金属纳米结构的Fano共振在Nanoruler及增强拉曼散射中的应用

发布时间：2018-05-01 14:07

本文选题：表面等离激元 + Fano共振　；参考：《山东师范大学》2017年硕士论文

【摘要】：金属纳米结构的表面等离激元不仅有很多独特的性质,而且能够在纳米尺度上操控光,因而受到广泛关注。表面等离激元对金属结构的几何参数、对周围介电环境的变化非常敏感,而且在其周围可形成较强的局域电场,被广泛的应用于化学生物传感器、表面增强拉曼散射、荧光增强等方面。本文主要研究了基于金属纳米结构表面等离激元的Fano共振在Nanoruler以及在增强表面拉曼散射中的应用。金属纳米结构的Fano共振可形成谱线较窄的共振模式,对结构参数的变化更为敏感,而且会形成较强的局域电场,能够提高Nanoruler的探测灵敏度及增强拉曼信号的强度。主要完成的工作如下:(1)基于金属纳米结构的Nanoruler,一般是通过其支持的表面等离激元共振峰的移动去判别生物大分子等在纳米尺度范围内的变化。由于表面等离激元较宽的共振线宽,当结构间距或者几何参数改变时,共振峰的移动不易被分辨,从而导致其灵敏度不高。Fano共振可形成线宽较窄的共振模式,因此对于参数的变化非常敏感。本文第一个工作主要利用COMSOL软件设计了一个基于Fano共振的二维Nanoruler,通过计算表明它对于金属纳米结构之间的距离、旋转角度的变化都十分敏感。此结构由棒和矩形同心环盘结构组成。我们主要研究了矩形纳米盘移动时,对Fano共振峰及其深度的影响。当盘沿水平方向移动时,Fano共振的位置移动了 0.05eV,比其他结构灵敏度提高了 3-4倍。在竖直方向移动时,Fano共振的位置移动了 0.025eV。当盘旋转不同角度时,Fano共振的位置移动了 0.08eV。当将矩形环改为非对称结构时,我们还能判断出盘具体的移动和旋转方向。这大大提高了二维Nanoruler的灵敏度。(2)第二个工作主要研究了棒-棒结构及金属球-球结构所支持的Fano共振现象。通过调节棒的长度,或者当金属棒的厚度时,Fano共振都会随之发生移动。根据其移动规律,可以将此结构Fano共振移至633nm的拉曼激光波长处,这对我们实验有很好的指导作用。而对于双金属球的纳米结构,我们设计了大小不同的两个球。通过分别改变两个小球的直径以及两球之间的间距得到散射光谱随之变化的规律及电场分布图。通过电场分布图我们发现,随着小球直径的减小,拉曼的增强的热点增加。随后,我们通过高温退火的条件制备了金的双金属球的SERS基底,并对不同浓度的R6G溶液进行了检测。结果表明,此结构可提高拉曼散射的信号强度。
[Abstract]:The surface isoexcitons of metal nanostructures not only have many unique properties, but also can manipulate light at nanometer scale, so they have attracted much attention. Surface isoponitons are very sensitive to the geometric parameters of metal structures and can form a strong local electric field around them. They are widely used in chemical biosensors and surface enhanced Raman scattering (SERS). Fluorescence enhancement and so on. In this paper, the application of Fano resonance based on surface isoexcitons of metal nanostructures in Nanoruler and enhanced surface Raman scattering is studied. The Fano resonance of metal nanostructures can form a narrower resonance mode, which is more sensitive to the change of structural parameters, and can form a strong local electric field, which can improve the detection sensitivity of Nanoruler and enhance the intensity of Raman signal. The main works are as follows: (1) Nanoruler based on metal nanostructures is generally used to identify the changes of biomolecules in the nanoscale range by moving the resonance peaks of the surface isoexcitators supported by them. Because of the wide resonance linewidth of the surface isopotons, the shift of the resonance peak is not easy to be distinguished when the structure spacing or geometric parameters are changed, which leads to the low sensitivity of the resonance. Fano resonance can form a narrower resonant mode. Therefore, it is very sensitive to the change of parameters. The first work of this paper mainly uses COMSOL software to design a two-dimensional nanoruler based on Fano resonance. The calculation shows that it is very sensitive to the distance between metal nanostructures and the change of rotation angle. This structure consists of rod and rectangular concentric ring disk structure. We mainly study the effect of the rectangular nanodisk moving on the Fano resonance peak and its depth. When the disk moves horizontally, the position of Fano resonance shifts by 0.05 EV, which is 3-4 times higher than that of other structures. The position of Fano resonance moves 0.025 EV when moving vertically. The position of Fano resonance moves 0.08eV when the disk rotates at different angles. When the rectangular ring is changed to an asymmetric structure, we can also determine the specific movement and rotation direction of the disk. This greatly improves the sensitivity of two-dimensional Nanoruler. (2) the second work mainly studies the Fano resonance phenomena supported by the rod-bar structure and the metal-ball structure. By adjusting the length of the rod, or when the thickness of the metal rod, the Fano resonance will move with it. According to its moving law, the Fano resonance of this structure can be shifted to the Raman laser wavelength of 633nm, which is a good guide to our experiment. For the nanostructures of bimetallic spheres, we designed two spheres of different sizes. By changing the diameter of the two spheres and the distance between the two spheres, the law of the scattering spectrum and the distribution of the electric field are obtained. It is found that the hot spots of Raman enhancement increase with the decrease of the diameter of the sphere. Subsequently, the SERS substrate of gold bimetallic spheres was prepared by high temperature annealing, and the R6G solution with different concentrations was detected. The results show that this structure can improve the signal intensity of Raman scattering.
【学位授予单位】：山东师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB383.1

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