[P CHem] HCL/DCL r and p branch J value assignment

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SUMMARY

The discussion focuses on assigning J values for the P and R branches of HCl/DCl compounds, specifically H35Cl, H37Cl, D35Cl, and D37Cl. It clarifies that R branch J values can be 0, 1, 2, 3, etc., while P branch J values start at 1, 2, 3, etc. The participant identifies the P branch by observing that wave numbers become more spread out as they decrease. Additionally, the participant notes that the less intense peaks correspond to the less common isotopes, H37Cl and D37Cl, due to their lower abundance affecting intensity.

PREREQUISITES
  • Understanding of IR spectroscopy and its application to molecular compounds.
  • Familiarity with the concepts of rotational spectroscopy and J values.
  • Knowledge of isotopic effects on spectral intensity.
  • Basic skills in analyzing wave numbers and their relation to molecular transitions.
NEXT STEPS
  • Research the principles of rotational spectroscopy and how J values are assigned.
  • Study the differences between P and R branches in molecular spectra.
  • Learn about the effects of isotopes on IR spectra and peak intensities.
  • Explore advanced techniques for analyzing IR spectra, including software tools for spectral analysis.
USEFUL FOR

Students and researchers in chemistry, particularly those studying molecular spectroscopy, as well as professionals working with isotopic compounds and their spectral characteristics.

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Homework Statement


Assign J values for P and R branches of H35cl, H37cl, d35cl, and d37cl compounds.


Homework Equations





The Attempt at a Solution


I have a fundamental IR spectra I did on and HCL/DCL compound. I'm extremely confused how to assign J values. I've been looking online and see R can be 0, 1, 2, 3, etc but P starts at 1,2,3, etc. How did they assign these values?

What I do know
I peaked picks so I know the wave numbers.
I can tell the P branch form the R because as the wave numbers get smaller they get more spread out.
I know the less intense peaks of the doublets are the H37CL or D37CL b/c it is a less common isotope and intensities are based on number of species.
 
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I'm stuck here too! How do you go from wave numbers to j values. What's the difference between j and j'?
 

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