The unimolecular decomposition CF3C1 + Kr -CF3 + C1 + Kr has been studied using two different techniques, atomic resonance absorption spectrometry (ARAS) and laser schlieren (LS) density gradients, in two laboratories. As in our previous joint investigation of C C 4 dissociation, the ARAS and LS techniques give completely consistent results over the overlapping temperature range, 1800-2200 K. The title reaction is found to be fairly close to the low-pressure limit. The ARAS measurements between 1521 and 2173 K give k2nd = 1.73 x IO-' exp(-33837K/T) cm3 molecule-' s-l ( f 2 7 % at lo). This is in good agreement with the earlier ARAS measurements of b g e r and Wagner. k2nd = 1.15 x exp(-28330K/T) cm3 molecule-' s-' ( f 2 0 % at l o ) is obtained from the LS results between 1800 and 3000 K. The good agreement between methods verifies both the C-C1 fission path for the CFX1 dissociation and the curve-of-growth used in the C1 atom ARAS analysis. RRKM analysis of these rate data indicated a larger than usual magnitude for hEdown, in agreement with our previous findings on CC4, but here it was necessary that it increase with T.The best fit was with = 270 cm-'. The RRKM fit to the data is given by the three-parameter expression k2nd = 2.95 x 1024T8.50 exp(-48133K/7') cm3 molecule-' s-l for a pressure of 300 Torr. This final expression agrees with both the ARAS and LS results to within f 2 5 % and can be used in modeling applications between 1500 and 3000 K. IntroductionC1 atom ARAS,8 and we can also compare with these results.

The processes of vibrational relaxation and unimolecular dissociation of the perfluoromethyl halides CF 3 Cl, CF 3 Br, and CF 3