Analyzing velocity map images to distinguish the primary methyl photofragments from those produced upon C-Cl bond photofission in chloroacetone at 193 nm

Journal Article · Thu Jul 21 04:00:00 EDT 2011 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.3609757· OSTI ID:22038646

Alligood, Bridget W; Straus, Daniel B; Butler, Laurie J ^[1]

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1. James Franck Institute and Department of Chemistry, University of Chicago, Chicago, Illinois 60637 (United States)

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 CH{sub 3}C(O)CH{sub 2} radicals, C-C bond photofission yielding CH{sub 3}CO and CH{sub 2}Cl products, and C-CH{sub 3} bond photofission resulting in CH{sub 3} and C(O)CH{sub 2}Cl 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 CH{sub 3}C(O)CH{sub 2} radicals to CH{sub 3}+ COCH{sub 2}. Subtracting this from the total methyl signal identifies the methyl photofragments that result from the CH{sub 3}+ C(O)CH{sub 2}Cl photofission channel. We find that about 89% of the chloroacetone molecules undergo C-Cl bond photofission to yield CH{sub 3}C(O)CH{sub 2} and Cl products; approximately 8% result in C-C bond photofission to yield CH{sub 3}CO and CH{sub 2}Cl products, and the remaining 2.6% undergo C-CH{sub 3} bond photofission to yield CH{sub 3} and C(O)CH{sub 2}Cl products.

• OSTI ID: 22038646
• Journal Information: Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 3 Vol. 135; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
74 ATOMIC AND MOLECULAR PHYSICS
CARBON COMPOUNDS
DISSOCIATION
MOLECULAR BEAMS
MULTI-PHOTON PROCESSES
ORGANIC COMPOUNDS
PHOTOFISSION
PHOTOLYSIS
PHOTON-MOLECULE COLLISIONS
VIBRATIONAL STATES