臺灣博碩士論文加值系統

拉曼散射乃光子與化學分子間之非彈性散射現象。表面增強拉曼散射大大地強化分子的微弱拉曼訊號，因而成為敏銳的分子鑑定工具，廣泛地應用在化學及生物領域。如此極度的增強效果乃由於入射電磁場與金屬區域性表面電漿子相互耦合，於金屬奈米結構周圍形成強烈近場分佈。
實驗中製備各種二維金奈米結構之SERS活性基板，包含金奈米薄膜、奈米孔隙金膜及奈米粒子-薄膜複合結構，並運用機械刮劃方式製作微米等級之擰屈狀金箔堆積。本研究以R6G為探測分子來進行SERS增強效應之探討。
厚度為2 nm至10 nm之金薄膜中，5 nm金膜的半連續薄膜結構形成豐富的熱點位置，獲得最強之R6G 分子SERS訊號，平均AEF達1.72 × 10^4。此外，由10至20 nm之奈米粒子與5 nm薄膜所組成的複合結構中，粒子分布密度約0.5/μm^2，可進一步提升十餘倍的強化效果，平均AEF達1.96 × 10^5。
實驗中製備10 nm至50 nm之奈米孔隙金膜，密集分佈的孔洞其尺寸約10 nm至250 nm。30 nm奈米孔隙金膜結構可獲得較佳的增強效果，AEF約為1.15 × 10^4。另外，奈米粒子與30 nm孔隙薄膜構成的複合結構其SERS效應僅獲得些微提升。
利用原子力顯微鏡與矽探針於20 nm至60 nm的金膜上進行機械刮劃，於刮痕末端自然形成微米等級之擰曲狀金箔堆積，此金屬堆積便形成良好的SERS熱點位置。於20 nm金膜上進行10 μm至700 μm不同長度之刮劃可獲得10^4 - 10^6之AEF值。此外，平行刮痕凹槽方向之偏振電場可進一步優化SERS效應，訊號強度提升二至三倍，並於40 nm金膜上之500 μm刮劃得最高AEF值，達3.80 × 10^5。

Raman scattering is an inelastic scattering of photons by chemical molecules. Surface-enhanced Raman scattering (SERS) greatly enhances the normally weak Raman signal and thus becomes a sensitive technique for identification of analyte molecules in chemical or biological analysis. The gigantic signal enhancement results from the intense optical field intensity produced around the metal nanostructures on a SERS-active substrate as the incident electromagnetic waves couple to the localized surface plasmons of the metal.
In this study, a number of SERS-active substrates with two-dimensional gold nanostructures including plain gold films, nanoporous gold films, and hybrid structures of gold nanoparticles (NPs) on film were prepared. A mechanical scratching method was also employed to create microscale piles of gold sheets. Rhodamine 6G (R6G) was used as the target molecule to evaluate the SERS effect.
Plain gold films with thicknesses ranging between 2 and 10 nm were prepared and the strongest SERS signal was obtained from the 5 nm thick film with an average analytical enhancement factor (AEF) of 1.72 × 10^4. It is believed that the semicontinuous framework of the 5 nm film provides abundant ‘hot spots’ and gives the strongest SERS signal. Furthermore, a hybrid film of NPs (10 to 20 nm in size and area density of 0.5/μm2) on the 5 nm thick gold film gives 10 times improvement and the AEF reaches around 1.96 × 10^5.
Nanoporous gold films with thicknesses ranging between 10 and 40 nm were prepared, and the sizes of these densely distributed pores range between 10 and 250 nm. An average AEF of 1.15 × 10^4 has been obtained for the 30 nm thick nanoporous film. A hybrid film of NPs on the 30 nm nanoporous film was also prepared, but the SERS effect was improved only marginally.
A commercial AFM and a silicon probe were employed to perform mechanical scratching on gold films with thicknesses of 20 to 60 nm. A microscale pile of rolled gold sheets was created at the end of a scratching and became an excellent SERS-active site. By using various scratching distances of 100 to 700 μm on 20 nm plain film, AEFs of 10^4 - 10^6 were obtained. In addition, the SERS signal is stronger when the incident light polarization is parallel to the scratching direction. A highest AEF of 3.80 × 10^5 has been obtained on a 40 nm thick gold film with a scratching of 500 μm.

誌謝 I
摘要 II
Abstract IV
圖目錄 IX
表目錄 XII
第一章 緒論
1.1 拉曼散射 2
1.2 表面增強拉曼散射 5
1.3 研究動機 6
第二章 文獻回顧
2.1 拉曼散射 8
2.1.1 拉曼散射理論 8
2.1.2 拉曼光譜及其特性 9
2.2 SERS增強機制 11
2.2.1 電磁增強機制 11
2.2.2 化學增強機制 15
2.3 距離與偏振效應 17
2.4 SERS發展與應用 20
第三章 實驗方法
3.1 實驗儀器 23
3.1.1 電子束蒸鍍系統 23
3.1.2 拉曼光譜儀 24
3.1.3 原子力顯微鏡 26
3.1.4 掃描式電子顯微鏡 26
3.2 實驗藥劑 28
3.3 SERS活性基板製備 30
3.3.1 金奈米薄膜製備 30
3.3.2 奈米孔隙金膜製備 30
3.3.3 奈米粒子-薄膜複合結構製備 31
3.3.4 AFM刮劃金屬堆積 31
3.4 拉曼光譜量測 33
3.5 SERS光譜量測 34
第四章 結果與討論
4.1 R6G拉曼光譜 36
4.2 金奈米薄膜SERS光譜 37
4.2.1 薄膜厚度 37
4.2.2 薄膜沉積速率 39
4.3 奈米孔隙金膜SERS光譜 40
4.4 奈米粒子-薄膜複合結構SERS光譜 41
4.5 AFM刮劃金屬堆積SERS光譜 43
4.5.1 刮劃長度 43
4.5.2 刮劃金膜厚度 46
4.5.3 偏振效應 47
4.5.4 人工刮劃 50
4.6 數據比較 52
第五章 結論 54
參考文獻 57

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