This applet demonstrates the primary effects of scalar coupling. When Dn/J between two spins is not large (e.g. < 100) the spins are strongly coupled.

Strong coupling influences both the transition intensities and the observed splittings, often making spectral interpretation more difficult. Below, larger Dn should produce more symmetric spectra. Here, all spins have I=1/2. Unlike J, Dn increases with B_o so that strong coupling effects are diminished in high field spectrometers. Note that the transitions associated with the third spin (X) are not observed in the plot because they are assumed far away from the displayed frequency range (i.e. weakly coupled).