Laboratory evidence for a key intermediate in the Venus atmosphere: Peroxychloroformyl radical

For two decades, the peroxychloroformyl radical, CIC(O)OO, has played a central role in models of the chemical stability of the Venus atmosphere. No confirmation, however, has been possible in the absence of laboratory measurements for CIC(O)OO. We report the isolation of CIC(O)OO in a cryogenic matrix and its infrared and ultraviolet spectral signatures. These experiments show that CIC(O)OO is thermally and photolytically stable in the Venus atmosphere. These experimental discoveries validate the existence of CIC(O)OO, confirm several longstanding model assumptions, and provide a basis for the astronomical search for this important radical species.