External Magnetic Field Effects on Dynamic Behavior of Excited Molecules

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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.