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Photochemical Studies in Flash Photolysis. III. Photolysis of Acetone in Different Wavelength Regions

Shilman, A. and Marcus, R. A. (1963) Photochemical Studies in Flash Photolysis. III. Photolysis of Acetone in Different Wavelength Regions. Journal of Chemical Physics, 39 (4). pp. 996-1003. ISSN 0021-9606. doi:10.1063/1.1734403.

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The flash photolysis of acetone was studied at wavelength regions centered around 260, 280, and 300 mμ, using absorbed intensities of the order of 10^(19) quanta/cc/sec for each wavelength region. The light source was an exploding wire, and the maximum temperature increase per flash was calculated to be not more than 5°C. The products, analyzed by gas chromatography using a sensitive electric discharge detector, consisted of C_2H_6, CO, biacetyl, and, in smaller amounts, CH_4. A search was made for other products as well, and detection limits are given. The C_2H_6/CO ratio decreased with increasing acetone pressure at all wavelength regions and was independent of light intensity in the range investigated. The R_(CO)/p_(acet) ratio, measured over a wide pressure range, was pressure‐independent at 260 and 300 mμ but increased appreciably with pressure at 280 mμ. At low pressures, where the C_2H_6/CO ratio approached a limiting value, the ratio decreased with wavelength according to the order 280>260>300 mμ. The lifetime of the excited acetone molecules at the respective wavelengths was estimated, from a steady‐state treatment, to be 0.6×10^(—9), 1×10^(—9), and 4×10^(—9) sec at 260, 280, and 300 mμ, assuming a collision deactivation efficiency of unity. At 300 mμ there was a marked difference in value of C_2H_6/CO at flash and low intensities: certain second‐order reactions involving excited states appear to occur completely at the relatively high concentrations prevailing under flash conditions. The transition region of intensity effects is described in subsequent papers of this series.

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Marcus, R. A.0000-0001-6547-1469
Additional Information:© 1963 American Institute of Physics. Received 29 June 1962. Online Publication Date: 29 June 2004. Abstracted in part from the doctoral dissertation of Avner Shilman, Polytechnic Institute of Brooklyn, June 1961. (Available on microfilm from University Microfilms, Ann Arbor, Michigan.) This work was supported by the Directorate of Chemical Sciences, Air Force Office of Scientific Research. Alfred P. Sloan Fellow.
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Air Force Office of Scientific ResearchUNSPECIFIED
Alfred P. Sloan fellowshipUNSPECIFIED
Issue or Number:4
Record Number:CaltechAUTHORS:20120829-143226417
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Official Citation:Photochemical Studies in Flash Photolysis. III. Photolysis of Acetone in Different Wavelength Regions A. Shilman and R. A. Marcus J. Chem. Phys. 39, 996 (1963);
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ID Code:33680
Deposited By: Ruth Sustaita
Deposited On:29 Aug 2012 22:23
Last Modified:09 Nov 2021 21:36

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