New development in the studies of short-lived paramagnetic species by time-resolved ESR

本研究的目的是进一步扩展我们的时间分辨ESR工作，并寻求新的发展。新的发展有两个方向。一个是开发新的方法，另一个是使新的应用程序有趣的系统。在第一个区域，我们尝试了CIDEP-ENDOR和延迟瞬变章动技术。我们已经完成了初步实验，但需要进一步的调查，以评估这些技术的全部潜力。在第二个方面，我们获得了以下结果：1）短寿命三重态的研究a）分子内氢键分子我们研究了水杨酸甲酯及其相关分子在混合单晶中的三重态性质。将所得结果与UHF MO计算的结果进行比较。用时间分辨ESR研究了苯并恶唑和苯并噻唑在不同溶剂中的三重态，以阐明它们的三重态性质.B）吡啶衍生物：从ESR研究中阐明了4-氰基吡啶三重态的性质，并结合磷光研究和从头计算的结果.三重态为3 npi ^* 和3 pipi ^* 的混合态，结构畸变很大。c）C_6和C_6的三重态<70>：时间分辨ESR研究表明，这些分子的三重态具有显著的结构和动力学性质。2）短寿命自由基的研究我们研究了苯偶酰在不同溶剂中的CIDEP，特别是极化机制和在低温下CIDEP信号初始缓慢上升的过程。

The purpose of this research is to extend our time-resolved ESR work further and to seek new developments. There are two directions for new developments. One is to develop new methodology and the other is to make new applications to interesting systems. in the first area we have tried CIDEP-ENDOR and delayed transient nutation techniques. We have completed preliminary experiments, but further investigations are needed to evaluate the full potential of these techniques. In the second area we have obtained the following results.1) Studies of short-lived triplet statesa) Intramolecularly hydrogen@bonded molecules ; We have investigated the triplet properties of methylsalicvlate and related molecules in mixed single crystals. The obtained results were examined in comparison with the result of an UHF MO calculation. Time-resolved ESR studies were made on the triplet states of benzoxazole and bezothiazole in various solvents to clarify their triplet properties.b) Pyridine derivatives ; The nature of the triplet state of 4-cyanopyridine was clarified from a n ESR study together with the results of phosphorescence studies and an ab initio calculation. It was found that the triplet state is of mixed 3npi^* and 3pipi^* character with a very distorted structure.c) Triplet states of C_6 and C_<70> ; A time-resolved ESR study revealed remarkable structural and dynamic properties of the triplet states of these molecules. Detailed studies are being made at present.2) Studies of short-lived radicals ; We have studied CIDEP of benzil in various solvents, particularly the polarization mechanisms and the processes responsible for producing the initial slow rise of the, CIDEP signals at low temperatures.