How can NMR spectra show the electric quadrupole moments of nuclei?

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magnetic resonance Figure 1: Precession of a magnetic dipole moment μ in the presence of a constant field H and a rotating field H′ (see text)

In nuclear magnetic resonance (NMR) spectroscopy, the presence of a nuclear electric quadrupole moment is revealed through the interaction between the nucleus and the electric fields present at the nuclear site.1

A nucleus with an electric quadrupole moment possesses a charge distribution that deviates from perfect sphericity. When such a nucleus is placed in an environment where an electric field gradient exists, the quadrupole moment interacts with that field. This interaction influences the energy levels of the nuclear spin states, which in turn affects the NMR spectrum. By analyzing these spectral features, researchers can gain detailed information regarding the microscopic distribution of electric charge surrounding the nucleus.21