Basic measurements of partial orders in solution

用飞秒时间分辨光谱法测定了反式二苯乙烯或联苯与四氯化碳之间的双分子化学反应动力学。所观察到的动力学可以用扩散控制反应的理论很好地解释。这一结果表明，分子在溶液中的平移运动可以很好地描述为几皮秒时间间隔后的扩散运动。研究了光激发诱导2-氨基吡啶/乙酸配合物双质子转移反应的机理。皮秒时间分辨光谱的实验结果表明，这种双质子转移是一个逐步进行的机制。对于这个反应，保持2-氨基吡啶和乙酸之间的分子复合物至少几皮秒是至关重要的。在己烷、辛烷和癸烷三种不同溶剂中，测定了反式二苯乙烯的反式异构化速率和第一激发单重态（S_1）的拉曼带形状的温度依赖性。根据实验结果，讨论了异构化反应速率与溶媒相互作用的关系。动态极化模型假设溶质-溶剂相互作用的振幅、持续时间和频率决定了反应速率和拉曼带形状，成功地解释了实验结果。溶解在SDS胶束疏水核中的反式二苯乙烯被光激发电离。皮秒时间分辨CARS实验表明，生成的阳离子径向在20ps内到达胶束和散装水之间的外部亲水性界面。然而，与阳离子径向同时生成的电子到达散装水需要1到2ps。

Kinetics of bimolecular chemical reactions between trans-stilbene or biphenyl and carbon tetrachloride have been measured with femtosecond time-resolved spectroscopic methods. The observed kinetics are well explained by theories of diffusion-controlled reactions. This result suggests that the translational motion of molecules in solution is described well as diffusion motion after a few picosecond time interval.Mechanism of a double proton transfer reaction induced by photoexcitation of the 2-aminopyridin / acetic acid complex has been examined. Experimental results from picosecond time-resolved spectroscopy show that this double proton transfer proceeds with a stepwise mechanism. It is crucial to keep the molecular complex between 2-aminopyridine and acetic acid for at least a few picoseconds for this reaction.Temperature dependence of the trans-cis isomerization rate as well as the shape of the Raman bands of the first excited singlet (S_1) state of trans-stilbene have been measured in three different solvents, hexane, octane, and decane. The relation between the isomerization reaction rate and the solute-solvent interaction is discussed based on the experimental results. The dynamic polarization model, which postulates that the amplitude, duration, and frequency of the solute-solvent interaction determine both the reaction rate and the Raman band shape, explains the experimental results successfully.Trans-stilbene solubilized in the hydrophobic core of the SDS micelle is ionized by photoexcitation. From the picosecond time-resolved CARS experiments, it has been suggested strongly that the generated cation radial reaches the outer hydrophilic interface between the micelle and the bulk water within 20 ps. It has been also suggested, however, that it takes 1 to 2 ps for the electron generated simultaneously with the cation radial to reach the bulk water.