NMR Spin

Spin is defined as angular moment associated with subatomic particles. All the protons, comprising any atomic nucleus, have the intrinsic quantum property of spin, an intrinsic angular momentum analogous to the classical angular momentum of a top (A conical child’s plaything tapering to a steel point on which it can be made to spin). or spinning sphere. The overall spin of the nucleus is determined by the quantum number S. If the numbers of both the protons and neutrons in a given nuclide are then S = 0 or no spin. For nuclei of even mass number, the multiple is an integer; for those of odd mass number, the multiple is a half-integer. In quantum mechanics spin is now recognized as an intrinsic property of all subatomic particles. Spin is one of the main criteria used to classify particles into two main groups: fermions, with half-integer values of spin (1/2,  3/2, …), and bosons, with integer values of spin (0, 1, 2,…). In the Standard Model all of the “matter” particles (quarks and leptons) are fermions, whereas “force” particles such as photons are bosons. These two classes of particles have different symmetry properties that affect their behaviour.