本論文主要呈現三個新的模型分子系統的合成以及其光學性質的探討。此三種新模型系統分別為含二氰基的吡嗪（pyrazine）及喹喔啉（quinoxaline）衍生物、二苯并印并吩嗪（dibenzoindenophenazine）衍生物以及具反轉中心的多芳香環共平面分子。在光學性質的探討方面，我們量測了吸收及放射光譜、螢光量子產率、螢光生命期，並以飛秒時域雷射進行雙光子激發螢光實驗，得出模型分子的雙光子吸收截面值，再以光功率依賴性實驗確認螢光強度與激發光功率的關係，證實模型分子是透過雙光子吸收機制產生螢光。我們歸納實驗結果並得到以下結論： (1) 二氰基取代基具有降低分子HOMO與LUMO的能隙、提升電荷轉移能力、增加雙光子吸收截面值、以及在極性溶劑中產生螢光淬滅等效果。 (2) 二苯并印并吩嗪衍生分子以Y形連接electron-donor可有較高的雙光子吸收截面值（~1800 GM），T形則具有較長螢光生命期（7.6 ns）。 (3) 具反轉中心的多芳香環共平面分子，我們發現其單光子吸收峰的兩倍波長處無雙光子吸收，而單光子無吸收處之兩倍波長卻具有窄而高的雙光子吸收峰（~1400 GM），展現雙光子吸收和單光子吸收之選擇定則相反的特性。 ;In this thesis, we present the synthesis and the characterization of optical properities of three novel molecular systems. The model compound system include the derivatives pyrazine/quinoxaline with dicyano group, dibenzoindenophenazine, and a polycyclic aromatic compound with centrosymmetry. For optical property characterization, we have measured the absorption and emission spectra, fluorescence quantum yield and lifetime. The nonlinear optical properties of two-photon absorption cross section were measured by two-photon excited fluorescence in the femtosecond domain. We also did the power dependence experiment to verify the two-photon absorption mechanism of model molecules. Our finding are summarized as follows: (1) The dicyano substituents could be introduced to decrease the HOMO-LUMO energy gap. It also enhances the ability of intramolecular charge transfer and two-photon activities. In addition, these moldel compounds showed fluorescence quenching in polar solvents. (2) The dibenzoindenophenazine derivatives exhibit stronger two-photon absorptivity It is found that the Y-shape model compound has the largest two-photon absorption cross section value (~1800 GM) while T-shape analogue possesses longer fluorescence lifetime (7.6 ns). (3) The centrosymmetric nature of the polycyclic aromatic compound (8) has led to the distinct spectral distribution pattern of its one-photon and two-photon absorption. In other words, the distribution of the one-photon accessible excited-states is dramatically different from that of two-photon accessible excited-states.
