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We use a combination of crossed laser-molecular beam scattering experiments and velocity map imaging experiments to investigate the three primary photodissociation channels of chloroacetone at 193 nm: C-Cl bond photofission yielding CH3C(O)CH2 radicals, C-C bond photofission yielding CH3CO and CH2Cl products, and C-CH3 bond photofission resulting in CH3 and C(O)CH2Cl products. Improved analysis of data previously reported by our group quantitatively identifies the contribution of this latter photodissociation channel. We introduce a forward convolution procedure to identify the portion of the signal, derived from the methyl image, which results from a two-step process in which C-Cl bond photofission is followed by the dissociation of the vibrationally excited CH3C(O)CH2 radicals to CH3 + COCH2. Subtracting this from the total methyl signal identifies the methyl photofragments that result from the CH3 + C(O)CH2Cl photofission channel. We find that about 89% of the chloroacetone molecules undergo C-Cl bond photofission to yield CH3C(O)CH2 and Cl products; approximately 8% result in C-C bond photofission to yield CH3CO and CH2Cl products, and the remaining 2.6% undergo C-CH3 bond photofission to yield CH3 and C(O)CH2Cl products. [ABSTRACT FROM AUTHOR]

The dissociation dynamics of methoxysulfinyl radicals generated from the photodissociation of CH3OS(O)Cl at 248 nm is investigated using both a crossed laser - molecular beam scattering apparatus and a velocity map imaging apparatus. There is evidence of only a single photodissociation channel of the precursor: S-Cl fission to produce Cl atoms and CH3OSO radicals. Some of the vibrationally excited CH3OSO radicals undergo subsequent dissociation to CH3 + SO2. The velocities of the detected CH3 and SO2 products show that the dissociation occurs via a transition state having a substantial barrier beyond the endoergicity; appropriately, the distribution of velocities imparted to these momentum-matched products is fit by a broad recoil kinetic energy distribution extending out to 24 kcal/mol in translational energy. Using 200 eV electron bombardment detection, we also detect the CH3OSO radicals that have too little internal energy to dissociate. These radicals are observed both at the parent CH3OSO+ ion as well as at the CH3+ and SO2+ daughter ions; they are distinguished by virtue of the velocity imparted in the original photolytic step. The detected velocities of the stable radicals are roughly consistent with the calculated barriers (both at the CCSD(T) and G3B3 levels of theory) for the dissociation of CH3OSO to CH3 + SO2 when we account for the partitioning of internal energy between rotation and vibration as the CH3OSOCl precursor dissociates. [ABSTRACT FROM AUTHOR]