Zeeman Splitting of D1 and D2 lines

Let us consider the Zeeman splitting of resonance lines D1 & D2 of sodium lines.
These lines arises from the transition  2P1/2 —–> 2S1/2 and. 2P3/2 ——–>2S1/2.

 

 

 

 

 

 

 

The splitting of these terms may be displayed as :

 

 

 

 

 

 

 

 

Applying the selection rules :

We obtain four Zeeman components for the D1 line and six components for the D2 line.

The components corresponding to Mj,=0 are polarised with electric vectors
perpendicular to the field (σ-components).

The intensities of the Zeeman components are governed by the following rules :

(i) The sum of all transitions starting from any initial Zeeman level is equal to sum of all transition starting from any other level having the same n and I values.

(ii) The sum of all transitions arriving at any Zeeman level is equals to sum of all transitions arriving at any other level having the same n and I values.

The relative intensities are indicated by the heights of the lines drawn at the bottom of the fig. 2 above.