Spin (I)

The nuclear spin is designated by I, and its values are positive integers (0, 1, 2,...) and half-integers (1/2, 3/2, 5/2,...). Only nuclides with I>0 can be observed by NMR. Nearly all elements on the Periodic Table have at least one NMR-active nuclide, but the information that can be obtained varies widely. If an element has a spin-1/2 nuclide, that is generally the one preferred for NMR analysis, because it will tend to give narrower resonances. Nuclei with I>1/2 have a quadrupole moment, which usually results in broader peaks.