在本篇論文中，我們利用飛秒激發-探測技術搭配光游離-光裂解機制觀察MNMA (methyl[(1,2,3,4-tetrahydronaphthalen-2-yl)methyl]amine)、MPPA (N-methyl -3-phenylpropan-1-amine)、MPEA (N-methylphenylethylamine)及MPMA (N-methyl benzylamine)陽離子激發態的緩解動態學過程。首先我們以波長266 nm的飛秒雷射將分子透過苯環端的局部S1 state以1 + 1共振增強多光子游離技術將苯環端局部游離，再以波長798 nm的飛秒雷射作為探測脈衝觀察陽離子的電子傳遞到苯環端及其他動態學行為。由於分子在中性基態時會有數類構型(例如：彎曲及展開構性)且會影響到電子供給端與接收端在空間中的直線距離(RPh---N)，為了釐清此距離對電荷轉移的影響，我們以碳橋含有六碳環結構的MNMA分子做為參考，六碳環的存在會使MNMA分子的構型相對較單純，而其他三種分子則會有數種穩定存在的構型，我們改變分子束振動冷卻效果讓各構型的佈居數分佈發生變化進而對瞬時訊號產生影響，並以理論計算找出各個分子在不同分子束條件下的構型分佈情形。我們以連續動力學模型擬合所有瞬時訊號，並得到2或3個時間常數(τi)。其中τ1我們認為是陽離子在D1 state的初始分子內振動能重新分配過程，τ2則為陽離子從D1 state緩解至D0 state的電荷轉移過程(τCT)，而τ3則指認為陽離子緩解至D0 state後的構型再平衡過程，經過理論計算發現若陽離子在D0 state時，有兩個以上較穩定的構型，那我們就可以觀察到此構型分佈的平衡過程。最後我們得出當RPh---N大於5.8 Å時，τCT約為15~16 ps；RPh---N縮短至4.5 Å時，τCT會變為4.2 ps；最後當RPh---N再縮短至3.7 Å時，τCT會加快至1.3~1.7 ps，此τCT隨RPh---N的變化概略符合指數衰減的趨勢。但是我們也發現有些數據並不完全符合上述的趨勢，這暗示我們RPh---N雖然會顯著的影響τCT，但似乎尚存在其他會影響τCT的重要因素。

We used femtosecond pump-probe photoionization-photofragmentation (fs-PIPF) spectroscopy to study ultrafast charge transfer (CT) dynamics in methyl[(1,2,3,4-tetrahydronaphthalen-2-yl)methyl]amine (MNMA), N-methyl-N-(3-phenylpropyl) amine (MPPA), N-methylphenylethylamine (MPEA), and N-methyl benzylamine (MPMA) cations. We used 1+1 resonance-enhanced multiphoton ionization to locally ionize their phenyl group via their S1 state and probed the subsequent relaxation dynamics in the cations by using a delayed femtosecond probe pulse that resulted in ion fragmentation. Because these molecules exist as different kinds of conformers at their neutral ground states, which can change the distance between amino group and phenyl group (RPh---N) that might affect charge transfer rate in the cations, therefore, we monitored the transients under different vibrational cooling conditions, which would change the population of neutral conformers. Based on the results of theoretical calculations, we obtained the relative energies and the populations among all neutral ground state conformers. Using a consecutive kinetic model to fit the ion depletion transients, we obtained two or three time constants (τi). We assigned τ1 to be the initial intermolecular vibrational energy redistribution process in the D1 state, τ2 the internal conversion from the D1 state to D0 state that is equivalent to a charge transfer process. τ3 was assigned to be the equilibrium process among conformers in the D0 state. If there are more than two stable conformers in the D0 state, we can observe equilibrium processes among these conformers. According to our experimental and theoretical results, when RPh---N are around 5.8~6.3 Å, 4.5 Å, and 3.7 Å, the τCT are about 15~16, 4.2, 1.3~1.7 ps, respectively. Most of the results are consistent with an exponential decay relationship between RPh---N and τCT. However, not all data point agrees with above relationship, implying that RPh---N is probably not the only factor that affects τCT.

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