A Study of Structure of Unstable reaction Intermediates by Pulsed Electron-Nuclear Double Resonance

1.脉冲电子-核双共振仪的建立一台自制的脉冲电子顺磁共振装置被改装用于流体溶液中的光化学反应的Endor实验。(1)脉冲源谐振器的设计与制造设计制造了一种微波谐振器，可以同时用射频、微波和激光脉冲辐照样品。(2)脉冲测序仪的改进设计并搭建了一套激光与脉冲EPR同步系统。激光脉冲和微波脉冲之间的抖动小于3 ns。(3)外加磁场的稳定利用调频检测质子核磁共振信号的高斯计。高斯密计可以用来稳定电磁铁。2.电子顺磁共振测量软件的改进计算机系统与数字信号采样器之间的数据传输速度提高了五到十倍。3.数据分析软件在我们的光谱分析软件上实现了一种线性预测分析的快速算法。4.光致电子转移的瞬时自由基的观察我尝试观察到一种锌对苯二酚光致电子转移反应的中间产物--阳离子自由基。我尝试了两种方法：(1)直接法(直接测量Endor)和(2)解耦方法，遗憾的是，我无法通过现有的仪器和方法观察到Endor(或解耦)效应。为了观察瞬变自由基的结束或，我必须改进以下几点：(1)照射在样品上的射频功率必须更大，(2)为了改善射频和静态磁场之间的正交性，射频线圈必须更坚固。

1. Construction of a Pulsed Electron-Nuclear Double Resonance Instrument a home build pulsed EPR instrument was modified for ENDOR experiments on a photo-chemical reaction in fluid solution. (1) Design and Construction of a Resonator for Pulsed-END OR A microwave resonator was designed and constructed by which I could irradiate a sample with RF, microwave and laser pulse simultaneously. (2) Improveing Pulse Sequencer I designed and constructed a system which synchronized a raser and a pulsed EPR apparatus. A jitter between a laser pulse and a microwave pulse was less than 3 ns. (3) Stabilization of an External Magnetic Field A Gaussmeter which utilized FM-detection of a proton NMR signal was constructed. The Gaussmeter can be used to stabilize an electromagnet. 2. Modification of A Software for EPR Measurements A speed of data transfer between a computer system and a digital signal sampler was improved by a factor of five to ten. 3. Data Analysis Software I implemented a fast algorithm of linear prediction analysis on our spectral analysis software. 4. Observation of A Transient Radical of Photo-Induced Electron Transfer I tried to observe a ZnTPP cation radical which was an intermediate of a photo-induced electron transfer reaction between ZnTPP and benzoquinone. I tried two methods : (1) Direct method (direct measurement of ENDOR) and (2) Decoupling method.Unfortunately I could not observe ENDOR (or decoupling) effect by means of present instrumentation and methods. To observe END OR of a transient radical, I must improve following points : (1) RF power which is irradiated on a sample, must be larger, (2) to improve orthogonality between a RF and a static magnetic field, a RF coil must be more rigid.