Nuclei with I > ½, like for instance N, are characterized by an anisotropic distribution of the nuclear electric charge, which gives rise to an electric quadrupole moment of the nucleus, interacting with the electric field gradients present in a molecular system. This interaction, independent of the magnetic field, should be considered together with the interaction of the nuclear magnetic moment with the external magnetic field (Zeeman interaction), which, on the other hand, is field dependent. Both these interactions contribute to the energy of the 14 N states.