Photoinduced electron-transfer and magnetic-field effects on the decay rates of photogenerated biradicals in a phenothiazine-C₆₀ linked compound with six methylene groups: Temperature dependence

Photoinduced electron-transfer reactions and magnetic-field effects (MFEs) on the decay of photogenerated biradical in a phenothiazine-C₆₀ linked compound with six methylene groups were examined in benzonitrile at various temperatures (283-343 K). The decay rate constants of the biradicals were dramatically decreased in the lower magnetic fields (0-0.2 T) and increased in the higher magnetic fields (0.2-1.0 T). These reverse phenomena in the MFEs were more clearly observed with the increase of temperature and are explained by the contribution of spin-lattice relaxation mechanism due to anisotropic Zeeman interaction. The temperature dependence on the MFEs supports the above mechanism.