CO₂ Spectrum
From Global Warming, Understanding The Forecast by David Archer, Blackwell 2007, without permission. Buy the book for a lucid explanation of the science; perhaps the author and publisher might forgive me for posting the excerpt below.
I don't understand cycles/cm very well. The speed of light is 3e10 cm/s, so multipliy 600 to 800 cycles/cm to get 18 to 24 THz.
Here's the CO₂ absorption spectrum from NIST: ( http://webbook.nist.gov/cgi/cbook.cgi?ID=C124389&Type=IR-SPEC&Index=1#IR-SPEC )