Photodissociation of BrCH sub 2 CH sub 2 OH and ICH sub 2 CH sub 2 OH: Formation and characterization of OH( X sup 2. Pi. )

Journal Article · Tue Sep 01 04:00:00 EDT 1992 · Journal of Chemical Physics; (United States)

DOI:https://doi.org/10.1063/1.463000· OSTI ID:7273586

Sapers, S P; Hess, W P ^[1]

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1. Pacific Northwest Laboratory Richland, Washington 99352 (United States)

This work studies the dissociation of BrCH{sub 2}CH{sub 2}OH and ICH{sub 2}CH{sub 2}OH following laser excitation to the electronic {ital {tilde A}} state. The direct subpicosecond dissociation cleaves the {ital C}--{ital X} bond to produce CH{sub 2}CH{sub 2}OH and the halogen atom in either the ground ({sup 2}{ital P}{sub 3/2}) or excited ({sup 2}{ital P}{sub 1/2}) state. The initial dissociation produces excited CH{sub 2}CH{sub 2}OH in a distribution of internal states, some of which have sufficient energy to undergo secondary, {ital nonphotoinduced} dissociation to form OH and C{sub 2}H{sub 4}. We probe the OH translational and rotational product states following this secondary dissociation using laser-induced fluorescence in both flow cell and pulsed jet apparatus. Excitation of BrCH{sub 2}CH{sub 2}OH at 202 nm produces OH with no vibrational excitation and a non-Boltzmann rotational distribution with an average rotational energy of 8 kJ/mol. Doppler analysis of the rotational line shape shows that a majority of the energy available for the secondary dissociation is partitioned into relative translation of OH and C{sub 2}H{sub 4}. Excitation of ICH{sub 2}CH{sub 2}OH at 266 nm also produces OH, but at much lower quantum yields due to energetic constraints. We find that the CH{sub 2}CH{sub 2}OH radical also absorbs at 266 nm to produce OH. The rotational and translational energy distribution of OH from secondary dissociation of the CH{sub 2}CH{sub 2}OH radical is described qualitatively by a simple rotational model.

• DOE Contract Number: AC06-76RL01830
• OSTI ID: 7273586
• Journal Information: Journal of Chemical Physics; (United States), Journal Name: Journal of Chemical Physics; (United States) Vol. 97:5; ISSN JCPSA; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500* -- Photochemistry
ALKENES
CHEMICAL REACTIONS
DECOMPOSITION
DOPPLER EFFECT
ELECTROMAGNETIC RADIATION
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
ETHYLENE
EXCITATION
EXCITED STATES
HYDROCARBONS
HYDROXYL RADICALS
LASER RADIATION
ORGANIC BROMINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC IODINE COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
PRODUCTION
RADIATIONS
RADICALS
ROTATIONAL STATES
ULTRAVIOLET RADIATION