【作者】 潘洋；

【导师】 俞书勤；

【作者基本信息】 中国科学技术大学 ， 化学物理， 2006， 博士

【摘要】 时间分辨的激光闪光光解装置是为了在室温下鉴别光化学体系中存在的活泼中间体而形成的一种技术，已经被广泛地应用于各个领域。通过瞬态吸收光谱、激发态或自由基浓度等参量随时间的变化所提供的信息，便可以了解到光化学反应中间体的特征和动态特性。本文的工作主要是利用我室自行搭建的纳秒级激光闪光光解装置，并结合稳态吸收光谱、荧光(磷光)发射光谱和量子化学计算，研究了一些体系的光诱导电子转移反应。具体工作分以下四个部分： 1．研究了1，2-萘醌(NQ)和1，2-萘醌-4-磺酸钠(NQS)被355nm激光脉冲辐照后在乙腈(苯)溶剂中的瞬态吸收光谱和动力学参数。得到了不同酯肪醇、苯酚、酯肪胺、芳香胺猝灭NQ(NQS)激发三重态的猝灭动力学常数和部分瞬态吸收光谱，确定并归属了反应所涉及的主要过程为激光诱导的电子、质子转移反应机理。热力学结果也证实了胺类化合物猝灭~3NQ~*(~3NQS~*)的反应机理是光诱导的电子转移过程。运用DFT方法进行量子化学计算研究，得到了NQ、NQS和部分芳香胺的标准氧化还原电势、气相电离能、电子亲和势和苯胺上N原子的电荷密度分布。 作为光敏化剂，NQS比NQ有更高的反应活性和较大的猝灭速率常数，量化计算结果证实了这一点。两种敏化剂的溶剂效应非常显著，由于激发态从极性溶剂中的~3(π，π)~*构型变成非极性溶剂中的~3(n，π)~*构型，所以~3NQ~*(~3NQS~*)在苯中的反应活性要比在乙腈中的反应活性强，猝灭速率常数更大。此外，我们还讨论了苯胺衍生物猝灭~3NQ~*(~3NQS~*)反应的k_q和与Hammett取代常数、量化计算得到的苯胺衍生物氧化还原电势与N原子上电荷密度分布的关系，给出了合理的解释。 2．首次得到了2，3-二甲基喹喔啉和2，3，6，7-四甲基喹喔啉在乙腈溶剂中的瞬态吸收光谱、激发态动力学常数、激发三重态能量和标准氧化电势。 研究了2，3-二甲基喹喔啉、2，3，6，7-四甲基喹喔啉、2，3-二甲基萘和N，N，N’，N’-四甲基联苯胺四种光敏化剂和若干环状、链状缺电子烯烃的猝灭反应，得到了相更多还原

【Abstract】 Time-resolved laser flash photolysis is a new technique used to investigate the transient species of photochemistry systems at room temperature and has been applied in different research fields. The properties and dynamic characteristics of transients in photochemical processes could be obtained via transient absorption spectra and the change of transients’ concentration accompanied with the change of time. In this work, we mainly used home-made laser flash photolysis combined with steady Uv-vis absorption spectrum, fluorescence (phosphorescence) spectrum and quantum calculation to investigate some photo-induced electron transfer reactions. Detailed works are divided into four parts:1. Transient absorption spectra and corresponding dynamic parameters of triplets NQ and NQS in acetonitrile (benzene) were studied. Rate constants of ~3NQ~* (~3NQS~*) quenched by some aliphatic alcohols, phenols, aliphatic amines and aromatic amines were obtained. Photo-induced proton/electron transfer mechanisms were deduced. In addition, photo-induced electron transfer mechanism was testified by thermodynamic results. Standard redox potentials, gas phase ionization/affinity potentials and charge density distributions of some reagents were calculated by DFT method.As sensitizers, NQS is more active than NQ. It was approved by quantum calculation results. All the quenching rate constants measured in benzene are higher than those measured in acetonitrile. The increased reactivities of sensitizers in benzene can be explained by a conversion of excited state configuration of NQ (NQS) from ~3(π,π)~* to ~3(n,π)~3 . Furthermore, the relations between k_q and Hammett constants, redox potentials and charge density distributions calculated by DFT method were also discussed.2. Transient absorption spectra, dynamic constants, excited states energies and standard oxidation potentials of 2,3-dimethylquinoxaline (DMQ) and 2,3,6,7-tetramethylquinoxaline (TMQ) were obtained for the first time.The quenching reactions between DMQ, TMQ, 2,3-dimethylnaphthene (DMN),更多还原