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Localized Surface Plasmons Resonance Sensing Properties of Metal Composition Nanoparticles

Author: LiuJuanYi
Tutor: LiuYunLin；LuoXianGang
School: Southwest Jiaotong University
Course: Electromagnetic Field and Microwave Technology
Keywords: Metal composite nanostructures Localized surface plasmon resonance Discrete dipole approximation Finite Difference Time Domain Refractive index sensitivity
CLC: TB383.1
Type: Master's thesis
Year: 2010
Downloads: 281
Quote: 0
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Abstract

Metal nanoparticles localized surface plasmon resonance biosensing is one of the hot. The sensor has a low manufacturing cost, easy to carry the advantages, but its low detection sensitivity study focused on how to improve the detection sensitivity of the sensor. Wherein the refractive index of the metal nanoparticles sensitivity is one of the important parameters of the sensor detection sensitivity. Different materials having different electromagnetic properties, and will therefore be different composite materials can be adjusted the nanoparticles localized surface plasmon resonance characteristics can be used as an effective method to improve the refractive index sensitivity of the nanoparticles. This paper presents two composite nanostructures and their localized surface plasmon resonance characteristics of a study. Gold nanoparticles chemically stable and strong affinity of biomolecules, but the lower refractive index sensitivity, contrary to silver nanoparticles. The combination of the two, not only can improve the sensitivity of the refractive index of the nanoparticles, the excellent characteristics conducive sensing can also be reserved. Based on this rectangular desk covered with a layer of gold above a silver layer composite nanostructures using discrete dipole approximation of the numerical calculation and the basic theory of the method of combining different gold for gold and silver composite nanostructures silver extinction ratio, and refractive index sensitivity characteristics. The results show that the increase in the thickness of the nanoparticles will cause nanoparticles extinction peak wavelength blue shift. The extinction of the increase in the proportion of the gold material causes the nanoparticles of gold and silver composite structure peak wavelength red shift. Meanwhile, the results also show that the localized surface plasmon excitation intensity does not change when the thickness of the nanoparticles of gold and silver composite structure is greater than the mean free path of the free electron. Having more \The structure is sandwiched between two cubes of silver nanoparticles layer of Si02 Si02 However, the strong local electric field distribution main contribution into the mezzanine Obviously this part of the farm will lose the ability to response to changes in the external environment, the refractive index of the sensitivity naturally affected. To solve this problem, you can remove the sharp corners at the Si02 make the main contribution to the strong local electric field exposed to the external environment. Thus, this paper proposes a I type Ag/SiO2/Ag of composite structures, using the finite difference time domain method to study the extinction characteristics of the structure in different SiO2 layer thickness and refractive index sensitivity characteristics. The calculation results show that the ratio adjusting size larger position of the adjustment range of the resonance peak can be obtained by adjusting the layer thickness, to enhance the extinction efficiency of the nanoparticles (the maximum enhanced about 1.5 times), can make the local electric field becomes strong, and allows local electric field strength of the upper and lower levels are unevenly distributed. Than Ag/SiO2/Ag composite structure, the refractive index of the composite structure of the I-type Ag/SiO2/Ag the sensitivity increased 100nm/RIU.

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