This is one of the major information sources in NMR spectra. In proteins, for example, the signals of H N , H alpha , aromatic and aliphatic protons can be distinguished by their chemical shift. Additionally the chemical shift contains information about protein secondary structure. This splitting is caused by scalar coupling between the protons. The coupling is transmitted via chemical bonds.
Scalar coupling leads to a transfer of magnetization between nuclei.
This is the most important mechanism which is used in NMR spectroscopy for magnetization transfer apart from the nuclear Overhauser effect. Vicinal couplings depend on the torsion angle between the coupling protons. Therefore, it is possible to derive parts of the molecular geometry from the knowledge of coupling constants.