MAGNETIC FIELD EFFECT OF SPIN DYNAMICS IN THE RECOMBINATION PROCESS OF SHORT-LIVED ION-PAIRS INDUCED BY IRRADIATION

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The spin dynamics in recombination process of the short-lived ion-pairs induced in some kinds of fluorinated toluene by irradiation have been studied mainly in the current year. The magnetic field dependence of the yield of the singlet and triplet state in the recombination process also was discussed, Moreover, the hyperfine coupling constant of the radical anion of 2, 3, 4-trifluoro toluene was determined for the first time by the signal observed by optically detected electron spin resonance (ODESR).The samples used in this experiment were squalane solutions of penta-fluoro toluene, octa-fluoro toluene, 2,3,4-trifluoro toluene and alpha, alpha, aopha-trifluoro toluene in which included paterphenyl as a luminescent sensitizer.90 muCi^<90>Sr was used as the radiation source, ODESR spectrum was observed with the conventional X-band ESR spectrometer equipped a micro-wave amplifier.It is found that the luminescence yield for every sample depends on the concentration, temperature and magnetic field, respectively. The intensity of ODESR signal was found to be related to their dependences. The relation between them can be explained by the terms of the density of ion-pairs, the life-time of ion-pairs, the hyperfine coupling constant, spin-lattice relaxation time T_1 and spin-spin relaxation time T_2. In particular, the magnetic field dependence of the fluorescence yield can be explained qualititatively based on the calculation proposed by B.Brocklehurst. This suggests that the relation between the life-time of the ion-pairs and T_1 is important for the magnetic field dependence of the fluorescence yield.