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

[Twigg]

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.

 

[DrClaude]

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

 

[Twigg]

Fantastic article! Learned a lot! Thanks!