MECHANISM OF THE MAGNETIC-FIELD EFFECTS ON THE DECAY-RATE OF CHAIN-LINKED BIRADICALS

From the temperature dependence of the lifetime in a magnetic field (0.6 T), the decay rate of triplet biradicals, generated from the end-to-end photoreaction of xanthone-xanthene and benzophenone-diphenylamine bifunctional chain molecules, is shown to be controlled by the spin-relaxation process. The relaxation is induced by the fluctuating local field (1.2-1.8 mT), which is caused by the rotational motion of the component radicals. The origin of the field is mainly attributable to the anisotropic electron-nuclear dipolar interaction.