Abstract: NMR spectra of samples in which free radical reactions are taking place may show strongly perturbed intensities for lines belonging to reaction products. This effect is called CIDNP. CIDNP has became an important method for mechanistic investigation of reactions involving short-lived radical intermediates.
In this paper the radical pair theory of CIDNP was qualitatively and quantitatively discussed. The field dependence of the CIDNP effect was analyzed. The triplet mechanism of CIDNP was briefly described and some applications of CIDNP to photochemistry were given.