Quadrupole splitting

Quadrupole splitting refers to the interaction of electric quadrupole moments in nuclei or atoms in the presence of an electric field gradient. It is an important concept in nuclear magnetic resonance (NMR) and Mössbauer spectroscopy, among other spectroscopy techniques. In essence, when a nucleus with a non-spherical charge distribution (i.e., a quadrupole moment) is placed in an electric field gradient, it experiences an energy shift depending on the orientation of the nucleus relative to the electric field.