Exchange symmetry splitting in Helium

[sachi]

In Helium we find that each energy level specified by (n,l) splits into two sub levels, a singlet and a triplet (this triplet is supposed to be degenerate)
I'm sure that this triplet does not turn out to be degenerate because of fine structure. But I'm not sure if the fine structure splitting is smaller than the exchange symmetry splitting. If so, then we should find an observed triplet with small energy differences. If the fine structure splitting is greater than the exchange splitting, then we shouldn't even find a clear singlet - triplet patterm.
thanks very much for your help.

 

[Jhero]

Thank you for bringing up this interesting topic. I can confirm that the singlet and triplet sublevels in Helium do indeed exist and are a result of the fine structure of the atom. The fine structure splitting is caused by the interaction of the electron's spin with its orbital angular momentum, resulting in a slight difference in energy levels.

However, you are correct in your assumption that the fine structure splitting is smaller than the exchange symmetry splitting. The exchange symmetry splitting is caused by the repulsion between two electrons occupying the same orbital, resulting in an even smaller energy difference between the singlet and triplet sublevels.

In fact, the exchange symmetry splitting is about 1/10th of the fine structure splitting, making it difficult to observe in experiments. This is why we mainly focus on the fine structure splitting when studying the energy levels of Helium.

I hope this helps clarify any confusion and thank you for your interest in this topic. Keep exploring and questioning, as that is the essence of science. Happy researching!