4-氯-3-氟苯胺與4-氯-3-氟苯甲醚之第一電子激發態暨離子態振動光譜研究
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2014
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我們利用共振雙光子游離與質量解析臨界游離光譜術來紀錄4-氯-3-氟苯胺(4C3FA)及4-氯-3-氟苯甲醚(4C3FAN)的第一電子激發態暨離子態光譜，用以探討分子的特性。以目前的儀器解析度極限，35Cl與37Cl具有相同的第一電子躍遷能(E1)和絕熱游離能(IE)，4C3FA分別為33 242及63 868 cm-1，順-4-氯-3-氟苯甲醚為35 295及67 279 cm-1，而反-4-氯-3-氟苯甲醚則為35 412及67 548 cm-1。依據光譜分析結果顯示大多數之譜峰為苯環平面運動及取代基之彎曲運動。
將4C3FA的數據與4-氯苯胺、3 -氟苯胺和苯胺比較，我們發現在第一電子躍遷能和絕熱游離能存在添加規則(additivity rule)，這意味著取代基氯、氟、胺基的作用力是微弱的。除此之外，我們也利用從頭計算法(ab initio)及密度泛函理論與實驗結果對照，提供合理的解釋數據。
而本實驗所測得4C3FA與4C3FAN的第一電子激發態振動光譜和離子態光譜可以用作指紋分子鑑定。
We applied the resonant two-photon ionization and mass-analyzed threshold ionization techniques to record the vibronic and cation spectra of 4-chloro-3-fluoroaniline and 4-chloro-3-fluoroanisole to investigate their molecular properties. The excitation energy of the S1 ← S0 transition (E1) and the adiabatic ionization energy (IE) of 4-chloro-3-fluoroaniline are found to be 33 242 and 63 868 cm-1, respectively. Comparing these data with those of 4-chloroaniline, 3-fluoroaniline, and aniline, we find an additivity rule associated with the E1 and IE. This implies that the interaction among the Cl, F, and NH2 substituents is weak. The vibronic featues of 4-chloro-3-fluoroanisole are found to build on 35 295 and 35 412 cm-1 corresponding to the band origins of S1 ← S0 electronic transition (E1) for cis and trans rotamers. The adiabatic ionization energies (IEs) for these two species are found to be 67 279 and 67 548 cm-1, respectively. These newly recorded vibronic and cation spectra can be used as fingerprints for molecular identification.
We applied the resonant two-photon ionization and mass-analyzed threshold ionization techniques to record the vibronic and cation spectra of 4-chloro-3-fluoroaniline and 4-chloro-3-fluoroanisole to investigate their molecular properties. The excitation energy of the S1 ← S0 transition (E1) and the adiabatic ionization energy (IE) of 4-chloro-3-fluoroaniline are found to be 33 242 and 63 868 cm-1, respectively. Comparing these data with those of 4-chloroaniline, 3-fluoroaniline, and aniline, we find an additivity rule associated with the E1 and IE. This implies that the interaction among the Cl, F, and NH2 substituents is weak. The vibronic featues of 4-chloro-3-fluoroanisole are found to build on 35 295 and 35 412 cm-1 corresponding to the band origins of S1 ← S0 electronic transition (E1) for cis and trans rotamers. The adiabatic ionization energies (IEs) for these two species are found to be 67 279 and 67 548 cm-1, respectively. These newly recorded vibronic and cation spectra can be used as fingerprints for molecular identification.
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共振雙光子游離, 臨界游離, 第一電子激發態振動光譜, 離子態光譜, 4-氯-3-氟苯胺, 4-氯-3-氟苯甲醚, resonant two-photon ionization, threshold ionization, vibronic spectrum, cation spectrum, 4-chloro-3-fluoroaniline, 4-chloro–3-fluoroanisole