OBSERVATION OF THE CFCL2CH2O RADICAL IN THE FLASH-PHOTOLYSIS OF CFCL2CH3 IN THE PRESENCE OF O-2 - KINETICS OF THE REACTIONS OF CL AND CLO WITH CFCL2CH2O2 AND CH3CFCLO2

Photolysis of CFCl2CH3 (HCFC-141b) and CFCl2CH3/O-2/N-2 gas mixtures w as investigated at 4-60 Torr and 253-321 K by means of UV flash photol ysis and time-resolved mass spectrometry. Atomic chlorine was produced by the photolysis of CFCl2CH3. The concentration of Cl so formed was experimentally determined by NOCl trapping of the atoms. Observation o f the kinetic growth curve of the CFCl2CH2O radical and growth and dec ay of ClO permitted a kinetics study of the reactions of Cl and ClO wi th the peroxy radicals, CFCl2CH2O2 and CH3CFClO2, which were formed fo llowing the photolysis of CFCl2CH3 in the presence of oxygen. The pero xy radicals were removed by self-reactions and cross reactions and by reaction with Cl and ClO. The temperature dependence of the rate coeff icients of the CFCl2CH2O2 and CH3CFClO2 plus Cl reaction was estimated to be (6.1 +/- 0.3) x 10(-10)e((-779+/-55)/T) and (8 +/- 3) x 10(-11) e((-646+/-69)/T) cm(3) molecule(-1) s(-1), respectively. The rate coef ficients for the reactin of ClO with these peroxy radicals were estima ted to be (6.0 +/- 0.7) x 10(-12) cm(3) molecule(-1) s(-1) for CFCl2CH 2O2 and (4.5 +/- 1) x 10(-12) cm(3) molecule(-1) s(-1) for CH3CFClO2 o ver the temperature range of these experiments.