Studies of the dynamics of reactive molecules by the transient grating method over a wide time range

用锁模YAG激光器泵浦染料激光器，将其输出分成三路，利用其中两路输出的光进行二次谐波处理，产生亚皮秒紫外光脉冲。这两个脉冲激光在样品处交叉以产生激发分子的瞬态光栅（TG），并且剩余的光用作探测光。通过这种方式，我们已经构建了一个系统，在亚皮秒范围内进行TG实验。我们还建立了一个TG系统的皮科到纳秒的实验使用的染料激光的三次谐波泵浦的皮秒YAG激光。有了这些系统，我们现在可以在很宽的时间范围内做TG实验，从毫微微秒到亚皮秒。使用这些设置进行了以下研究。(1)皮秒范围内的研究：（1.1）阐明了具有非常有效的非辐射过程的分子，如硝基苯及其衍生物和9，10-二氮杂菲的激发态动力学。(1.2)我们成功地在D ...更多信息 检测由于温度变化而引起的折射率变化所产生的光栅，该温度变化随着热的释放而瞬时出现。利用这种光栅研究了Fe（III）在水溶液和2-羟基二苯甲酮在SDS胶束溶液中的快速动力学。(1.3)本文测定了六氰基乙烯/四氰基乙烯络合物在超临界CO_2中不同溶剂密度下的电子转移反应速率。并将计算结果与理论预测进行了比较。(2)TG实验在毫秒到微秒范围内的新进展：（2.1）对自由基扩散作了进一步的研究，阐明了自由基扩散比母体分子慢的原因。(2.2)提出了一种测定光化学反应焓变和反应体积变化的新方法，并应用于二苯基环丙烷反应的研究。(2.3)首次采用热重法研究了超临界流体中的输运性质和反应动力学。少

The output of a dye laser pumped by a mode-locked YAG laser was divided into three, two of which were utilized to produce subpico second UV pulses by taking second the harmonics. These two pulsed-laser lights were crossed at the sample to produce a transient grating (TG) of excited molecules, and the remaining light was used as a probe light. In this way we have constructed a system to perform TG experiments in the subpico second range. We have also constructed a TG system for pico to nano second experiments using the third harmonics of a dye laser pumped by a pico second YAG laser. With these systems we are now equipped to do TG experiments over a very wide range of time from mili to subpico second. The following studies were made using these setups.(1) Studies in the picosecond range ; (1.1) Excited state dynamics of the molecules with very efficient nonradiative processes such as nitrobenzene and its derivatives and 9,10-diazaphenanthrene were clarified. (1.2) We have succeeded in d … More etecting the grating produced by the change in the refractive indecex due to the temperature change which appears instantaneously with the release of heat. Fast dynamics of Fe (III) in water and 2-hydroxybenzophenone in a SDS micellar solution were in vestigated by using this type of grating. (1.3) Rates of the electron transfer reaction in the hexamethylbenzene/tetracyanoethylen complex in supercritical CO_2 were determined at different solvent densities. The results were compared with the theoretical prediction.(2) New developments in the TG experiments in the mili to microsecond region : (2.1) Further studies on the radical diffusion were made to clarify the reason why radicals diffuse more slowly compared with parent molecules. (2.2) A new method to determine changes in enthalpy and reaction volume in a photochemical reaction was developed and applied to study the reaction of diphenylcyclopropane. (2.3) The TG method was used for the first time to study transport properties and reaction dynamics in a supercritical liquid. Less