JJ COUPLING

OR STRONG SPIN-ORBIT COUPLING

In nuclear and atomic physics, specific interdependence existing among the constituent subatomic particles in a nucleus (protons and neutrons) or in an atom (nucleus and electrons) that determines the total angular momentum.

In jj coupling, it is assumed that the predominant interaction is between the spin angular momentum and the orbital angular momentum of the same individual subatomic particle and that these two must be combined to yield the total angular-momentum quantum number j of the individual particle before the individual j´s are added in turn to obtain the total angular-momentum quantum number of the specific nucleus or atom.