- 學位論文
芳香分子電子激發態及離子光譜研究
Vibronic and cation state spectroscopic investigations of aromatic molecules
摘要
利用雙色共振雙光子質量解析臨界游離光譜技術應用於1-cyanonaphthalebe的陽離子震動光譜；結構異構物o-fluorophenylacetylene, m-fluorophenylacetylene, p-fluorophenylacetylene, p-fluorophenylacetylene水合物；2,4-difluorophenol的旋轉異構物；4-chloro-3-fluorophenol的同位素異構物、旋轉異構物；4-chloro-3-fluorophenol水合物。本實驗精確測量上述分子的躍遷能和絕熱游離能，並使用ab initio及密度泛函理論來做理論計算預測分子結構、振動、躍遷能及游離能以強化本實驗的結果。此外，本文亦針對上述實驗結果和類似分子做比較。 由於2,4-difluorophenol分子內氫鍵的影響，實驗結果顯示只觀察到cis構型的異構物。然而，在4-chloro-3-fluorophenol的實驗中，同時觀察到此分子不同的旋轉異構物及同位素異構。質量解析臨界游離光譜顯示這些分子大部分的振動型態都為平面振動。而且，上述兩分子的OH官能基位相對於振動型態的影響很小。比較2,4-difluorophenol、4-chloro-3-fluorophenol以及cis-2-fluorophenol, 3-fluorophenol, 4-fluorophenol and 4-chlorophenol，發現氟和氯這些取代基造成的躍遷能變化量具有可以加成的特性。這些分子振動頻率的變化和分子本身的特性、振動模式、官能基的種類和相對位置都有關係。
並列摘要
Abstract Two-color resonant two-photon mass-analyzed threshold ionization spectroscopy was applied to study the vibrationally resolved cation spectra of the of 1-cyanonaphthalene; structural isomers of o-fluorophenylacetylene, m-fluorophenylacetylene, p-fluorophenylacetylene, and p-fluorophenylacetylene water complex; selected rotamers of 2,4-difluorophenol, selected rotamers and isotopologus of 4-chloro-3-fluorophenol and 4-chloro-3-fluorophenol water complexes. The S1 ← S0 electronic transition energy and the adiabatic ionization energies of these molecular species has been precisely measured along with this we performed ab initio and density functional theory calculations to predict the molecular structure, vibration, and electronic transition and ionization energies to strengthen our experimental findings. Moreover we compare these experimental finding with respective similar molecular species. The present 2,4-difluorophenol experimental results show that only cis form involved in the photo-excitation and ionization processes, due to presences of intramolecular hydrogen bonding. While in case of 4-chloro-3-fluorophenol, there are two stable rotamers and isotopologus (35Cl and 37Cl) coexisting in the sample. Analysis on the MATI spectra shows that most of the active cation vibrations of these molecular species result from in-plane ring motions. Moreover, different orientations of the two OH groups have little effect on these vibrations. Comparing the data of cis-2,4-difluorophenol and 4-chloro-3-fluorophenol with those of phenol, cis-2-fluorophenol, 3-fluorophenol, 4-fluorophenol and 4-chlorophenol one can learn that there may have an additivity rule associated with the energy shift resulting from the additional fluorine and chlorine substitution. Frequency shifts in these molecules somewhat depends on the nature, vibrational pattern, location and relative orientation of the substitutents.