Photofragmentation of acetone at 193 nm: rotational- and vibrational-state distributions of the CO fragment by time-resolved FTIR emission spectroscopy

Journal Article · Thu Sep 22 04:00:00 EDT 1988 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j100330a014· OSTI ID:6254086

Woodbridge, E L; Fletcher, T R; Leone, S R

Photofragmentation of acetone at 193 nm is known to produce predominantly two methyl radicals and a CO molecule. Infrared emission is collected for the CO fragment at time delays of 6-30 ..mu..s after the exciting laser pulse by a time-resolved Fourier transform spectrometer. High-resolution vibration-rotation spectra are obtained both under collision-free and rotationally relaxed conditions. The observed vibrational distribution is, for v = 1/2/3, 0.73 /plus minus/ 0.04/0.23 /plus minus/ 0.02/0.04 /plus minus/ 0.01. This distribution fits a temperature of /approximately/ 2030/sub /minus/430//sup +730/ K, in approximate agreement with previous low-resolution results from this laboratory. The observed rotational distribution is highly excited, approximating a temperature of 3360/sub /minus/800//sup +1540/ K. Both the vibrational and rotational distributions can be successfully modeled by using a pure impulsive mechanism for the fragmentation of an initial bent acetyl fragment. Thus, the observed distribution supports previous arguments that the dissociation occurs by a two-step fragmentation mechanism following single-photon excitation.

• Research Organization: National Bureau of Standards, Boulder, CO (USA)
• OSTI ID: 6254086
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 92:19; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500* -- Photochemistry
ACETONE
ALKYL RADICALS
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
DATA
DECOMPOSITION
EMISSION SPECTROSCOPY
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EXCITED STATES
EXPERIMENTAL DATA
FOURIER TRANSFORM SPECTROMETERS
INFORMATION
INFRARED SPECTRA
KETONES
LASERS
MEASURING INSTRUMENTS
METHYL RADICALS
NUMERICAL DATA
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
RADICALS
ROTATIONAL STATES
SPECTRA
SPECTROMETERS
SPECTROSCOPY
VIBRATIONAL STATES