Radio Induced 12C/13C Magnetic Isotope Effect

The separation of carbon isotopes ¹²C and ¹³C induced by magnetic electron–nuclear interaction in radical pairs is increased by selective microwave pumping at the frequency of EPR transitions in ¹³C-containing radicals; the pumping accelerates the triplet–singlet conversion of ¹³C radical pairs and therefore increases the nuclear spin selectivity of chemical reactions; this new effect has been called the radio induced magnetic isotope effect (RIMIE).