Photochemistry of perfluoroacetyl fluoride -: Kinetics of the reaction between CF3 and FCO radicals

The photolysis at 254 nm of perfluoroacetyl fluoride (CF3COF) in the gas phase yields C2F6, CF2O and CO as products. An excess of O-2 added to the system leads to the formation of CF2O and CO2 as main products. If, instead of O-2, c-C6H12 were added, the main products are CF3H and HC(O)F In both cases a faster rate of CF3COF dissapearance is observed. The measurement of the quantum yield for CF3COF consumption as well as for products formation are: for CF3COF alone, phi(CF3COF) = 2 phi(C2F6) = 2 phi(CF20) = 0.43 +/- 0.05; in the presence of c-C6H12 phi(CF3COF) = phi(CF3H) = 1.02 +/- 0.02 and in the presence of O-2, phi(CF3COF) = 1.02 +/- 0.05 The low quantum yield observed for pure CF3COF suggests the occurence of the recombination reaction: CF3 + FCO --> CF3COF for which we calculated the rate constant as (6.9 +/- 0.8) x 10(-12) cm(3) molecule(-1) s(-1). (C) 1999 Elsevier Science S.A. All rights reserved.