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的激發脈衝以1+1 共振增強多光子游離技術將MNMA分子透過苯環端的S1 state游離至陽離子D1/D2 state，隨後陽離子D1/D2 state將緩解至陽離子D0 state，在陽離子緩解過程中，我們利用波長位於550～1500 nm之探測脈衝將陽離子激發至更高能態，使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。我們利用各波長下之最大離子損耗率並透過內插法得到超快時間解析離子光分解光譜，並在光譜中發現三個特徵鋒，分別為550～675 nm的譜帶、750 nm的譜帶及1250 nm的譜帶。我們以連續動力學模型擬合MNMA分子的離子損耗瞬時訊號並得到三個時間常數，時間常數τ1為0.08～0.2 ps、時間常數τ2為15～26 ps及時間常數τ3為370～475 ps。我們將時間常數τ1指認為MNMA陽離子D1/D2 state緩解至D0 state的電荷轉移過程，時間常數τ2及時間常數τ3指認為MNMA陽離子在D0 state構型緩解再平衡的過程。我們實驗所測得的MNMA超快時間解析離子光分解光譜中，550～675 nm的譜帶為陽離子D1/D2 state之吸收，750 nm的譜帶為剛緩解至陽離子D0 state初始構型之吸收，1250 nm的譜帶為陽離子D0 state較穩定構型之吸收。在較短延遲時間範圍內，550～675 nm譜帶及1250 nm譜帶隨著延遲時間增加而有互相消長之行為，此行為代表電荷轉移過程的發生，在較長延遲時間範圍內，750 nm的譜帶及1250 nm譜帶隨著延遲時間增加而有互相消長之行為，此行為代表構型緩解再平衡過程的發生。

In this thesis, we employed femtosecond pump-probe photoionization-photofragmentation spectroscopy in combination with time-of-flight mass spectrometry to observe ion-depletion transient signals for investigating the cation dynamics of MNMA (methyl[(1,2,3,4-tetrahydronaphthalen-2-yl)methyl]amine). We used pump pulse at 266 nm through 1+1 resonance-enhanced multiphoton ionization (REMPI) to locally ionize MNMA molecules via the phenyl group to reach the cation D1/D2 state. Subsequently, the D1/D2 state rapidly relaxed to the D0 state. During the relaxation process, we sent in probe pulses between 550~1500 nm to excite the cation to higher-energy states, leading to fragmentation of the cation and decreasing of the parent cation signal. We measured ion depletion transients by monitoring the cation signal as a function of the pump-probe delay time. We used maximum depletion yields at various wavelengths and obtained an ultrafast time-resolved ion photofragmentation spectrum of MNMA cation by means of interpolation. In this spectrum, we found three different absorption bands at 550–675 nm, 750 nm, and 1250 nm. We used a consecutive kinetic model to fit the ion depletion transients and obtained three time constants: τ1 of MNMA is about 0.08~0.2 ps, τ2 is about 15~26 ps, and τ3 is about 370~475 ps. We assigned τ1 to the charge transfer of MNMA cations from the D1/D2 state to the D0 state. We assigned τ2 and τ3 to the equilibrium process among conformers in the D0 state. The ultrafast time-resolved ion photofragmentation spectrum of MNMA exhibited three different bands. The 550~675 nm spectral band was due to the absorption of the D1/D2 state, the 750 nm band was due to the absorption of MNMA cations similar to the initial configuration of the D0 state, and the 1250 nm band was due to the absorption of the more stable configuration of the D0 state. In the short delay time scale, the 550~675 nm band decreases and the 1250 nm band increases with increasing delay time, reflecting the occurrence of charge transfer processes. In the longer delay time scales, the 750 nm band increases and the 1250 nm band decreases with increasing delay time, reflecting the occurrence of the equilibrium process among various stable conformers in the D0 state.

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