How to Assign J''-J' Values in Rotational Spectrum with Only Energy Value?

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SUMMARY

The discussion focuses on assigning J''-J' values in a rotational spectrum using only the energy value in cm-1. Participants emphasize the importance of the selection rules for rotational transitions, which dictate that J values can change by +/- 1. However, without the rotational parameter B or additional molecular information, accurately determining the J values from a single energy line is not feasible. The consensus is that more data is necessary to make definitive assignments.

PREREQUISITES
  • Understanding of rotational spectroscopy
  • Familiarity with selection rules for rotational transitions
  • Knowledge of molecular rotational parameters, specifically B
  • Basic concepts of energy levels in quantum mechanics
NEXT STEPS
  • Research the role of the rotational constant B in molecular spectroscopy
  • Study the derivation of energy levels in rigid rotor models
  • Explore methods for determining J values from spectral lines
  • Learn about the significance of molecular identity in spectral analysis
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Researchers in physical chemistry, spectroscopists, and students studying molecular spectroscopy who seek to understand the assignment of J''-J' values in rotational spectra.

jl29488
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If I have the energy value (in cm-1) of a specific line in the rotational spectrum, how do I find out/assign the correct J''-J' values?

I know the selection rules for J to be +/- 1 for each rotational transition but I'm not sure how you can correctly identify which J value it is if your only given the energy.. The rotational parameter B isn't specified either so I'm puzzled.

Any help?
 
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I don't think it is possible to assign anything to just a single line.
 
jl29488 said:
If I have the energy value (in cm-1) of a specific line in the rotational spectrum, how do I find out/assign the correct J''-J' values?

I know the selection rules for J to be +/- 1 for each rotational transition but I'm not sure how you can correctly identify which J value it is if your only given the energy.. The rotational parameter B isn't specified either so I'm puzzled.

Any help?
Do you know what the molecule is?
 

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