The interaction between the spin magnetic moment of an unpaired electron and the nuclear
spin magnetic moments resulting in the splitting of the α (spin up) and β (spin down)
energy levels in an external magnetic field and, thus, in the multiplet pattern of
the
ESR spectra of radical-like species and transition metal compounds. Two main contributions
to the hyperfine
coupling are usually considered,
Fermi contact and dipolar interactions. The contact interaction is
isotropic and related to the unpaired
spin density at the
nucleus,
.
The dipolar interaction is anisotropic, and related to
,
where
is the distance between the atom holding the unpaired electron and the
nucleus with non-zero spin.
Source:
Cite as:
IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by
A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997).
XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic,
J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8.
https://doi.org/10.1351/goldbook.
