Nuclear magnetic resonance detected nuclear resonance of transient radicals

Nuclear resonances in transient radicals produced in liquids by pulse radiolysis have been detected by using NMR of their reaction products. The NMR intensities are affected by application of rf corresponding to nuclear resonances of the radical intermediates. NMR-detected nuclear resonance (NMR-NR) spectra for several chemical systems are presented. Information from these spectra about relative populations of the radical magnetic energy levels is explained with the radical pair theory of chemically induced magnetic polarization, both electron (CIDEP) and nuclear (CIDNP). For some systems, weak lines in the NMR-NR spectra have been assigned as due to double quantum transitions between energy levels differing by two in nuclear spin quantum number