The anomalous Zeeman effect is splitting into an even number of levels (not predicted by angular momentum alone) for Z odd atoms. This is evidence for spin. is the hamiltonian of the effect. .

If you turn off the magnetic field, there is still an effect: because of the magnetic field generated by the moving electrons.

The wigner eckhart theorem is

so = so all vector operators are proportional to

Want to find . Consider . This means: y.

in our paricular case: . so for = lande g-factor.

source psfile jl@crush.caltech.edu index particle_spin