The nuclei of atoms can be likened in some respects to. elementary magnets. In a strong magnetic field, the different orientations that the elementary magnets assume correspond to different energies. Thus, transitions of die nuclear magnets between these different energy levels correspond to different frequencies of radiation in the short-wave, radio- frequency range. Hcncc, if an electrolytic solution is placcd in a strong magnetic field and an oscillating clcctromagnctic field is applied, the nuclcar magnets exchange energy (exhibit resonant absorption) when the incident frequency equals that for the transitions of nuclei between various levels.
Were this NMR to depend only on the nuclei of the species present in the solution, the technique would be without point for the identification of spccics in a solution. But the nucici sense the applied field as modified by the environment of the nucici. The modification is almost exclusively due to the nucici and electrons in the neighbourhood of the sensing nuclcus, i. c., due to the adjacent atoms and bonds. Thus, NMR studies can be used
(î provide information on the type of association between an ion and its environmental particles, c. g., on ion-solvent interactions or ion association.