Multiplet

A resonance that exhibits (scalar) coupling to spin-1/2 nuclei appears as a multiplet, or appears to be split into many peaks. These patterns may be relatively simple (doublet, triplet, or quartet) if the coupling is straightforward, or more complex if it is the result of coupling to chemically or magnetically inequivalent nuclei. In simple patterns, the spacing between each peak, which is equal, is called the coupling constant and is given in units of Hz. It is more difficult to specify the coupling constant in the more complicated situations.