EFFECTS OF HIGH MAGNETIC-FIELD ON ORGANIC-REACTIONS

Effects of high magnetic field (<14 T) on the primary process of organic photochemical reactions and related phenomena are reviewed. With increasing a magnetic field, lifetimes of tripler radical pairs in micellar solution and triplet biradicals in homogeneous solution increase significantly, reach their maximum values at ca. 2 T, and then decrease gradually up to 14 T. These results are interpreted in terms of the radical pair mechanism. The effects at low field are attributable to the reduction of spin transitions due to the isotropic and anisotropic hyperfine interaction. The inversion of the lifetime is attributable to the enhancement of spin relaxation induced by the anisotropic g-value.