【作者】 谷玥娇；

【导师】 徐蔚青； 徐抒平；

【作者基本信息】 吉林大学 ， 物理化学， 2014， 博士

【摘要】 表面等离子体是导体表面自由电子的集体振荡模式，是金属表面振荡电荷和入射光电磁场之间的共振作用形成的。它具有独特的光学特性并吸引着人们极大的兴趣。随着纳米技术的日益成熟，表面等离子体已经成为目前研究的热点，它的机制、效应及应用的研究和进展都受到了人们的关注。表面等离子体技术在生化传感，表面增强拉曼光谱等领域都已得到广泛的应用。而提高传感和表面增强拉曼光谱的检测灵敏度是表面等离子体技术在这两个领域中得到应用的关键。在本文中，我们将设计并制备具有纳米结构的表面等离子体基底，用于提高传感和表面增强拉曼光谱检测的灵敏度。主要内容包括以下三个方面：1.表面等离子体共振（SPR）传感器的灵敏度是衡量其性能的最主要参数，而表面等离子体产生的金属表面电磁场增强对SPR传感灵敏度的提高具有至关重要的作用。为了提高SPR传感器的灵敏度，我们在棱镜表面引入了纳米结构，采用了模板印刷和电化学沉积技术制备了周期性的银纳米碗阵列基底，通过表面电磁场强度的增加从而提高了SPR传感器的灵敏度。该研究为下一代高灵敏的SPR传感器设计提供了启发和新的思路。2.表面增强拉曼散射（SERS）是一种无损的光谱检测方法，可以提供关于分子结构的详细信息。SERS基底的增强能力是它是否可以进行高灵敏检测的核心因素。以实现高增强能力的SERS基底为目标，我们设计了一种表面等离子体纳米天线，这种天线构型由棱镜/银纳米井阵列构成。通过Kretschmann棱镜，对入射光的收集效率可以接近100%。利用纳米井阵列可以使收集到的入射光能量汇聚到近场，使金属表面的局域电磁场达到300倍的增强。同时，通过周期性的纳米井阵列也可以控制SERS信号的耦合发射方向，使SERS信号以垂直于基底的方向发射出来，从而有利于SERS信号的收集。该SERS基底的设计关键之处在于基于天线理论来同时提高能量的收集效率、能量的局域化汇聚能力、和能量发射效率。因此该模型在其它需设计光学元件的应用领域中都具有重要的应用潜力。3.从SERS的增强贡献来看，热点，即基底上具有非常高的电磁场的区域，在SERS的增强信号中占有主导地位。一般来说，人们常常可以在以下位置获得热点：距离很近的两个纳米粒子之间或突出表面的尖锐位置。在本研究中，区别于传统的间隙型和针尖型热点构型，我们提出了一种利用光波导和金属纳米粒子相结合的方法来聚集和增强局域电磁场强度进行SERS光谱检测。这种SERS基底结合了两种效应，一种是由光波导带来的波导共振效应，另一种是金属纳米粒子上的局域表面等离子体共振效应。在它们的共同作用下，可以使单个金属纳米粒子周围的电场强度增强~103，与热点的增强能力相差不多。且与一般热点相比，该体系中最强电场位于金属纳米粒子的两侧，更易于实现对化合物和生物大分子的高灵敏度检测。更多还原

【Abstract】 Surface plasmon is the collective oscillation of free electrons on metal surface,which is the result of the interaction of oscillation charge on metal surface and thefield of incident light. Surface plasmon has unique optical properties and has attractedgreat interests from people. With the increasing maturity of nanotechnology, surfaceplasmon has become the research hotspot. Its mechanism and application areintensively studied by researchers. Now surface plasmon has been widely applied inbiochemical sensing and surface enhanced Raman spectroscopy, in which thedetection sensitivity is the key issue. In this paper, in order to improve the sensing andRaman detection sensitivity, we design and prepare the surface plasmon substrate withnanostructures. The main contents include the following three aspects:1. The sensitivity of the surface plasmon resonance (SPR) sensor is the mostimportant parameter in evaluating its performance. In order to improve the sensitivityof SPR sensor, we introduce nanostructures on the prism surface. We prepare a silvernano-bowl array by using the template lithography and electrochemical depositiontechnique. The sensitivity of SPR sensor is improved by increasing the intensity ofsurface electromagnetic field.2. Surface enhanced Raman scattering (SERS) is a non-destructive spectrumdetection method, which can provide detailed information about molecular structures.The enhancing capacity of SERS substrate is the key issue in its high sensitivedetection. Here we design a surface plasmon nano-antenna, which is composed of aprism/silver nanowell array configuration. Through the Kretschmann prism, thecollection efficiency of the incident light is close to100%. The use of nanowell array can concentrate the collected light into nearfield, and produce a300timesenhancement in electric field intensity. In addition, through the nanowell array, we canalso control the SERS signal directional coupled emission for easy collection. In thedesign of this SERS substrate, the key issue lies in the improvement the collection andemission efficiency based on the antenna theory.3. For SERS enhancement contribution, hotspot, the regions on the substratewhich have intensive electromagnetic field plays a dominate role. Generally peoplecan often get hotspots in the following locations: positions between two nanoparticlesin close proximity, or sharp prominent surface. Here, different from the traditionalgap-or tip-type hotspot configuration, we propose a method combining opticalwaveguide and metal nanoparticles to enhance the local field intensity for SERSdetection. This SERS substrate has two enhancement contributions, one is from thewaveguide resonance, and the other is from the localized surface plasmon resonance.Under their combination effect, the local field around an isolated Ag nanoparticle canbe enhanced for about103times. Compared with general hotspots, in thisconfiguration the strongest electric field is located at the both sides of Agnanoparticles, which will have good performance in the detection of macromolecules.更多还原