在本篇論文中，我們利用飛秒激發-探測光游離光裂解結合飛行時間質譜技 術產生離子損耗瞬時訊號來研究 MPEA (N-methylphenylethylamine)及 MNMA (methyl[(1,2,3,4-tetrahydronaphthalen-2-yl)methyl]amine)的陽離子動態學。我們利 用 266 nm 的激發脈衝將分子透過苯環端局部 S1 state，以 1+1 共振增強多光子游 離技術將苯環端局部游離形成最主要的陽離子D1/D2 state，而陽離子D1/D2 state 應會經內轉換緩解至 D0 state。在母陽離子緩解過程中，我們利用 600~1500 nm 探測脈衝將陽離子激發至更高能態，使母陽離子裂解產生離子碎片而造成母陽離 子訊號的損耗，並利用飛行時間質譜儀隨著激發與探測脈衝間的延遲時間測得離 子損耗瞬時訊號，以研究陽離子緩解的動力學過程。我們利用連續動力學模型擬 合不同探測波長所測得離子損耗瞬時訊號可得三個不同時間尺度的時間常數， MPEA 及 MNMA 時間常數 τ1 皆為 0.3~0.6 ps，時間常數 τ2 分別為 2.1~3.4 ps 及 16~21 ps，時間常數 τ3 分別為 90 ps 及 375 ps 左右。我們認為 τ1 是陽離子在 初始能態的分子內振動能再分配過程，τ2 為陽離子 D1/D2 state 經內轉換緩解至 D0 state 的電荷轉移過程，τ3 應為陽離子 D0 state 構型緩解再平衡的過程。我們實 驗所測得的 MPEA 超快時間解析離子光分解光譜為一中心位於 1100 nm 附近隨 延遲時間變化不太明顯的譜帶，我們推測這應該是陽離子 D0 及 D1/D2 state 的吸 收譜帶非常相似，導致吸收譜帶重疊使光分解光譜隨延遲時間變化不太明顯。 MNMA 超快時間解析離子光分解光譜中有兩個時間行為截然不同的主要譜帶， 我們推測位於 1200 nm 附近隨延遲時間下降的譜帶，是由陽離子 D1/D2 state 的吸 收所造成的，而位於 750 nm 附近隨延遲時間上升的譜帶，是由陽離子 D0 state 的吸收所造成的，此兩種物種之間的消長情形恰巧反映了 MNMA 陽離子由 D1/D2 state 內轉換至 D0 state 的電荷轉移過程。

We employed femtosecond pump-probe photoionization-photofragmentation spectroscopy in combination with time-of-flight mass spectrometry to study ultrafast charge transfer (CT) dynamics in N-methylphenylethyl amine (MPEA) and methyl[(1,2,3,4- tetrahydronaphthalen-2-yl)methyl] amine (MNMA) cations. These molecules are ionized in molecular beam by femtosecond pump pulses at 266 nm through 1+1 resonance-enhanced multiphoton ionization via their phenyl-group S1 state to reach the cation D1/D2 states in which the positive charge is largely localized in the phenyl group. The cation D1/D2 states subsequently relax to the D0 ground state, in which the positive charge is more localized in the amine group. To probe the relaxation dynamics in the cations, we used probe laser pulses with wavelengths ranging between 600 and 1500 nm to excite the evolving cationic system to higher excited states that undergo fragmentation, resulting in the loss of the parent cation signal. We measured ion depletion transient by monitoring the parent ion signal as a function of the pump vs. probe delay time. Using a consecutive kinetic model to fit the ion depletion transients, we obtained three time constants. τ1 of MPEA and MNMA are both about 0.3~0.6 ps, τ2 are about 2.1~3.4 ps and 16~21 ps, and τ3 are about 90 ps and 375 ps, respectively. We assigned τ1 to the initial intramolecular vibrational energy redistribution occurring in the D1/D2 state, τ2 to the internal conversion from the D1/D2 state to D0 state, which corresponds to a CT process. τ3 was assigned to the equilibrium process among conformers in the D0 state. The ultrafast time-resolved ion photofragmentation spectrum of MPEA cation exhibits a maximum at about 1100 nm and does not change significantly with delay time. The reason is probably that the absorption spectra of the cation D0 and D1/D2 states happens to be very similar, causing their absorption bands to overlap. The ultrafast time-resolved ion photofragmentation spectra of MNMA cation exhibits two main bands with different time behaviors. We assigned the 1200 nm band, which decreases with the delay time, to the absorption of the cation D1/D2 state. The other band, which locates at about 750 nm and rises with the delay time, was ascribed to the absorption of the cation D0 state. The decay and rise of the two bands reflect the CT process from the D1/D2 state to the D0 state.

摘要.................................................................................................................... I
ABSTRACT ........................................................................................................ II
目錄....................................................................................................................IV
第1章 緒論.......................................................................................................... 1
1.1 引文............................................................................................................ 1
1.2 文獻回顧.................................................................................................... 3
1.3 研究動機.................................................................................................... 8
第2章 實驗系統與技術....................................................................................... 10
2.1 基本實驗方法............................................................................................ 10
2.2 激發-探測脈衝雷射-共振增強多光子游離技術 .......................................... 12
2.2.1 激發-探測光激發-光游離 .................................................................... 13
2.2.2 激發-探測光游離-光裂解 .................................................................... 13
2.3 超快飛秒脈衝雷射系統.............................................................................. 15
2.3.1 振盪器系統........................................................................................... 16
2.3.2 脈衝能量放大器................................................................................... 22
2.4 波長調變儀................................................................................................ 30
2.4.1 非線性光學倍頻產生器......................................................................... 30
2.4.2 波長調變器:TOPAS................................................................................31
2.5 分子束系統................................................................................................ 34
2.5.1 超音速分子束........................................................................................ 35
2.5.2 分子束系統進樣裝置............................................................................. 39
2.5.3 分子束系統架設.................................................................................... 39
2.6 飛行時間質譜儀.......................................................................................... 42
2.7 實驗光路設計.............................................................................................. 45
2.8 訊號擷取系統.............................................................................................. 47
2.9 儀器響應函數.............................................................................................. 49
2.10 藥品來源.................................................................................................... 50
第3章 實驗結果與討論.......................................................................................... 51
3.1 MPEA 及 MNMA 分子的質譜........................................................................ 51
3.2 激發-探測光游離-光裂解的實驗條件 ........................................................... 53
3.2.1 激發雷射脈衝波長之選擇........................................................................ 53
3.2.2 激發與探測雷射脈衝能量比例對離子瞬時訊號之影響............................. 54
3.2.3 MNMA 陽離子損耗訊號驗證....................................................................58
3.3 離子損耗率與雷射脈衝之依存性................................................................... 60
3.3.1 離子損耗率之計算................................................................................... 60
3.3.2 離子損耗率與雷射脈衝能量之依存性....................................................... 61
3.3.3 超快時間解析離子光分解光譜之實驗條件................................................ 63
3.4 MPEA 超快時間解析離子光分解光譜及其離子損耗瞬時訊號 ..........................65
3.4.1 MPEA 超快時間解析離子光分解光譜 ........................................................65
3.4.2 MPEA 的離子損耗瞬時訊號及動力學模型之擬合 ......................................69
3.5 MNMA 超快時間解析離子光分解光譜及其離子損耗瞬時訊號..........................77
3.5.1 MNMA 超快時間解析離子光分解光譜........................................................77
3.5.2 MNMA 的離子損耗瞬時訊號及動力學模型之擬合......................................86
第 4 章 結果討論與分析...........................................................................................93
4.1 理論計算方法................................................................................................. 93
4.2 MPEA 陽離子電荷轉移動態學 ........................................................................95
4.2.1 MPEA 中性基態分子 ................................................................................ 95
4.2.2 MPEA 陽離子 D0 state ............................................................................ 97
4.2.3 綜合討論.................................................................................................. 99
4.3 MNMA 陽離子電荷轉移動態學......................................................................103
4.3.1 MNMA 中性基態分子...............................................................................103
4.3.2 MNMA 陽離子 D0 state ......................................................................... 105
4.3.3 綜合討論..................................................................................................107
第 5 章 結論............................................................................................................111
參考文獻................................................................................................................ 114

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