Construction and Application of a Multi-Function Laser Photolysis ESR

为了将ESR谱仪与各种光谱测量设备相结合，制成多功能的激光光解ESR谱仪，进行了以下工作。(1)介绍了一种可变波长脉冲TAG激光系统，用于在可见光至紫外光范围内进行不同波长的激光光解。(2)对ESR共振腔进行了改造，使其能同时进行CIDEP和激光光度测量。(3)本文尝试用ESR共振腔同时测量ESR、共振吸收和荧光。(4)对ESR谱仪进行了改进，使之能在自旋子能级间产生微波跃迁，从而实现ESR的光学检测。1）用ESR和瞬态吸收研究光化学反应的初始过程：详细研究了异丙醇对氮杂芳烃分子的夺氢反应产生的自由基的CIDEP。所观察到的CIDEP信号强烈依赖于浓度，激发光强度和延迟时间，表明涉及几种不同的CIDEP机制。得出的结论是，在相对高的浓度下观察到的净发射偏振可能是由于自由基-三重态对机制（RTPM）。将观测信号的时间分布与基于可能的反应和弛豫方案的理论预测进行了比较。2）光化学反应和CIDEP的CW和FT时间分辨ESR研究：详细研究了各种分子被2-丙醇基猝灭的速率和CIDEP三重态机理的磁场依赖性，获得了许多新的信息。

In order to make a multi functional laser photolysis ESR spectrometer by combining an ESR spectrometer with various equipments for spectroscopic measurements the followings were made.(1) A variable wavelength pulsed-TAG laser system was introduced to perform laser photolysis at various wavelengths in the visible to UV region. (2) An ESR cavity was modified to do simultaneous measurements of CIDEP and laser photlysis. (3) Simultaneous measurements of ESR,reansient absorption and fluorescence were tried using an ESR cavity. (4) The ESR spectrometer was modified to do optical detection of ESR by inducing microwave transitions among spin-sublevels. After checking the performance of the spectrometer system, the follwoing studies were made.1) Studies of the initial processes of photochemical reactions by ESR and transient absorption : We have made a detailed investigation on the CIDEP of redicals produced by hyrogen abstraction reactions of azaaromatic molecules by 2-propanol. The observed CIDEP signals are strongly dependent on the concentration, the excitation light intensity and the delay time, showing that several different CIDEP mechanisms are involved. It was concluded that the net emissive polarization observed at relatively high concentrations are likely due to the radical-triplet pair mechanism (RTPM). The time profiles of the observed signals were comparaed with the theoretical predictions made on the basis of possible reaction and relaxation schemes. The effect of the T-T annihilation on the CIDEP signal rise was also clarified.2) CW and FT time-resoved ESR studies of photochemical reactions and CIDEP : Detailed investigations on the quenching rates of various molecules by 2-propanolyl radical and the magnetic field dependence of the triplet mechanisms of CIDEP were made and much new information was obtained.