Question

is there any relation between fine struckture zeeman effect .how can i understand the coupling scheme

Answer 1

an electron in atom has two angular momenta:
1.orbital angular momentum due to the orbital motion of the electron around the nucleus.
2. spin ang. momentum due to the spin motion of the electron.
Fine structure:
The orbital motion of the electron around the nucleus give rise to a large internal magnetic field. the intrinsic magnetic moment of the electron due to its spin interacts with this spin internal magnetic field, which leads to the modification of the energy levels of the atom.
note that to occur fine structure splitting both Total spin angular momentum 'S' and total orbital angular momentum 'L' should be non zero.

zeeman effect is the splitting of energy level due to interaction between magnetic moment of atom and external field. Here the applied field should be weak so that the L-S coupling do not break. In strong field the coupling between L and S loses its significance. In such a case L and S are quantised separately and precess separately about the external field absolutely independent of each other.

zeeman effect is of two types: normal zeeman effect and anomalous.
normal zeeman (splitting of single line in maximum three lines) effect occur with atoms having total spin angular momentum zero. in this case total orbital angular momentum interact with applied external field resulting in modification of its energy levels.
\[\Delta E =-\mu_l.B\]

In anamalous zeeman effect the spin of the electron is also taken into account "S not zero". and thereby spectral line split up into more than three lines.\[\Delta E =-(\mu_l +\mu_s).B\]

Answer 2

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