Dynamics of Photodissociation and Rearrangement of Chemical Bonds in Solution

L.蒽和1，4-二卤代苯异二聚体在溶液中的光解离当异二聚体在溶液中被激发时，从异二聚体的激发单重态产生蒽的激发单重态和二卤代苯的基态。用皮秒激光光谱仪测量了异二聚体自身荧光和生成蒽的荧光随时间的变化以及溶液中时间分辨的瞬态吸收光谱，发现在77 K时玻璃基质中的异激基缔合物激发下，蒽的荧光光谱比游离蒽的荧光光谱红移约10 nm，这表明在低温基质中蒽和二卤代苯之间可能保留了一种特殊的分子间构象。室温下，在粘性溶剂顺式十氢萘中检测到蒽的荧光动力学位移。四苯肼及其衍生物在溶液中的光解离用皮秒时间分辨光谱证实了四苯肼类化合物在荧光态下发生了N-N键的缓慢断裂。提出了从激发单重态（荧光态）到较低解离态的预解离机制。

l. Photodissociation of Heterodimers of Anthracene and 1, 4-Dihalobebzens in SolutionWhen a heterodimer is excited in solution, a excited singlet state of anthracene and a ground state of dihalobenzene are produced from the excited singlet state of the heterodimer. We have measured the time-dependence of the fluorescence of heterodimer itself and produced anthracene as well as the time-resolved transient absorption spectra in solution by means of a picosecond laser spectroscopy.The fluorescence spectrum of anthracene observed by the excitation of heteroexcimer in glass matrix at 77K is shifted to the red about 10nm compared to that of free anthracene, which indicate that a special intermolecular conformation between anthracene and dihalobenzene may be preserved in the low temperature matrix. Dynamical shifts of anthracene fluorescence were detected at room temperature in viscous solvent, cis-decalin.2. Photodissociation of Tetraphenylhydrazine and Its Derivatives in SolutionThe slow N-N bond rupture occurring in the fluorescence state of tetraarylhydrazines has been confirmed by a picosecond time-resolved spectroscopy. The predissociation mechanism from the excited singlet (fluorescent) state to the lower lying dissociative state was proposed.