Rotational translations between L values and spectral lines

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SUMMARY

The discussion focuses on determining the L values corresponding to specific spectral lines of the HCl molecule, observed at wave numbers 85.03, 103.73, 124.30, 145.03, 165.51, and 185.86 cm-1. The relationship w = h-bar(L + 1)/I is central to this analysis, with w representing angular frequency and I the moment of inertia. Participants suggest using the proportionality of ω to wave number and recommend graphing the wave numbers to identify patterns that may assist in calculating the L values.

PREREQUISITES
  • Understanding of quantum mechanics, specifically rotational spectroscopy
  • Familiarity with the relationship between angular frequency and wave number
  • Knowledge of the HCl molecular structure and its spectral lines
  • Basic graphing techniques for data analysis
NEXT STEPS
  • Explore the concept of rotational quantum numbers in molecular spectroscopy
  • Learn how to calculate moment of inertia for diatomic molecules like HCl
  • Investigate the method of graphing spectral lines to identify trends
  • Study the application of the equation w = h-bar(L + 1)/I in practical scenarios
USEFUL FOR

This discussion is beneficial for physicists, chemists, and students studying molecular spectroscopy, particularly those interested in analyzing spectral lines and their corresponding quantum states.

jonesy101
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The question: Given that w=h-bar(L+1)/I. Suppose that we observe spectral lines from the HCl molecule at wave numbers (in cm^-1) 85.03, 103.73, 124.30, 145.03, 165,51 and 185.86 (wavenumber here is simply in the inverse wavelength lambda^-1). What L values do these lines correspond to?

My attempt: Knowing that w=2*pi*c/lambda I tried to set up a ratio between to wavenumbers and relate it to the original equation but couldn't find a set of integrals for L that matched my ratios. I don't know what to do.

Please help!
 
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jonesy101 said:
The question: Given that w=h-bar(L+1)/I. Suppose that we observe spectral lines from the HCl molecule at wave numbers (in cm^-1) 85.03, 103.73, 124.30, 145.03, 165,51 and 185.86 (wavenumber here is simply in the inverse wavelength lambda^-1). What L values do these lines correspond to?

My attempt: Knowing that w=2*pi*c/lambda I tried to set up a ratio between to wavenumbers and relate it to the original equation but couldn't find a set of integrals for L that matched my ratios. I don't know what to do.

Please help!
Perhaps you just need to allow for a little measurement error. You know ω is proportional to wave number (inverse wavelength). Try graphing those wave numbers and see what you get.
 

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