本研究包含兩部分，第一部分為利用多元醇還原法合成不同尺寸分布之銀奈米立方體，以自組裝單分子層方式置放其於銀表面做為拉曼增顯基板，透過不同波長的拉曼激發光源分別檢測不同待測物(Rhodamine 6G、crystal violet 與 adenine)，了解改變銀奈米立方尺寸對於拉曼增顯效果差異。藉由紫外光/可見光光譜分析得知不同尺寸銀奈米立方體之表面電漿共振波長存在所對應特定激發光波長，搭配不同待測物之吸收波長存在所對應特定激發光波長，進而達到最大化拉曼增顯效應。
第二部分為利用模擬方式了解銀奈米立方體於銀表面於固定激發光波長下電場分布情形。由電場分布結果可瞭解，利用自組裝單分子層技術所得之拉曼增顯基板，主要增顯機制來自於銀奈米立方體與銀表面間所產生的強大感應電場。由於銀奈米立方體尺寸不同造成表面電漿共振波長差異，致使在固定激發光波長下產生不同的電場能量分布，顯示銀奈米立方體之尺寸具備選擇性以達到最大之電場能量分布情形。最後比較增顯基板之紫外光/可見光光譜與模擬計算表面電漿共振波長圖譜，確認兩者波長位置相符。
本研究提出銀奈米立方體存在所對應之特定波長，搭配待測物存在所對應之特定波長，可達到最大化拉曼增顯效應；透過模擬分析電場能量分布進一步探討電場增顯機制，歸納建議未來可先藉由模擬方式推測實驗製備之拉曼增顯基板的最適激發光源。

In this research, we experimentally and computationally study surface enhanced Raman scattering (SERS) substrates with different size of silver nanocubes (AgNCs) for the detection different analytes. Silver nanocubes (AgNCs) with different sizes are successfully prepared by a facile the polyol process with ethylene glycol as a solvent and a reducing agent. Robust SERS substrates with enormous hotspots can be fabricated by assembling AgNCs on the silver surface via 1,2-ethanedithiol monolayer as the spacer. The SERS efficiencies are further evaluated by using Rhodamine 6G (R6G), crystal violet (CV) and adenine as Raman analytes. It’s demonstrated that the intensities of SERS signals are related to the sizes of the AgNCs at respective excitation wavelengths. The experiment results of the size-dependent surface plasmon resonance properties of the AgNCs are compared with theoretical calculations. Through finite difference time-domain (FDTD) numerical simulation, we find that the electric field enhancements are sensitive to the sizes of the AgNCs.

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