Atmospheric Carbon Tetrafluoride: A Nearly Inert Gas

Abstract

An analysis of existing thermodynamic, photochemical, and kinetic data indicates that the dominant sinks for atmospheric carbon tetrafluoride (CF₄) are in and above the mesosphere. Theoretical calculations predict an atmospheric residence time for CF₄ of over 10,000 years, about 100 times that for dichlorodifluoromethane (CF₂Cl₂) and monofluorotrichloromethane (CFC1₃). It is predicted that CF₄ will be well mixed through the stratosphere and mesosphere; only one or two parts of hydrogen fluoride in 10¹² are predicted in the high stratosphere as a result of the decomposition of CF₄. Although natural sources of CF₄ cannot be ruled out, there are several likely industrial sources that may account for its present concentration. The principal environmental effect of CF₄ could be the trapping of outgoing planetary infrared energy in its intense bands near 8 micrometers.