本論文是建立合適於單分子螢光量測實驗的溫控樣品平台，並利用具有溫控功能之單分子螢光量測系統探討液晶系統的相變化。液晶是介於高度秩序的結晶固體與極端無秩序的液體這兩種極端的中間狀態。一方面，它保有液體般的流體性質；另一方面，它表現出類似結晶態固體般的部分秩序性。我們試著摻雜螢光分子於液晶中，透過溫控系統分別在固相、液晶相、液相中，觀察螢光分子的螢光表現，與週遭環境之關聯性及液晶的局部動態行為。
我們所建立的溫控樣品平台至少可工作於20oC至40o溫度間，樣品溫度控制穩定度可以達到0.1oC內。透過這系統分別觀察半導體量子點、DiI分子及Rhodamine B分子於5CB液晶中不同相狀態下的螢光表現。單一量子點在5CB固相中螢光強度及螢光生命期的結果與在PMMA下相似，呈現清楚的on-off blinking行為，且具有單一指數螢光生命期表現；而在液晶相及液相中則觀察到螢光強度呈現緩慢的變化，而螢光生命期呈現time-dependent anisotropy decays，這些說明量子點在液晶相及液相中轉動的趨勢。關於DiI以及Rhodamine B分子的觀測，樣品濃度則不侷限於單一分子之限制，但即使如此，在稀薄樣品中，藉著螢光強度起伏相干之關聯所得到的Fluorescence Correlation Spectroscopy (FCS)可以得到不同時間尺度的運動行為。其中，DiI在液晶中的螢光生命期結果具有不同的起始反應時間，推測是由於DiI在5CB中產生分子堆疊現象，造成不同狀態下螢光波長的改變，而APD對於不同的波長有不同的反應時間，因而造成觀測之結果有不同起始反應時間行為表現。此外，Rhodamine B於FCS結果中，則分別在ms時間尺度的線性擴散行為，

In this dissertation, we construct a temperature controlled sample stage that is compatible with high numerical aperture objective optical microscope, and perform single molecule experiments under the system. Mixing dilute fluorophore (CdSe/ZnS quantum dot, DiI, Rhodamine B) into the liquid crystal matrix (5CB), we monitor the fluorescence dynamics of the individual fluorophore at various temperature.
Different from the thermodynamic states of conventional materials, those specific class of materials which we called “liquid crystals” are attracted for their existence of unique liquid crystal phase, which exhibits a solid-state like higher orientation ordering, and a liquid-state like liquidity. Probe individual fluorophore allows us to monitor the nanometer length scale local structural and dynamic heterogeneity in the solid, liquid crystal and liquid phases.
The operating temperature of the platform covers more than 20 oC to 40 oC range with stability much better than 0.1 oC. Quantum dot in PMMA exhibits a clear on-off blinking behavior, and the single exponential fluorescence lifetime relaxation. While in the solid phase of the liquid crystal matrix, quantum dot exhibits similar behavior, which indicates the quantum dot is confined in the matrix. However, there exists slightly difference in decay lifetime. On the contrary, in the liquid crystalline phase as well as the liquid phase, quantum dot exhibits bi-exponential relaxation behavior. Besides a similar time scale relaxation dynamics, there exists additional fast decay behavior, which is from the feasible rotational rotation in the non-rigid matrix. In particular, the anisotropic decay dynamics in the liquid crystalline phase indicates the orientation preference of the liquid crystal molecules. Fluorescence Correlation Spectroscopy (FCS) provides the information of local dynamics of various time scales. FCS results exhibit an unclear transition that crossovers several decades in time scale, which indicates the highly heterogeneity of the liquid crystal.
The results of DiI exhibits different rising time in the fluorescence lifetime measurement, which implies the forming of aggregation due to the limited solubility of the DiI molecules in the liquid crystal matrix. Results of Rhodamine B exhibit a clear rotational diffusion dynamics at ~ microsecond scale and the corresponding translational diffusion dynamics at ~ mini-second scale. Moreover, the transition time scale of translational diffusion exhibits a temperature dependence. At higher temperature, it shifts to a shorter time scale.

第一章 簡 介 1
1.1 背 景 1
1.2 研究動機 2
第二章 原 理 3
2.1 螢光簡介 3
2.1.1 螢光現象 3
2.1.2 螢光表現 4
2.1.3 螢光相關光譜（FCS）偵測: 5
2.2 液晶簡介 9
2.2.1 液晶分類 9
2.2.2 液晶的物性 11
2.3 溫控系統 15
第三章 溫控樣品平台架設 18
3.1 樣品溫控系統 18
3.1.1 系統建立 18
3.1.2 樣品加熱平台系統 19
3.1.3 物鏡加熱系統 22
第四章 溫控系統實驗結果與討論 24
4.1 樣品溫控系統之量測 24
4.1.1 樣品加熱平台之樣品位置加熱時間紀錄 24
4.1.2 樣品加熱平台之樣品位置溫度量測 25
4.1.3 物鏡加熱系統於不同的設定溫度其物鏡溫度量測 27
4.1.4 樣品平台加熱系統與物鏡加熱系統連結之樣品基板溫度量測 28
4.2 溫控加熱系統實驗討論 30
第五章 單分子螢光實驗步驟及儀器簡介 31
5.1 單分子螢光實驗儀器架構 31
5.2 實驗步驟 32
第六章 螢光實驗結果與討論 34
第七章 結 論 43
參考資料 43

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