J. Phys. Chem. 1996, 100, 15827-15833
15827
Thermal Decomposition of CF2HCl M.-C. Su,† S. S. Kumaran, K. P. Lim, J. V. Michael,* and A. F. Wagner Chemistry DiVision, Argonne National Laboratory, Argonne, Illinois 60439
D. A. Dixon‡ DuPont Central Research and DeVelopment, Experimental Station, Wilmington, Delaware 19880-0328
J. H. Kiefer and J. DiFelice Department of Chemical Engineering, UniVersity of Illinois at Chicago, Chicago, Illinois 60680 ReceiVed: May 8, 1996; In Final Form: July 15, 1996X
The development of a multipass optical absorption (MPA) technique for detecting CF2 radicals behind reflected shock waves and its application for studying the thermal dissociation of CF2HCl in Kr are reported. In an earlier work, a Cl atom atomic resonance absorption spectrometric (ARAS) study on the thermal decomposition of CF2Cl2 gave the stoichiometric yield of two Cl atoms per dissociating CF2Cl2, indicating the overall process is CF2Cl2 ) 2Cl + CF2. CF2 yields with CF2Cl2 as the thermal source were then used to obtain the CF2 curve of growth. The effective absorption cross section is 2.86 × 10-18 cm2 at 249.8 nm. In the CF2HCl experiments, the yield was measured to be 1.01 ( 0.06, confirming that the thermal decomposition pathway is molecular HCl elimination; i.e., CF2HCl (+ M) f CF2 + HCl (+ M). Above 1900 K, C-Cl bond fission was measured to be
