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

通过瞬态光栅方法研究宽时间范围内反应分子的动力学

基本信息

批准号：
06403007
负责人：
HIROTA Noboru
金额：
$ 11.78万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (A)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

项目摘要

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

将锁模激光泵浦的染料激光器的输出分成三路，其中两路通过取二次谐波产生亚皮秒紫外光脉冲。这两个脉冲激光在样品上交叉，产生激发分子的瞬时光栅(Tg)，剩余的光用作探测光。通过这种方法，我们构建了一个在亚皮秒范围内进行热重实验的系统。我们还利用皮秒激光泵浦的染料激光器的三次谐波，建立了一套用于皮秒到纳秒实验的热重分析系统。有了这些系统，我们现在可以在从毫秒到亚皮秒的非常广泛的时间范围内进行TG实验。利用这些装置进行了以下研究：(1)在皮秒范围内的研究；(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)我们成功地完成了d…由于温度的变化而产生的折射率变化所产生的光栅，是随着热量的释放而瞬时出现的。用这种光栅研究了Fe(III)在水中和2-羟基二苯甲酮在十二烷基硫酸钠胶束溶液中的快速动力学。(1.3)测定了不同溶剂密度下超临界CO_2中六甲苯/四氰基乙烯络合物的电子转移反应速率。(2)微秒级TG实验的新进展：(2.1)进一步研究了自由基的扩散，阐明了自由基扩散慢于母体分子的原因。(2.2)发展了一种测定光化学反应中的热变和反应体积变化的新方法，并将其应用于二苯基环丙烷的反应研究。(2.3)首次用热重方法研究了超临界液体中的输运性质和反应动力学。较少