ATMOSPHERIC CHEMISTRY OF ACETONE - KINETIC-STUDY OF THE CH3C(O)CH2O2+NO NO2 REACTIONS AND DECOMPOSITION OF CH3C(O)CH2O2NO2/

Pulse radiolysis was used to study the kinetics of the reactions of CH 3C(O)CH2O2 radicals with NO and NO2 at 295 K. By monitoring the rate o f formation and decay of NO2 using its absorption at 400 and 450 nm th e rate constants k(CH3C(O)CH2O2 + NO) = (8 +/- 2) X 10(-12) and k(CH3C (O)CH2O2 + NO2) = (6.4 +/- 0.6) x 10(-12) cm(3) molecule(-1) s(-1) wer e determined. Long path length Fourier transform infrared spectrometer s were used to investigate the IR spectrum and thermal stability of th e peroxynitrate, CH3C(O)CH2O2NO2. A Value of k(-6) approximate to 3 s( -1) was determined for the rate of thermal decomposition of CH3C(O)CH2 O2NO2 in 700 torr total pressure of O-2 diluent at 295 K. When combine d with lower temperature studies (250-275 K) a decomposition rate of k (-6) = 1.9 x 10(16 )exp (-10830/T) s(-1) is determined. Density functi onal theory was used to calculate the IR spectrum of CH3C(O)CH2O2NO2. Finally, the rate constants for reactions of the CH3C(O)CH2 radical wi th NO and NO2 were determined to be k(CH3C(O)CH2 + NO) = (2.6 +/- 0.3) x 10(-11) and k(CH3C(O)CH2 + NO2) = (1.6 +/- 0.4) x 10(-11) cm(3) mol ecule(-1) s(-1). The results are discussed in the context of the atmos pheric chemistry of acetone and the long range atmospheric transport o f NOx. (C) John Wiley & Sons, Inc.