表面增強拉曼光譜(SERS)近期在檢測領域上佔有非常重要的地位，拉曼散射是一種強而有力的分析技術，他能提供分子結構上的資訊並應用於快速的篩檢或是分子蹤跡的檢測上，但是在實際應用上，用於測量拉曼強度的基板也面臨到許多問題，例如整個基板的各個位置測量強度不均又或是製作基板時的良率不高，導致在追蹤待測分子時的不便。因此，如何發展出一個簡單的檢測樣品前處理技術並應用於實際的分子追蹤上已經成了研究的顯學。而利用貴金屬奈米顆粒來增強拉曼光譜訊號可以說是最常見的方法。

在此研究中，我們提出了全新的實驗設計。我們利用多形狀的奈米金顆粒結合銀薄膜來達到一個強大的電場增幅效果，同時可以提升整個基板的增強因子以及量測拉曼訊號時的均勻度，此法也稱作Nanoparticle on mirror法。此基板是利用物理蒸鍍系統在矽基板上鍍上一層銀薄膜，再將基板泡入硫醇中使得硫醇可以貼附在銀薄膜上並充當間隔物，最後用旋塗法滴上自己開發的可以在水溶液中合成奈米金顆粒的方法--水熱法及晶種法，用以合成八面體、菱形十二面體和立方體的奈米金顆粒，此外，由於三種奈米金顆粒有著不同數量的尖端邊緣、尺寸，以及基板浸泡硫醇的時間控制、旋塗法的轉速，這些參數都在這個實驗設計裡，所需要在其中找到一組最優化的組合搭配，所以藉由科技工業上常用的統計的方法-田口方法(Taguchi method)，我們得以設計一個適當的實驗製程，並在眾多實驗參數裡得出一個最佳化的組合。另外，這個實驗的另個突破在於基板上的多形狀奈米金顆粒由於緊密地彼此靠近著，又由於奈米顆粒與銀薄膜間只隔著3-5奈米的硫醇，因此能夠達到強烈的尖端放電效果外，整個基板也因為擁有良好的金奈米顆粒的分佈，導致在基板上的各個位置量測到的拉曼訊號均差異不大，

從分析拉曼光譜的訊號中得知，多樣染料的拉曼峰值以及檢測限都能達到相當好的水準。並且藉由基板穩定度的測試中得知，此設計下的基板能夠抗氧化並維持能夠激活表面增強拉曼光譜的特性長達4個月，證明了此設計可以在利用簡單的方法以及較低的成本中達到追蹤低濃度化學分子的特性。

因此證實此研究可以嚴謹地同時控制奈米顆粒的形狀和排列下，大幅的提升在檢測待測物的能力，相信此基板能夠有潛力應用於實際的生化快篩檢測上。

Surface enhanced raman spectroscopy（SERS）is a powerful analytical technique that reveals structural information of molecules to provide fast screening and detection applications. In this research, sensitive SERS substrates with hotspots on a large scale from massive nanogaps can be fabricated by assembling polyhedral gold nanoparticles on the massed Ag mirror via 1,2-ethanedithiol monolayer as ultra-thin spacer. 

Preparation of different diameter of nanoparticles with excellent morphology control is necessary for demonstrations of their shape-dependent optical properties. Theoretically, SERS activity is related to the large localized field enhancement such as the presence of sharp tips and is thus critically shape-dependent for nanoparticles. With different morphologies of gold nanoparticles, we can not only confirm our substrate is more stable than traditional noble metal nanoparticles coated substrate but also make a denser close packed structure with sharp corners. Furthermore, we have proved that self-assembly structure combine with nanoparticle on mirror(NPOM) configuration can increase SERS signal dramatically. 

In our work, we applied seed-mediated synthesis method for the preparation of gold nanoparticles. It's the first synthesis process done in aqueous solution. The combination of using cetyltrimethylammonium chloride (CTAC) surfactant and a small amount of NaBr to control the bromide concentration in the growth solution was important to the formation of nanoparticles. Variation in the volume of ascorbic acid added to the growth solution enabled the fine control of nanocrystal morphology. Next, by spin coating we can fabricate a close packed gold nanoparticles monolayer on a dielectric layer that deposited on silver mirror. Due to the existence of ultra-thin dielectric spacer, it can prevent the directly touch of two metallic surfaces, which prevails the strong plasmonic interaction at the nanogap between two metal surfaces. By this design, we were able to conclude size and shape effect of noble metal nanoparticles on SERS. 

摘要
Abstract
Content
Acknowledge
List of Figures
List of Tables
Chapter 1 Introduction………………………………………………………………P.1
Chapter 2 Literature review
2.1 Surface-enhanced Raman spectroscopy(SERS) ………………….…………P.3
2.1.1 Raman technique…………………………………………………...…...P.3
2.1.2 Surface-enhanced Raman spectroscopy………………………...………P.5
2.1.3 Plasmonic paper………………………………………………….……P.10
2.2 Evolution of the SERS active elements and distribution…………..………P.12
2.2.1 Engineered nanomaterials (ENMs) of SERS…………………….……P.12
2.2.2 Polyhedral gold nanoparticles synthesis………………………………P.17
2.2.3 Langmuir Blodgett method………………………………...………….P.22
2.2.4 Nanoparticles on mirror(NPOM)…………………… ……….……….P.26
2.3 Taguchi method…………………………………………………………….P.28
Chapter 3 Design of experiment
3.1 Gold nanoparticles Synthesis………………………………………………P.31
3.1.1 Seed mediated Synthesis………………………………………………P.33
3.1.2 Hydrothermal Synthesis…………………………………………….…P.37
3.2 Sample fabrication…………………………………………………………P.39
3.2.1 Nanoparticles on mirror(NPOM)………………………………...……P.39
3.2.2 Preparation of Dithiol………………………………………….………P.40
3.2.3 Spin coating ………………………………………………………..…P.42
3.3 Taguchi method……………………………………………………….……P.43
3.4 Spotting technique…………………………………………………….……P.47
3.5 Raman measurement…………………………………………………….....P.49
Chapter 4
4.1 Benefit of NPOM structure……………………………………...…………P.50
4.1.1 Polyhedral gold nanoparticles…………………………………………P.50
4.1.2 Surface property of substrate…………………………………….……P.58
4.2 Taguchi L9 OAs and Raman measurement…………………………..……P.62
4.3 Enhancement factor…………………………………………………...……P.70
4.4 Uniformity test………………………………………………………..……P.72
4.5 CST simulation……………………………………………………….……P.74
4.6 XPS spectra………………………………………………………...………P.77
4.7 Detection limit………………………………………………….…...……P.79
Chapter 5 Conclusion………………………………………………….………P.82
References…………………………………………………………………….……P.84
Future work………………………………………………………………………...P.89

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