Coupling/decoupling

Couplings, or interactions, between nuclei can be either homonuclear (such as 1H-1H) or heteronuclear (such as 13C-1H). In either case, they cause splitting or broadening of the resonances in the spectrum, complicating interpretation. Irradiation, at an appropriate power level, at the frequency of a particular nuclide or resonance, is called decoupling. The interaction is thus removed, leading to a simpler spectrum.