Hmm. I'd imagine all matter than interacts with photons to be GHGs in some format. The frequency band for absorption and emission might be different, but the h

Hmm. I'd imagine all matter than interacts with photons to be GHGs in some format. The frequency band for absorption and emission might be different, but the helium could absorb a shorter wavelength, then release a longer wavelength (not infrared) that can be absorbed by something else, then emitted yet again to be infrared