Magnetic field effects on end product yields observed for photochemistry involving biradical intermediates

Magnetic field effects upon product yields are detectable for photoredox reactions of the chain molecules (4-nitrophenoxyl)-(methylene spacer)- (reductant) when the intersystem crossing rate between the singlet and triplet biradicals depends upon the magnetic field and the escape process involving the biradical intermediates and the starting species is relatively efficient. The magnitude of the magnetic field effects can be determined by the competition between the spin-lattice relaxation and the bimolecular escape process.