【作者】 陈佳宁；

【导师】 徐洪起； 徐红星；

【作者基本信息】 大连理工大学 ， 凝聚态物理， 2008， 博士

【副题名】从纳米线表面增强拉曼散射传感器到双针尖增强拉曼散射光谱

【摘要】 等离子体子(Plasmon)是导体中自由电子集体的电磁振荡量子化后得到的准粒子。表面等离子体子(Surface Plasmon)则是限制在导体表面的等离子体子。如果导体自身尺度非常小或者导体有细微的表面结构,并且其尺寸远小于光波长,那么在光场照射下这类表面上激发出的表面等离子体子将被限制在特定的表面结构处,形成叫做局域表面等离子体子(Localized Surface Plasmon)。与光滑导体表面上存在的表面等离子体子不同,存在于纳米尺度导体结构上的局域表面等离子体子可以与光子产生强耦合共振,从而在导体纳米微结构表面产生一个局域的增强电场。金属纳米结构在激发光照射下在纳米结构表面产生局域增强电场的现象有很多应用,表面增强拉曼散射(Surface-enhanced Raman Scattering)和针尖增强拉曼散射(Tip-enhanced Raman Scattering)是其中两个非常重要的方面。表面增强拉曼散射是利用存在于金属纳米结构中的增强电场放大吸附在金属表面分子的拉曼散射信号:而针尖增强拉曼散射则是利用存在于扫描探针显微镜的金属针尖处的局域增强电场来放大吸附在样品表面分子的拉曼散射信号。由于扫描探针激发而得的光谱信号的来源被限制在针尖下部有限范围内,随着针尖在样品表面上的移动就可以得到表面不同位置的光谱信息,这样就突破光波长的极限实现分辨纳米尺度量级的光学信息。本论文第一章概述等离子体子和表面等离子体子的一些概念、性质和相关研究状况;第二章介绍表面增强拉曼散射的原理及相关应用并对纳米线阵列中表面增强拉曼散射的光偏振依赖性进行了研究;第三章介绍针尖增强拉曼散射的相关信息,研究了“双针尖”耦合形式的针尖增强拉曼散射光谱,并对针尖增强拉曼散射研究中出现的各种现象进行了讨论。第四章介绍用扫描隧道显微镜对金表面上的纳米颗粒和吸附的分子所进行的一些研究。更多还原

【Abstract】 Plasmons are quasiparticles resulting from the quantization of collective oscillations of the free charges in a conductive medium, and surface plasmons are plasmons which are confined to the surface of the conductive medium. The surface-plasmon polaritons (SPP) are quasipartcles formed when the suface plasmons are coupled with photon field. If the surface of a metal exhibits tiny structures or the size of a metal partcle is much smaller than the wavelength of the excitation light, the excited surface plasmons will be bounded to the tiny structures of the metal or the metal particle, leading to the formation of localized surface plasmons (LSPs). The LSPs can be excited by light and, in a resonant condition, a vast locally enhanced electromagnetic field can be created in the vicinity of the nanometer sized metal structures. Localized surface plasmon resonance (LSPR) on nanometer sized metal structures has many usages, of which two important ones are surface-enhanced Raman scattering (SERS) and tip-enhanced Raman scattering (TERS). The mechanisms of SERS can be ascribed to the electromagnetic enhancement part and the chemical enhancement part. For the former one, the locally enhanced electromagnetic field coherently amplifies both the excitation and the emission of absorbed molecules, resulting in the enhancement of the Raman signal. TERS has an advantage over the SERS in the sense that it not only provides the Raman signal enhancement with presence of the sharp tip, but also provides high spatial resolution topographic and near-field optical informations simultaneously.The thesis is organized as follows. Chapter 1 presents the introduction to the concepts of plasmons and SPPs with examples. Chapter 2 discusses SERS related issues and gives details about the polarization dependence of SERS on gold nanoparticle-decorated nanowire arrays. Chapter 3 describes TERS related issues with an emphasis on the technology developments. Finally, in Chapter 4, an STM study of gold surfaces and gold surface reconstructions due to particle depositions and molecule adsorptions is presented.更多还原