Studies of the reaction processes of atmospheric minor constituents related to the global warming

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Absolute and relative rate techniques were used to study the reactivity of Cl atoms with cyclohexanone in 6 Torr of argon or 800-950 Torr of N2 at 295 2 K The absolute rate experiments gave k(Cl+cyclohexanone) = (1.88 0.38)×10^<-10> while the relative rate experiments gave k(Cl+cyclohexanone) = (1.66±026)×10^<-10> cm^3 molecule^<-1> s^<-1> methods. Cyclohexanone has a broad UV absorption band with a maximum cross section of (4.0±03)×10^-20 cm^2 molecule^<-1> near 285 nm The results are discussed with respect to the literature data.The kinetics and mechanism of the reaction Cl + CH_3 (CH_2)_3CHO was investigated using absolute (PLP-LIF) and relative rate techniques in 8 Ton of argon or 800-950 Ton of N_2 at 295± 2K. The absolute rate experiments gave k(C1 + CH_3(CH_2)_3CHO) = (2.31±0.35)×10^<-10> in 8 Ton of argon while relative rate experiments gave k(CI + CH_3(CH_2)_3CHO) = (2.24±0.20)×10^<-10> cm^3 molecule^<-1> s^<-1> in 800-950 Ton of N_2. Additional relative rate experiments gave … More k(Cl+CH_3(CH_2)_3C(O)CI) = (8.74± 1.38)×10^<-11> cm^3 molecule^<-1> s^<-1> in 700 Ton of N_2. Smog chamber Fourier transform infrared (F IR) techniques indicated that the acyl-forming channel accounts for 42 ± 3% of the reaction. The results are discussed with respect to the literature data and the importance of long range (= 2 carbon atoms along the aliphatic chain) effects in determining the reactivity of organic molecules towards chlorine atoms.The gas-phase reactions of Cl atoms with acetone, butanone, 2-pentanone, 3-pentanone, 2-hexanone, 3-hexanone, and cyclopentanone at 295±2 K were studied using pulsed laser photolysis vacuum UV laser-induced fluorescence (PLP-LIF) techniques. Cl(^2P_3/_2) atoms were produced by photolysis of Cl_2 at 351 nm and monitored by LIF spectroscopy at 134.72 nm (3p^5 2P_3/^2-3p^44s ^2_3/2 transition). Rate coefficients for reactions of Cl atoms with acetone, butanone, 2-pentanone, 3-pentanone, 2-hexanone, 3-hexanone, and cyclopentanone are : (2.30±0.12)×10_-12, (4.08±0.21)×10^<-11>, (1.23±013)-〜10^<-10>, (8.87s-0.92)40^<-1>1, (2.08±0.32)×10^<-10>, (1.43±0.19)×10^<-10> and (1.16±0.12)×10^<-10> cm^3 molecule^<-1>s^<-1>, respectively. The results for acetone and butanone are consistent with previous studies. The results for 2-pentanone, 3-pentanone, 2-hexanone, and 3-hexanone are approximately a factor of 2-3 higher than those from previous absolute rate studies. Likely explanations for these discrepancies are discussed. Tropospheric lifetimes of ketones with respect to reaction with Cl atoms are estimated and discussed. Less