CROSS-RELAXATION AND CROSS-CORRELATION MECHANISMS LEADING TO SPIN POLARIZATION

The photolysis of acetone with various hydrogen donors and of 3-hydrox y-3-methyl-2-butanone involves formation of propan-2-olyl radicals sho wing both electron and nuclear spin polarizations. The presence of ele ctron polarization in radicals leads to additional CIDNP appearing in reaction products. The transfer of polarization from electron spins to nuclear ones can occur by cross-relaxation and cross-correlation mech anisms. Experimentally, these mechanisms manifest themselves by format ion of net CIDNP in symmetrical radical pairs as well as by unusual ki netic behaviour of multiplet CIDNP.