週期性奈米金屬結構對拉曼散射訊號增強之研究

The Study of Periodical Metallic Nanostructures for Surface Enhanced Raman Scattering

許閔(Min Hsu)

指導教授 ： 李正中 ； 陳怡君

國立中央大學/理學院/光電科學研究所/碩士(2011年)

摘要

本論文研究主要使用有限時域差分法模擬計算在週期性金屬奈米結構下之表面電漿共振效應，並針對奈米球微影技術模擬其相關光學現象，不同的粒子形狀、大小和高度等參數都會對周期性金屬奈米結構所對應的共振現象有所影響。而此相關研究對許多方面的應用都相當有幫助，例如表面增強拉曼散射、單分子偵測技術以及其它像是太陽能電池效率提升等用途。
第一部分我們利用預測的奈米球微影術所形成之週期性奈米點狀陣列結構計算其消光截面積之物理量以了解所對應之表面電漿共振波長。模擬結果顯示，藉由變化奈米點狀陣列結構之材料、厚度、大小等皆會造成共振波長位置的移動，例如結構厚度增加或是基板折射率的減少，都會造成共振波長藍移的現象，而金屬銀相對於金在同樣條件之下，其共振波長位置皆小於金，藉此可做為製程前的事前評估。
第二部分為實際進行實驗，利用奈米球微影技術製作週期性奈米結構基板，並應用於量測表面增強拉曼散射現象之用途。實驗結果顯示，針對濃度為10-3M之R6G分子溶液可完成定性量測，並觀測到其表面增強拉曼散射之現象。

關鍵字

侷域表面電漿共振 ； 表面增強拉曼散射 ； 奈米球微影技術

並列摘要

In this study, we used finite-difference time-domain method to study the surface plasmon resonance effects of metallic periodical nanostructure. The simulation model was constructed based on the nanosphere lithography (NSL) process to calculate the optical properties. The size, shape, and thickness of the periodical metallic nanostructure were varied to find their influence on plasmonic effects. It would be useful if the optimum parameters are found, and they''re likely to have significant impact in several applications, such as surface enhanced Raman scattering (SERS), single-molecule spectroscopy, and efficiency enhancement of solar cells.
In the first part of this thesis, the periodical nanostructure is made by nanosphere lithography process which we forecast is investigated the corresponding LSPR wavelengths by extinction cross section. Simulation results show that the LSPR effects can be changed by controlling the size, thickness, and material of structure. For instant, the LSPR wavelengths blue shifted to the shorter wavelength as the thickness of the nanostructure increases, or the value of substrate index refraction decreases. And compare with the materials of Ag and Au in the same condition, the position of LSPR wavelengths in Ag is shorter than Au. These optical properties can made assessments before the process.
In the second part of this thesis, we experiment the NSL technology to fabricate periodical nanostructure as SERS active substrates. The results show we accomplish 10-3M R6G solution qualitative measurement based on these substrates, and observed the phenomenon of SERS.

並列關鍵字

localized surface plasmon resonance ； surface-enhanced Raman scattering ； Nanosphere lithography

參考文獻

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