,6-DMN＞芴，根据超共轭效应可以合理解释含α-活泼氢芳烃反应活性顺序。控制AlCl3与苊的摩尔比值为1.2和2.4左右，重结晶苊与PhNO2的反应产物分别得到联苊和5-苯胺基苊纯品，利用GC、GC/MS、FTIR和UV等分析测试手段对其进行了结构鉴定。     

Quantization Scheme of Surface Plasmon Polaritons in Two-Dimensional Helical Liquids

The collective modes of two-dimensional helical electron gases interacting with light have been studied in an extended random phase approximation.An inverse operator transformation that interprets electron oscillations and photons with quasi particles is developed.Because photons are initially included in the model,one can directly derive and compare the static and radiation(or vector)Helds for the excited collective modes.Unlike the traditional quantization scheme that the electron oscillation's contribution is totally hidden in the dielectric function,we can directly investigate their roles when the collective modes interact with other particles.As an example,we find an additional term which plays an important role at small distance arising from electron exchanging effect when the collective modes couple to emitters.     

拉曼光谱在锂离子电池研究中的应用

综述拉曼光谱(Raman spectroscopy)在锂离子电池碳负极材料、尖晶石LiMn2O4和LiFePO4正极材料、聚合物和室温熔盐电解质以及电极/电解质界面膜研究中的应用,分析了非原位拉曼测试手段与原位拉曼测试手段的优缺点,展望了这一领域目前有待解决的问题和可能应用的新技术.