Nuclear Hyperfine Interaction

Abstract

If the interaction of an electron with a magnetic field were the only effect operative, then all ESR spectra would consist of one line. The only useful information to be garnered from these spectra would be the g factor. The ESR technique would thus provide rather limited information. Fortunately there are other interactions which can produce spectra rich in line components. For the present, the discussion will be restricted to molecules containing one unpaired electron (S = 1/2), although much of the following will apply equally well to molecules containing more than one unpaired electron (S ≥ 1). States with S = 1/2 are referred to as doublet states since the multiplicity (2S + 1) is equal to 2.