The pictures below show the fine structure and the Zeeman effect on the ground states of the oxygen atom. These are 3×3=9 of these states in a multiplet of Lnet=1 and Snet=1. The spin-orbit coupling splits this multiplet into 3 not-quite-degenerate multiplets of Jnet=2, 1 , or 0, and in a magnetic field the Zeeman effect completely lifts the degeneracy of the 9 states.
Weak-field Zeeman effect:
Paschen–Back limit of strong magnetic field:
