Discussion Overview
The discussion centers on the transition from the 3P1 to 3S1 state in Helium, specifically why this transition is considered forbidden despite being seemingly permissible according to atomic selection rules. The scope includes theoretical aspects of atomic transitions and selection rules.
Discussion Character
Main Points Raised
- One participant notes that the transition from 3P1 (m=0) to 3S1 (m=0) is forbidden, referencing a lecture where this fact was used to measure the fine structure constant.
- Another participant mentions that the Clebsch Gordan coefficient for the combination of states with m=0 vanishes due to antisymmetry.
- A third participant questions whether the selection rules account for the vanishing of matrix elements, suggesting that these rules may not fully capture the underlying reasons for the transition's prohibition.
- A later reply asserts that Wikipedia may have omitted some relevant details regarding the selection rules.
Areas of Agreement / Disagreement
Participants express differing views on the completeness and applicability of the selection rules in explaining the transition's forbidden status, indicating that multiple competing perspectives remain unresolved.
Contextual Notes
There are limitations regarding the assumptions made about the selection rules and the implications of the Clebsch Gordan coefficients, which are not fully explored in the discussion.