# How can methane absorb infrared light within wide range of frequency but CO2 can't?

Methane is one of the most potent greenhouse gases in Earth's atmosphere.I saw a lot of answers related to it but lacks de facto exegesis to it.

• CO2 can absorb too. It is just that their ranges are different. Nov 6 '19 at 10:21

IR Spectra of Methane and Carbon dioxide are available in NIST. This is how real spectroscopy looked like before the focus shifted from true science to fancier presentations and instruments became black-boxes. Anyway, all you have to note both methane and carbon dioxide absorb quite strongly in the typical range of infrared light 400 to 3800 $$cm^{-1}$$. The question of wide range does not arise as you can see from the spectra, their absorption band positions are different. Methane's spectra is more complex just because it has more active vibrations (dipole moment change is non-zero) and one can see the fine rotational structure of methane but carbon's dioxide's rotational lines are not resolved.
• Sometime ago, someone asked here if I did not know LaTeX how could I publish in science? My answer was that most of good fundamental science was done when we had type-writers. Sorry to say these days, presentation matters more, I mean the quality of papers and journal covers look more like comic magazines. Just a fews ago, a Wiley journal suggested that we publish a cover, and the price $1000 dollars. Angew. Chem. charges$2000 for a cover. Nov 6 '19 at 17:03