Effect of an external magnetic field on the yield of radicals during the photoreduction of xanthene dyes in viscous media

Abstract

1. The application of an external magnetic field (H=0.18 T) leads to an increase of 10–150% in the escape of the radicals of xanthene dyes from the cage in a viscous solvent. 2. In erythrosine and ethyleosin, which contain heavy atoms, the magnetic effects (with η/T=3.3 cP/K) are smaller than in the case of fluorescein. This is due to the appearance of spin-orbital interaction in the radicals of the pair; the internal heavy atom effect appears in viscous media (η/T ≃ cP/K). 3. The presence of an external heavy atom leads to a decrease of the magnetic effect during the photoreduction of fluorescein and erythrosine. The external heavy atom effect appears in the region of “moderate” fluidities (1 ≳η/T ≳ 7 cP/K, [KI]=0.1 M). This effect does not appear with large η/T values on account of the transition to the diffusion-controlled region.