Answer to Question #228482 in Atomic and Nuclear Physics for Faz

Question

Q. 5. (6,9)
(a) On which lines normal Zeeman effect, Anomalous Zeeman effect and Paschen-Back
effect differs?

Answer 1

The Zeeman effect of the hydrogen atom shows the expected equally-spaced triplet (= "normal" Zeeman effect).

On the other hand, the sodium D lines (D1 and D2 doulet) show "anomalous" Zeeman effect ( due to the many inner electrons).

It is said that the normal Zeeman effect is observed in the spin zero states.

But also in the normal Zeeman effect, we can not neglect the electron spin (in the quantum mechanics).

So to be precise, the normal Zeeman effect of the hydrogen atom in Fig.1 is "Paschen - Back effect" (Fig.2 and 3).

In the Paschen-Back effect, when the external magnetic field is stronger than the fine structure's level (= spin-orbital interaction level), the orbital and spin angular momenta become "quantized" in the direction of the magnetic field (B) (See Fig.2).

 Paschen-Back effect also shows the equally-splitted triplet lines.