What determines the absorption strength in molecular bands?

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SUMMARY

The absorption strength in molecular bands is determined by several key factors, including temperature, density, and oscillator strength of the transition. In infrared spectra, certain lines may exhibit partial absorption that transitions to full absorption at the center of the absorption feature. Specifically, the population of energy levels in molecules, influenced by temperature, plays a crucial role in determining whether a spectral line is fully or partially absorbed. This understanding is essential for interpreting H2O spectra accurately.

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  • Understanding of molecular spectroscopy
  • Knowledge of infrared spectroscopy techniques
  • Familiarity with oscillator strength concepts
  • Basic principles of thermodynamics related to temperature and density
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  • Research the role of temperature in molecular level populations
  • Explore the concept of oscillator strength in detail
  • Study the principles of infrared spectroscopy
  • Examine case studies of H2O spectral analysis
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Researchers in molecular spectroscopy, chemists analyzing infrared spectra, and students studying the principles of absorption in molecular bands.

nordmoon
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I have a very basics question.

I have a question about absorption in molecular bands. When looking at spectra in the infrared region and comparing it with simulated spectra, I can see that some lines get partially absorbed and then grows to fully absorbed in the "center" of the absorption feature. Also some lines to be fully absorbed and some lines seem to be only partially absorbed in H20 spectra.

What determines if a spectral line is fully absorbed or only partially?

Has it to do with the temperature and how much is occupied in a certain level in the atom or molecule?
 
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Yes, the level populations are determined by the temperature and density. The strength of the line is also determined by the oscillator strength of the transition.
 

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