本論文利用飛秒泵浦-探測光游離-光裂解(Femtosecond Pump-Probe Photoionization-Photofragmentation)光譜術結合質譜偵測技術研究2-phenylethyl-N,N-dimethylamine (PENNA), N-methylphenethylamine (MPEA) 及 2-phenylethylamine (PEA)陽離子的電荷轉移反應及離子基態構型緩解動力學。本實驗利用1+1 REMPI技術使S0 state分子先吸收一個泵浦雷射光子(λpump = 265.9 nm)到達S1 state再吸收第二個泵浦雷射光子以游離化PENNA等分子，接著導入探測雷射(λprobe = 800 nm)將PENNA+等離子打到更高能的激發態後碎裂，我們藉由調控不同的泵浦-探測脈衝延遲時間擷取離子訊號，得到離子損耗瞬時光譜，並以連續反應動力學模型進行適解，進而獲取PENNA+等離子態之動力學資訊。 PENNA+、MPEA+和PEA+的損耗瞬時光譜皆分別得到三個時間常數，在和無電荷轉移的分子—PEAL+離子之瞬時訊號適解結果比較後，我們認為PENNA+、MPEA+及PEA+這些陽離子內的電子轉移過程約為0.2、0.3及0.1 ps，和Schlag團隊2005年研究結果的80 fs略有差異。我們也對PENNA等分子進行理論計算及結構優化，並根據所得之離子基態穩定構型推斷PENNA+、MPEA+、PEA+及PEAL+電子轉移後皆會發生兩段構型緩解過程，最後變為離子基態最穩定之間扭式構型，這兩段構型緩解過程約為數個至數十皮秒時間尺度。

We study the ultrafast charge transfer (CT) dynamics in the cations of 2-phenylethyl-N,N-dimethylamine (PENNA), N-methylphenethylamine (MPEA) and their non-methylated counterpart, 2-phenylethylamine (PEA) after photoionization using the femtosecond pump-probe photoionization-photofragmentation (fs-PIPF) spectroscopy. Neutral PENNA, MPEA, PEA seeded in a He free jet are photoionized by femtosecond 1+1 resonance-enhanced multiphoton ionization via their S1 state, and the subsequent dynamics occurring in the cations is probed by delayed pulses that result in ion fragmentation. Using a kinetics model to fit our transients, we obtained three time constants from the PENNA+, MPEA+ and PEA+ ion depletion transients. We ascribed the sub-picoseconds time constants of PENNA+ (0.2 ps), MPEA+ (0.3 ps) and PEA+ (0.1 ps) to the CT dynamics by comparing them with a non-CT system 2-phenylethyl alcohol cation. Our results are quite different from those reported by the Schlag group in 2005. Besides, we also find some much shower components with time constants of few to few tens of picoseconds. These slower components were attributed to conformational relaxation of cations after CT.

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