Mechanistic studies on the formation of trifluoromethyl sulfur pentafluoride, SF5CF3--a greenhouse gas.

The formation of SF5CF3(X1A'), through the radical-radical recombination of SF5(X2A1) and CF3(X2A1), was observed for the first time in low-temperature sulfur hexafluoride-carbon tetrafluoride matrices at 12 K via infrared spectroscopy upon irradiation of the ices with energetic electrons. The nu1 fundamentals of the SF5(X2A1) and CF3(X2A1) radicals were monitored at 857 and 1110 cm-1, respectively; the newly formed trifluoromethyl sulfur pentafluoride molecule, SF5CF3(X1A'), was detected via its absorptions at 846 and 1160 cm-1. This formation mechanism suggests that a source for this potentially dangerous greenhouse gas might be the recombination of SF5(X2A1) and CF3(X2A1) radicals on aerosol particles in the terrestrial atmosphere.