External Magnetic Field Effects on Dynamic Behavior of Excited Molecules

本项目的第一个目的是澄清磁场对受激分子动力学行为影响研究中的一些尚未解决的问题。二是寻找新的磁场效应，扩大磁场效应的适用性。首先，我们借助瞬态吸收和CIDEP技术研究了磁场和磁同位素对胶束中自由基对重组速率的影响机制。从观察到的CIDEP信号的衰减率和类镧离子的内部磁场效应来看，弛豫机制适用于上述效应。用纳秒和皮秒染料激光器研究了气态<CS_2>荧光的磁猝灭机理。从观察到的磁场对荧光激发光谱和荧光衰减曲线的影响来看，发现一些分子内弛豫过程是磁猝灭的起源。为了第二个目的，我们研究了磁场对具有比F重原子的杂有机自由基反应的影响，并在s中心自由基的反应中发现了这种影响。此外，我们还构建了一个研究低压气体中磁场对燃烧反应的影响的装置，发现了不同的磁场对NO的B态和OH、ch的A态形成过程的影响。我们还得到了一些意想不到的结果：(1)羰基光还原中环己二烯基型和苯基型自由基的形成；(2)在胶束中观察到一些CIDEP光谱的相交替效应。这些结果引起了国际社会的关注。

The first purpose of the present project is to clarify some unresolved Problems in the studies of the magnetic field effects on dynamic behavior of excited molecules. The second one is to find new magnetic field effects in order to extend applicability of the effect.For the first purpose, we studied the mechanism of the magnetic field and magnetic isotope effects on the recombination rates of radical pairs in micelles with the aids of transient absorption and CIDEP techniques. From the observed decay rates of the CIDEP signals and the internal magnetic field effects of lanthanoid ions, the relaxation mechanism was shown to be applicable to the above-mentioned effects. The mechanism of the magnetic quenching of the fluorescence of gaseous <CS_2> was also studied with nanosecond and picosecond dye lasers. From the observed magnetic field effects on the fluorescence excitation spectra and fluorescence decay curves, some intra-molecular relaxation processes were found to be the origin of the magnetic quenching.For the second purpose, we investigated magnetic field effects in the reactions of hetero-organic radicals having heavier atoms than F and found the effect in a reaction of an S-centerd radical. Furthermore, we constructed an apparatus for studying the magnetic field effects on combustion reactions in low-pressure gasses and found various magnetic field effects on the formation processes of the B state of NO and the A states of OH and CH.We have also obtained some unexpected results: (1) formation of cyclo-hexadinenyl type and benzyl type radicals in photoreduction of carbonyls and (2) alternating phase effects in some CIDEP spectra observed in micelles. These results attracted international attention.