Absolute rate constants for F+CH3CHO and CH3CO+O2, relative rate study of CH3CO+NO, and the product distribution of the F+CH3CHO reaction

Using a pulse-radiolysis transient UV-VIS absorption system, rate constants for the reactions of F atoms with CH3CHO (1) and CH3CO radicals with O-2 (2) and NO (3) at 295 K and 1000 mbar total pressure of SF6 was determined to be k(1) = (1.4 +/- 0.2) x 10(-10), k(2) = (4.4 +/- 0.7) X 10(-12), and k(3) = (2.4 +/- 0.7) X 10(-11) cm(3) molecule(-1) s(-1). By monitoring the formation of CH3C(O)O-2 radicals (lambda > 250nm) and NO2 (lambda = 400.5 nm) following radiolysis of SF6/CH3CHO/O-2 and SF6/CH3CHO/O-2/NO mixtures, respectively, it was deduced that reaction of F atoms with CH3CHO gives (65 +/- 9)% CH3CO and (35 +/- 9)% HC(O)CH2 radicals. Finally, the data obtained here suggest that decomposition of HC(O)CH2O radicals via C-C bond scission occurs at a rate of <4.7 X 10(5) s(-1). (C) 1998 John Wiley & Sons, Inc.