Anomalous Zeeman Effect, an Example

Consider an emission transition between an upper 2P1/2 term and a lower 2S1/2 term (e.g., the D1 line in the spectrum of Na I):

 

 

 

 

Comparison of Terms
Quantity 2P3/2 Term 2S1/2 Term
S 1/2 1/2
L (P) = 1 (S) = 0
J 1/2 1/2
g = 1 + [J(J+1) + S(S+1) - L(L+1)]/[2J(J+1)] 2/3 2
ΔE = h Δν MJ g (2/3)h Δν MJ 2h Δν MJ

 

                           

                                                                                                

                                                                                                               
 

 

 

                                                                                     ΔMJ  =  0          1        -1          0
                                                           Component Type       π         σ         σ         π

                                                 δν = ν - ν0 = (E - E0)/h  = (-2/3)Δν  (4/3)Δν  (-4/3)Δν  (2/3)Δν 

                       where Δν = "Larmor frequency" = eH / (4πmec)

 

                                                                                           
Emission line in the absence of a magnetic field:

Emission line for observer looking normal to field lines:

Emission line for observer looking parallel to field lines:

                                                                                                                                           σ    π         π    σ
                                                                                                                              ΔMJ  =  -1     0           0     1