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 No, not phosphorescent. Phosphorescence, as far as I know, does not occur in gases. If you check the Wiki article it refers to the delay in re-emission characteristic of phosphorescence being ""associated with ""forbidden"" energy state transitions in quantum mechanics"", these transitions can only occur in solid materials. The IR absorption/emission associated with the so-called greenhouse gases is due to molecular vibrations that are directly related to the molecular temperature. Phosphorescence is not particularly dependent on temperature, whereas the absorption/emission of GHGs is an exact function of the temperature of the molecule.  "