有序纳米线阵列在表面增强拉曼散射中的应用

发布时间：2018-01-22 18:56

本文关键词： 表面增强拉曼纳米线阵列局域表面等离激元重现性　出处：《南京大学》2015年硕士论文　论文类型：学位论文

【摘要】：表面增强拉曼(SERS)依靠“热点”,即电场强度极强的点,来激发分子的拉曼信号。这些热点通常由局域表面等离激元共振(LSPR)产生。尤其是在金属颗粒的间隙中,由LSPR耦合产生的电场跟原来相比可能达到108的增强,甚至能实现单分子探测。然而,极高的拉曼增强因子通常也会伴随着较低的重现性,从而限制了这种衬底的实际应用。本文首先分析了基于金属颗粒间局域表面等离激元的耦合的拉曼衬底里热点的产生,总结了其造成拉曼信号不均匀的原因。随后以银纳米颗粒包裹的有序排列的硅纳米线衬底为例介绍了人们的一些改进方案,并展示了通过聚苯乙烯球作为模板的金属催化化学刻蚀制备可控尺寸的有序硅纳米线阵列的工艺。然后,本文通过时域有限差分方法(FDTD)和光纤圆波导理论,得到了电磁表面波在不同材料的纳米线上的分布,并提出二氧化硅／硅核壳结构纳米线阵列来作为一种可以进一步提升拉曼信号重现性的解决方案。最后在二氧化硅／硅核壳结构纳米线上覆盖上银颗粒做成增强拉曼衬底(AgNPs@SiO2/SiNWs array),并通过大面积的逐点取样,证明了其极好的信号重现性。论文主要内容如下：1：回顾了之前以金属纳米颗粒间局域表面等离激元的耦合为热点的表面增强拉曼系统并总结了他们的共同特点。在分析了它们低重现性的原因后,我又介绍了银颗粒包裹的有序硅纳米线作为一种还未完善的提高重现性的解决方案。最后介绍了通过聚苯乙烯球作为模板的金属催化化学刻蚀制备可控尺寸的有序硅纳米线阵列的工艺,并展示了硅纳米线的表面形貌和其在SERS中的应用。2：通过FDTD的模拟和光波导理论,得到了电磁表面波在不同材料纳米线阵列上的分布。这种表面分布来源于纳米线阵列在633nm激光下激发的波导模式。它使得屯场能量在空间上重新分配,并成为最终提高衬底重现性的关键因素。基于这点我们最后提出二氧化硅/硅核壳结构纳米线作为最终的解决方案。3：我们制备了直径为150nm,长度1μm,周期为300nm的银纳米颗粒包裹的二氧化硅/硅核壳结构纳米线阵列。并与其它两种经典的表面增强拉曼衬底作对比,在大面积的逐点采样实验后,验证了我的衬底有着更好的重现性(相对标准偏差8%)和更高的增强因子。
[Abstract]:Surface enhanced Raman spectroscopy (SERS) relies on "hot spots", that is, points where the electric field is extremely strong. These hot spots are usually generated by the local surface isoexciter resonance (LSPRR), especially in the gap of metal particles. The electric field generated by LSPR coupling may be enhanced by 108, and even monolayer detection can be achieved. However, very high Raman enhancement factors are usually accompanied by low reproducibility. Therefore, the practical application of this kind of substrate is limited. Firstly, the generation of hot spots in Raman substrate based on the coupling of local surface isopherons between metal particles is analyzed. The reasons for the heterogeneity of Raman signal are summarized. Then some improved schemes are introduced taking the ordered arrangement of silicon nanowire substrates covered by silver nanoparticles as an example. The process of preparing controllable size ordered silicon nanowire arrays by metal-catalyzed chemical etching with polystyrene spheres as template was also demonstrated. In this paper, the distribution of electromagnetic surface waves on nanowires of different materials is obtained by FDTD) and optical fiber circular waveguide theory. The silicon dioxide / silica core-shell nanowire array is proposed as a solution to further improve the reproducibility of Raman signal. Finally, silver particles are coated on silica / silica core-shell nanowires to enhance the Raman signal reproducibility. Raman substrate (. AgNPs@SiO2/SiNWs Array. And through a large area of point-by-point sampling. Its excellent signal reproducibility is proved. The main contents of this paper are as follows:. The surface enhanced Raman systems which focused on the coupling of local surface isopherons between metal nanoparticles were reviewed and their common characteristics were summarized. The reasons for their low reproducibility were analyzed. I also introduce the ordered silicon nanowires coated with silver particles as an imperfect solution to improve reproducibility. Finally, we introduce the preparation of controllable size silicon nanowires by metal catalytic chemical etching of polystyrene balls as templates. Process of ordered Silicon nanowire arrays. The surface morphology of silicon nanowires and its application in SERS. 2: through the simulation of FDTD and optical waveguide theory. The distribution of electromagnetic surface waves on nanowire arrays of different materials is obtained. The surface distribution is derived from the waveguide mode excited by the nanowire array at 633 nm, which makes the field energy redistribution in space. Based on this we put forward silicon dioxide / silica core-shell structure nanowires as the final solution. 3: we have prepared 150 nm diameter. Silica / silica core-shell nanowire arrays with a length of 1 渭 m and a period of 300 nm were compared with the other two classical surface-enhanced Raman substrates. It is proved that my substrate has better reproducibility (relative standard deviation of 8) and higher enhancement factor after a large area point-by-point sampling experiment.
【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.1

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