以共振二光子游離與質量解析臨界游離光譜術研究2-氟化萘分子之特性

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2010

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  本實驗利用雙色共振雙光子游離光譜術以及質量解析臨界游離光譜術來探討2-氟化萘在第一電子激發態和離子基態的分子特性,所得到的資訊包括從基態到第一電子激發態躍遷能量、游離能以及在第一電子激發態和離子態的振動光譜。這些振動光譜數據就如分子指紋一樣,可用來當作鑑定個別分子的依據。光譜分析的結果顯示出第一電子躍遷能為31803 ± 2 cm-1和絕熱游離能為66771 ± 5 cm-1。在光譜上所看到大部分的振動模式都和芳香環上的平面運動有關。比較本實驗所得到的2-氟化萘和文獻上萘的光譜數據可以幫助我們了解氟的取代基效應在萘上對電子躍遷和游離過程及分子振動的影響。另外我們也利用初始計算法及密度泛函數理論計算,來幫助進行分子光譜標定工作。
The two-color resonant two-photon ionization and mass analyzed threshold ionization spectroscopic techniques have been used to probe the molecular properties of 2-fluoronaphthalene (2FN). The obtained experimental data include the precise transition energy from the ground state to the first electronically excited state and the adiabatic ionization energy (IE) as well as the active vibrational spectra in the first electronically excited S1 and cationic ground D0 states. These new vibrationally resolved spectra can be used as fingerprints for molecular identification. Analysis of the obtained vibronic and cation spectra reveals that the origin of the electronic transition (E1) and the adiabatic IE of 2FN are 31803 ± 2 cm-1 and 66771 ± 5 cm-1, respectively. Most of the active vibrations of 2-fluoronaphthalene in the S1 and D0 states are related to in-plane vibrations of the aromatic ring. Comparing the experimental data of 2FN with those of naphthalene helps us learn the fluorine substitution affects on the electronic excitation and ionization processes as well as molecular vibration. We have also performed the ab initio and density functional calculations which help us in spectral assignment and support our experimental findings.

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質量解析臨界游離光譜術, 2-氟化萘, Mass-analyzed threshold ionization spectroscoopy, 2-fluoronaphthalene

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