Spin (physics)

In physics, spin is an intrinsic angular momentum associated with microscopic particles. It is a purely quantum mechanical phenomenon without any analogy in classical mechanics. Whereas classical angular momentum arises from the rotation of an extended object, spin is not associated with any rotating internal masses, but is intrinsic to the particle itself. Elementary particles such as the electron can have non-zero spin, even though they are believed to be point particles possessing no internal structure. The concept of spin was introduced in 1925 by Ralph Kronig, and independently by George Uhlenbeck and Samuel Goudsmit.

Spin multiplets

Spin multiplets are groups of quantum states of the same total spin S, which are distinguished by different values of the quantum number Sz, ie, the spin component in the z-direction. Since there are 2S+1 such states, one speaks of spin singlet for an S=0 state, spin doublet, for S=½ and spin triplet for S=1. A similar nomenclature also holds for isospin.

Related Topics:
Quantum states - Quantum number - Isospin

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