Hyperfine structure with several nuclei

Chemical bonds can have covalent character, and EPR spectroscopy is an excellent tool to study covalency An unpaired electron can be delocalized over several atoms of a molecular structure, and so its spin S can interact with the nuclear spins /, of all these atoms. These interactions are independent and thus afford additive hyperfine patterns. An unpaired electron on a Cu2+ ion (S = 1/2) experiences an / = 3/2 from the copper nucleus resulting in a fourfold split of the EPR resonance. If the Cu is coordinated by a... 

The nucleus to which the parameters belong is characterized by its chemical symbol, a left superscript may indicate the isotope, if another than the most abundant is meant. Entries within parentheses after the chemical symbol specify different positions of the nucleus in the radical (e.g. 0(2) The values belong to the isotope O in position 2 of the structural formula). If several nuclei with the same chemical symbol couple with the same hyperfine coupling constants the parameters are given only once and the number of equivalent nuclei is stated before the chemical symbol (e.g. 3H The values belong to 3 equivalent H atoms of the molecule). 

The methods of nuclear magnetic resonance (NMR) and of Mossbauer effect or nuclear gamma resonance (NGR) spectroscopy furnish a broad basis for the study of the structural, electronic, and magnetic properties of rare-earth metals, alloys, and compounds. Taken together, there is hardly a rare-earth or non rare-earth nucleus whose hyperfine interactions cannot be measured. In many cases, results can be cross-checked with measurements on several isotopes of the same element. 

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