Why Don't CO2 Lasers Operate at 2400cm^-1?

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    Co2 Lasers
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SUMMARY

CO2 lasers operate primarily in the wavelength range of 9µm to 11µm, corresponding to approximately 1000cm^-1, due to practical lasing criteria that favor these vibrational transitions over the 2400cm^-1 peak observed in the IR absorbance spectrum of dry air. The lasing transitions do not utilize the ground state, resulting in different frequencies than those seen in the IR spectrum. A reference that provides a comprehensive introduction to CO2 laser theory is available at the Berkeley website, specifically on page 114 of the linked document.

PREREQUISITES
  • Understanding of vibrational transitions in gases
  • Familiarity with infrared spectroscopy
  • Basic knowledge of laser operation principles
  • Access to CO2 laser theory literature
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  • Research the principles of CO2 laser operation and its vibrational modes
  • Study the IR absorbance spectrum and its implications for laser design
  • Explore the differences between ground state and excited state transitions in lasers
  • Review the referenced article on CO2 lasers for deeper insights
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Physicists, laser engineers, and students studying optics and photonics who seek to understand the operational principles of CO2 lasers and their applications in various fields.

Twigg
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Hi all,

When you look at the IR absorbance spectrum of dry air, there's a big peak at ~ 2400cm^-1 due to vibrational transitions in CO2. But CO2 lasers always operate in the region between 9um and 11um, which is about 1000cm^-1 by my math. What are the practical criteria that make the ~1000um vibrational peak better than the 2400um vibrational peak for lasing?

Can anyone refer me to a reference on and/or introduction to the theory of the CO2 laser that would answer this question?

Thanks in advance for helping me out with this beginner question.
 
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The lasing transitions do not use the ground state, hence the frequencies are different than those seen in the IR spectrum. See page 114 of http://socrates.berkeley.edu/~phylabs/adv/ReprintsPDF/CO2%20Reprints/03%20-%20CO2%20Lasers.pdf
 
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Fantastic article! Learned a lot! Thanks!
 

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