六角纳米颗粒LSPR性质及传感性能的理论研究

发布时间：2018-06-08 23:55

本文选题：六角星型纳米颗粒 + 六角花瓣纳米颗粒　；参考：《四川师范大学》2017年硕士论文

【摘要】：金属纳米颗粒由于其独特的局域表面等离子体共振(LSPR)性质,会呈现出一定的消光特性和局域场增强。基于这种性质,金属纳米颗粒可以被应用于LSPR传感、纳米波导和表面增强拉曼散射等多个领域。对于LSPR传感器,其传感性能主要由品质因数(FOM)体现,品质因数越高,传感性能越好。而品质因数与折射率灵敏度(RIS)和消光光谱的半高全宽(FWHM)直接相关,要得到好的品质因数,就要获得高的折射率灵敏度和窄的半高全宽。影响金属纳米颗粒LSPR性质的因素包括材料、尺寸、形状、排列方式以及周围介质的折射率等。近年来,人们从各个方面研究了金属纳米颗粒的LSPR性质和传感性能。无论是在理论计算上,还是在工艺制备技术方面都取得了显著的成果。但实验条件的限制,导致许多良好的理论成果难以实现。因此,本文在已有实验结果的基础上,提出了一种新型的六角金属纳米颗粒,用CST Microwave Studio仿真软件对其LSPR性质及传感性能进行研究。论文的主要工作和结果如下:1.研究顶角角度对六角星型Ag纳米颗粒LSPR性质和传感性能的影响。计算结果表明,当纳米颗粒的厚度和横截面积不变时,顶角角度逐渐从o20增大到o140,消光光谱的峰值波长蓝移,消光强度减弱。顶角角度的变化对折射率灵敏度的影响很大,但对消光光谱半高全宽的影响较小。当角度为o30时,折射率灵敏度达最大值1164 nm/RIU,品质因数为9.86 RIU~(-1)。实验中,经常无法达到理想的顶角角度,对于这种钝化情况,研究发现,随着顶角钝化程度的增加,品质因数相应减小,传感性能减弱。2.研究六角花瓣纳米颗粒的LSPR性质和传感性能。本论文首先计算了实验上容易实现的三明治(Ag/Mg F2/Ag)六角花瓣纳米颗粒的消光光谱。结果表明,随着介质层厚度的逐渐增大,短波长共振峰红移,而长波长共振峰蓝移;由上下金属层之间强烈的近场耦合导致的电场共振逐渐增强,磁场共振逐渐减弱;当介质层厚度为80 nm时,纳米颗粒的消光光谱只出现一个共振峰,此时半高全宽最小,获得的折射率灵敏度和品质因数分别为332 nm/RIU和3.91 RIU~(-1)。虽然改变介质层厚度可以调控LSPR光谱的峰值波长,但获得的传感性能并不理想。因此,为了获得更好的品质因数,本文计算了单层Ag六角花瓣纳米颗粒的消光光谱,并研究了其传感性能。通过对厚度和几何尺寸的一系列优化,折射率灵敏度能够达到668 nm/RIU,品质因数约为15 RIU~(-1)。
[Abstract]:Due to its unique local surface plasmon resonance (LSP) properties, metal nanoparticles exhibit a certain extinction characteristic and local field enhancement. Based on this property, metal nanoparticles can be used in many fields such as LSPR sensing, nano-waveguide and surface-enhanced Raman scattering. For the LSPR sensor, the sensing performance is mainly reflected by the quality factor FOM. The higher the quality factor, the better the sensing performance. However, the quality factor is directly related to the refractive index sensitivity (RIS) and the half maximum full width (FWHM) of the extinction spectrum. In order to obtain a good quality factor, a high refractive index sensitivity and a narrow half height full width must be obtained. The factors affecting the LSPR properties of metal nanoparticles include material, size, shape, arrangement and refractive index of surrounding media. In recent years, the LSPR properties and sensing properties of metal nanoparticles have been studied from various aspects. Remarkable achievements have been made in both theoretical calculation and process preparation technology. However, due to the limitation of experimental conditions, many good theoretical results are difficult to achieve. Therefore, based on the experimental results, a novel hexagonal metal nanoparticles is proposed in this paper. The LSPR properties and sensing properties are studied by CST Microwave Studio simulation software. The main work and results are as follows: 1. The effect of vertex angle on LSPR properties and sensing properties of hexagonal Ag nanoparticles was investigated. The calculated results show that when the thickness and cross-sectional area of the nanoparticles are constant, the angle of the peak angle increases from o20 to o140, the peak wavelength of the extinction spectrum shifts blue and the extinction intensity weakens. The change of the angle of the vertex has a great influence on the sensitivity of refractive index, but has little effect on the full width of the extinction spectrum. When the angle is o30, the refractive index sensitivity reaches the maximum value of 1164 nm / r IUU, and the quality factor is 9.86 RIU-1g. In the experiment, the ideal angle can not be achieved. For this passivation, it is found that with the increase of the degree of passivation, the quality factor decreases and the sensing performance weakens. The LSPR properties and sensing properties of hexagonal petal nanoparticles were studied. In this paper, the extinction spectra of hexagonal petal nanoparticles are calculated. The results show that with the increase of the thickness of the dielectric layer, the red shift of the short wavelength resonance peak and the blue shift of the long wavelength resonance peak, the electric field resonance caused by the strong near-field coupling between the upper and lower metal layers increases gradually, and the magnetic resonance gradually weakens. When the thickness of the dielectric layer is 80 nm, there is only one resonance peak in the extinction spectrum of the nanoparticles, and the half-height full width is the smallest, and the refractive index sensitivity and the quality factor are 332 nm / RIU and 3.91 RIU / 1 ~ (-1) respectively. Although the peak wavelength of the LSPR spectrum can be adjusted by changing the thickness of the dielectric layer, the sensing performance is not satisfactory. Therefore, in order to obtain better quality factor, the extinction spectra of monolayer Ag hexagonal petal nanoparticles were calculated and their sensing properties were studied. By optimizing the thickness and geometric size, the refractive index sensitivity can reach 668 nm / r ~ (-1), and the quality factor is about 15 ~ (-1) RIUs.
【学位授予单位】：四川师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB383.1;O485;TP212

【参考文献】