I am not sure if this goes in this group but was discussing global warming and noted that if CO2 was not a greenhouse gas CO2 lasers would not work. He noted that if methane was so much more absorbent why not have methane lasers?
I suppose that the methane might break up or some other problem, but it does raise a question if methane lasers are possible and I thought that this is the best concentration of experts on the subject I know of.
I never say never, I have learned better. That said, it looks like this person is looking at one small aspect of Co2 lasers and then making an assumption that is not in evidence.
Calling a Co2 laser a Co2 laser is a lot like naming a semiconductor for what it is doped with. The primary “active ingredient” in a Co2 laser is nitrogen that works in concert with the Co2.
If someone has a more definitive answer I want to see it!
Isn’t methane pretty explosive/flammable?
Very flammable. I can’t find any references for lasing methane itself, but there are laser-based methane leak detectors on the market.
Just don’t tell cows that they are flammable…it spooks them 
My WAG is that the volatile nature of methane would preclude that possibility.
You have to admit that it produced a damn fine beam before the tube exploded.
How a CO2 laser works.
That would be a good reason to not park a candle behind a cow when milking it.
But methane and nitrogen together in a sealed environment should not be a problem unless it started making cyanide. I expect however the concept has been thought of and tried in several variations that were not viable or they would be using them.
However I did not know the answer and thought I might ask here.
It is possible to synthesize excited bromide in an argon matrix.
It would be like lasing a stick of dynamite. 
CO2 lasers work because molecules have a couple of energy levels separated by the right amount to generate a useful wavelength of light, and those levels have lifetimes conducive to massively overpopulating the higher energy level so that you can get lot of photons emitted in synch with one another.
Don’t know whether methane molecules have any similar sets of energy levels, but if they did a methane laser would be possible. (And you don’t really worry about methane going boom/bang in such a situation because there’s typically no free oxygen or other stuff in the laser tube for it to react with.) It’s not really about being a greenhouse gas except insofar as that means having some energy levels that give you absorption/emission in the infrared.
Here is a better link on how CO2 lasers work:
Laser is an acronym for Light Amplification by Stimulated Emission of Radiation. Basically, energy is pumped into a gas (or crystal for Ruby lasers). The lasing material is chosen for it’s ability to sustain a population inversion - where more molecules are excited (high energy) than not (low energy). When one of the molecules releases a photon at just the right energy and direction, it encourages the other molecules to release an identical photon, producing a beam of highly coherent light.
The lasing material is fitted with mirrors at both ends (one fully reflective and one partially transmissive) to provide direction to the beam.
I believe that, while CO2 is the part of the laser gas that does the work, there’s not actually very much in there. In fact there’s so little that if you cracked open the laser tube and just let air in, the amount of CO2 would increase!
Interesting. Do you have any idea if the tube pressure is above or below atmospheric? I would guess below from what you said.
That is why I used the metaphor of naming after the doping of a semiconductor. Nitrogen laser just wouldn’t sound cool but it is my understanding that it is the nitrogen that is the primary element holding the energy in excited electrons.
As always, feel free to correct me if I am barking up the wrong electron shell.
I have no idea what greenhouse gas has to do with lasing capabilities of a gas…
Here’s a mixture that includes methane.
https://www.osapublishing.org/abstract.cfm?uri=LS-2016-JW4A.180
There are tons of gas, liquid and solid laser mediums…bet most are not greenhouse gases…
Extremely interesting and far more complex than I thought. Thank you everyone for your input
Exactly.
I think you’re on point with that.