NMR Isotopes and Frequencies. 1 Select Frequency / Field 1 H Larmor Frequency MHz Magnetic Field Tesla 2 Spin Type spin 1/2 nuclei integer spins (1,3,6,7) spin 3/2 nuclei spin 5/2 nuclei spin 7/2 nuclei spin 9/2 nuclei. Based on the IUPAC-recommended data, Pure Appl. Chem., 73, 2001, 1795-1818, by Harris, Becker, De Menezes, Goodfellow and Granger.