I have a trouble understanding how s-subshell electrons can form a triplet state ever.
In general isn't it true, that there are only two cases for s-state:
- $\ell=0$, $s=1/2$, $J=1/2$ - doublet (one electron, hydrogen)
- $\ell=0$, $s=0$, $J=0$ - singlet (two electrons, helium)
So, s-state is always a singlet state when it is not a hydrogen. But how on Earth it can form a triplet? Pauli exclusion principle wouldn't allow two spin-up electrons on s-subshell, no?
Essentially, I reference p.90 of this