STRATOSPHERIC PHOTO-DISSOCIATION OF SEVERAL SATURATED PERHALO CHLORO-FLUOROCARBON COMPOUNDS IN CURRENT TECHNOLOGICAL USE (FLUOROCARBON-13, FLUOROCARBON-113, FLUOROCARBON-114, AND FLUOROCARBON-115)

Photon absorption cross sections have been measured in the stratospherically important 1849-2273-Å range for CClF3 (fluorocarbon-13), CCl2FCClF2 (FC-113), CClF2CClF2 (FC-114), and CClF2CF3 (FC-115). Atmospheric residence times have been calculated for these four compounds, and for CCl3F (FC-11) and CCl2F2 (FC-12), with the assumption that the molecules are removed only by direct solar photolysis or by reaction with O(1D) atoms. Four different eddy diffusion models were used for stratospheric mixing. Direct photolysis accounts for >90% of the removal of FC-11, >80% for FC-12 and FC-113, and <20% for FC-13 and FC-115. Direct photolysis and reaction with O(1D) atoms are roughly comparable in importance for the removal of FC-114. The calculated atmospheric residence times range from 40 to 550 years, with especially long calculated residence times for FC-13 and FC-115 which have very low photon absorption cross sections and which are therefore primarily removed from the stratosphere by reaction with O(1D) atoms. © 1978 American Chemical Society.