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The C1-atom-initiated oxidation of CzHsCl has beem investigated at 295 K using Fourier transform infrared (FTIR) spectroscopy. The observed products are HCl, COz, CHsCOCl, HCHO, CO, CHsOH, HCOOH, CH300H, CH,C(O)OOH, and CHZCICHO. The yields of HCl and CO2 per CzHsCl consumed are surprisingly high, (1 57 f 6)% and (53 f 5)%, and are constant over the CZHsCl consumption range of 3-1 5%. To rationalize these results, we propose a new alkoxy radical decomposition pathway: the CH3CHClO radical intramolecularly eliminates HCl to produce the acetyl radical, CHsCO, which subsequently reacts to form COz and methyl radical oxidation products. As part of this work, a relative rate technique was used to measure the reactivity of C1 atoms toward C2HSC1, CD3CHzC1, and CHsCOCl. We report k(Cl+CZHsCl) = (8.7 f 1.0) X 10-l2, k(Cl+CD3CH2Cl) = (7.3 f 1.0) X 10-12 and k(Cl+CH3COCl) < 1 X lO-I4 (units of cm3 molecule-1 s-l). The implications of our results are discussed in terms of understanding the atmospheric chemistry of halogenated organic compounds.

Flash photolysis combined with time-resolved UV spectroscopy and transient I R absorption measurements shows that chlorine atoms react rapidly with CH3O2 and C2H502, producing C10 and C O among other products.The room temperature rate constants are kz = (1.5 f 0.2) X 1O-Io cm3 s-' for both reactions. The distribution of products is interpreted to indicate that the reaction with methylperoxy radicals proceeds via two channels to yield C H 3 0 + C10 with a branching ratio of 0.51 f 0.05 and CH2Oz + HCl with a branching ratio of 0.49 f 0.05. The Criegee intermediate, CH202, has a lifetime of 15 f 5 ps and subsequently decomposes via three channels, with 61 f 7% producing C O + H2O. The ethylperoxy reaction proceeds analogously with a branching fraction of 0.49 f 0.05 for the CzH50 + ClOchannel, but with a C O yield --'/aof the yield from themethylperoxy reaction.

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Collisional energy transfer parameters for highly vibrationally excited azulene have been deduced from new infrared fluorescence (lRF) emission lifetime data with an improved calibration relating IRF intensity to vibrational energy [. Phys. 78, 6695 ( 1983)] have been reanalyzed based on the improved calibration. Inversion of the IRF decay curves produced plots of energy decay, which were analyzed to determine (11E), the average energy transferred per collision. Master equation simulations reproduced both the original IRF decays and the deduced energy decays. A third (simple) method of (11E) determination agrees well with the other two. The results show (11E) to be nearly directly proportional to the vibrational energy of the excited azulene from -8000 to 33 000 cm -1. At high energies, there are indications that the (tJ.E) energy dependence may be slightly reduced.