Atmospheric Carbon Tetrafluoride: A Nearly Inert Gas

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Abstract
An analysis of existing thermodynamic, photochemical, and kinetic data indicates that the dominant sinks for atmospheric carbon tetrafluoride (CF 4 ) are in and above the mesosphere. Theoretical calculations predict an atmospheric residence time for CF 4 of over 10,000 years, about 100 times that for dichlorodifluoromethane (CF 2 Cl 2 ) and monofluorotrichloromethane (CFCl 3 ). It is predicted that CF 4 will be well mixed through the stratosphere and mesosphere; only one or two parts of hydrogen fluoride in 10 12 are predicted in the high stratosphere as a result of the decomposition of CF 4 . Although natural sources of CF 4 cannot be ruled out, there are several likely industrial sources that may account for its present concentration. The principal environmental effect of CF 4 could be the trapping of outgoing planetary infrared energy in its intense bands near 8 micrometers.