Electron transitions within the same excited state?

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Discussion Overview

The discussion revolves around the possibility of electronic transitions within the same excited state, specifically focusing on electronic dipole transitions and selection rules. Participants explore the implications of these rules on transitions between specific states, such as ^4P_1/2 and ^4P_2/3, both in the n=3 shell.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant, Toby, questions whether transitions can occur between ^4P_1/2 and ^4P_2/3 within the same excited state, citing uncertainty about the role of the selection rule pi_f = -pi_i.
  • Another participant suggests looking into the Laporte Rule, indicating it may apply to transitions within the same subshell.
  • A different participant asserts that the first selection rule, Δl = ±1, is a strong rule due to conservation of angular momentum, implying that transitions within the same state are not possible.
  • There is a mention of the 21 cm hydrogen line, which is associated with a transition between the same 1s state, but it is clarified that this is not an electric dipole transition.

Areas of Agreement / Disagreement

Participants express differing views on the possibility of transitions within the same excited state. While some suggest that certain rules may allow for such transitions, others firmly state that selection rules prohibit them. The discussion remains unresolved with multiple competing perspectives.

Contextual Notes

Participants reference selection rules and the Laporte Rule, but there is no consensus on their applicability to the specific transitions discussed. The implications of these rules on atomic versus molecular transitions are also noted as a point of contention.

pingaan
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Hi,

I am have trouble finding whether or not the topic is possible.
It concerns an electronic dipole.

I am well familiar with the general rules: https://en.wikipedia.org/wiki/Selection_rule

Is it possible for transitions to occur from e.g. ^4P_1/2 and ^4P_2/3, which are both in n=3?
If they were in two different excited states it would be possible, this I know, but I am unsure of whether or not the rule pi_f = -pi_i plays a role when a possible transition would occur within the state. If it does then it is a matter of pi_f = pi_i, which is not allowed in an electric dipole.

Any help would be greatly appreciated!

Regards,
Toby
 
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Have you looked into the Laporte Rule? I'm well outside of my expertise area, but it appears to cover transitions within the same subshell.
 
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Drakkith said:
Have you looked into the Laporte Rule? I'm well outside of my expertise area, but it appears to cover transitions within the same subshell.

Thanks, I'll have a look at it! 👍
 
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pingaan said:
Is it possible for transitions to occur from e.g. ^4P_1/2 and ^4P_2/3, which are both in n=3?
No, the first rule is ##\Delta l = \pm 1##. Since it is due to conservation of angular momentum (the spin of the absorbed photon must be transferred to the atom), this is a strong rule, meaning that there aren't many ways of breaking the selection rule even by going beyond the dipole approximation.
 
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Drakkith said:
Have you looked into the Laporte Rule? I'm well outside of my expertise area, but it appears to cover transitions within the same subshell.
That's for molecules. I think we are dealing with atomic transitions here.
 
DrClaude said:
That's for molecules. I think we are dealing with atomic transitions here.
Noted. Thx, DC.
 
well, the famous 21 cm hydrogen line is associated with the transition between 1s to 1s, the difference comes from parallel to antiparallel aligning of the elecron spon with the proton spin.
 
Henryk said:
well, the famous 21 cm hydrogen line is associated with the transition between 1s to 1s, the difference comes from parallel to antiparallel aligning of the elecron spon with the proton spin.
Which is not an electric dipole transition.
 

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