2,6-二甲基苯胺及氘取代物之離子特性研究
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2009
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Abstract
我們應用高解析度共振雙光子游離與質量解析臨界游離光譜術(MATI)來探討2,6二甲基苯胺與2,6二甲基苯胺之氘取代物的分子特性，精準地量測游離能，並記錄這些分子的D0離子基態的振動光譜。
由實驗得知2,6-二甲基苯胺與2,6-二甲基苯胺-NHD、2,6-二甲基苯胺-ND2的游離能分別為59816 5 cm-1、 59796 5 cm-1 和59780 5 cm-1。
從光譜的分析中，可以證明在2,6-二甲基苯胺的共振二光子游離程序中，當分子由激態躍遷至第一電子激發態時，電子躍遷較傾向於電子雲附近，而由第一電子激發態躍遷至離子態時，主要是二甲基苯胺上氮原子未共用電子對，其中的一個電子被游離，形成了離子。並且與先前實驗室發表之數據作比較，提供最新的取代基特性與氘取代物對分子的游離能以及振動模式造成之影響，而量子化學ab initio及密度泛函數的理論計算亦支持實驗所觀察到的結果。
Two-color resonant two-photon mass analyzed threshold ionization (MATI) spectroscopy was used to record the threshold ion spectra of deuterium-substituted isotopomers of 2,6-dimethylaniline. The respective adiabatic ionization energies of 2,6-dimethylaniline, 2,6-dimethylaniline -NHD, and 2,6-dimethylaniline-ND2 were determined to be 59816, 59796, and 59780 cm-1 with an uncertainty of about 5 cm-1. Analyses on the shifts in the electronic transition and ionization energies prove that the S1 ← S0 transition mainly occurs around the aromatic ring whereas the transition from the neutral S1 to the cationic state corresponds to the removal of one of the lone-pair electrons of nitrogen. The present results provide the first experimental evidence for the site-specific electronic transition in 2,6-dimethylaniline as well as the isotope effects on the vibrations of the 2,6-dimethylaniline cation. These findings are well supported by ab initio and density functional calculations.
Two-color resonant two-photon mass analyzed threshold ionization (MATI) spectroscopy was used to record the threshold ion spectra of deuterium-substituted isotopomers of 2,6-dimethylaniline. The respective adiabatic ionization energies of 2,6-dimethylaniline, 2,6-dimethylaniline -NHD, and 2,6-dimethylaniline-ND2 were determined to be 59816, 59796, and 59780 cm-1 with an uncertainty of about 5 cm-1. Analyses on the shifts in the electronic transition and ionization energies prove that the S1 ← S0 transition mainly occurs around the aromatic ring whereas the transition from the neutral S1 to the cationic state corresponds to the removal of one of the lone-pair electrons of nitrogen. The present results provide the first experimental evidence for the site-specific electronic transition in 2,6-dimethylaniline as well as the isotope effects on the vibrations of the 2,6-dimethylaniline cation. These findings are well supported by ab initio and density functional calculations.
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二甲基苯胺, 氘取代物, 質量解析臨界游離光譜術, MATI, 2, 6-dimethylaniline