TIME-RESOLVED OBSERVATION OF THE FORMATION OF CF2O AND CFCLO IN THE CF2CL+O2 AND CFCL2+O2 REACTIONS - THE UNIMOLECULAR ELIMINATION OF CL ATOMS FROM CF2CLO AND CFCL2O RADICALS

The unimolecular elimination of chlorine atoms from CF2ClO and CFCl2O radicals has been observed at 238 and 298 K, and at 4-20 Torr total pressure by measurement of the rate of formation of the carbonyl halide product in real time. The fragment ion (CFO)+ was found to be specific for the detection of CF2O and CFClO and was monitored by time-resolved mass spectrometry in flash photolysis of mixtures of CF2ClBr or CFCl3 with O2 and NO. These two Cl atom elimination reactions were verified to be very facile, even at low temperatures. The rate constants were estimated by regression analysis of experimentally measured formation curves of CF2O and CFClO, and decay curves of CF2ClO2 and CFCl2O2 were determined in the same experiments. The estimated 298 K rate constants are (6.4 +/- 1.4) x 10(4) s-1 for CF2ClO and (1.2 +/- 0.4) x 10(5) s-1 for CFCl2O.