Atmospheric oxidation of C10∼14 n-alkanes initiated by Cl atoms: Kinetics and mechanism

The Cl-initiated photo-oxidation reactions of n-alkanes: C-10 similar to C-14, were investigated by using Proton-Transfer-Reaction Mass Spectrometry in the smog chamber, and the present work provided the kinetic parameters of the reactions of Cl atoms with C-11 similar to 14 n-alkanes for the first time. The rate constants (in units of cm(3)molecule(-1)s(-1)) were obtained using relative rate method with trans-2-butene, m-xylene and ethylbenzene as references at (298 +/- 1)K and 760 Torr were k((n-decane))=(4.82 +/- 0.32) x 10(-10), k((n-undecane))=(5.02 +/- 0.33) x 10(-10), k((n-dodecane))=(5.12 +/- 0.29) x 10(-10), k((n-tridecone))=(5.30 +/- 0.30) x 10(-10), k((n-undecane))=(5.68 +/- 0.34) x 10(-10), respectively. The measured rate constants have also been used to calculate tropospheric lifetimes of these compounds (C-10, C-11, C-12, C-13, C-14), which were 11.5, 11.1, 10.9 10.5 and 9.8 h for each n-alkane. In addition, the gas-phase photooxidation products of the reactions were also measured. Based on the obtained results, the reaction mechanisms of Cl atoms with these five alkanes were proposed.