Probing the O( sup 1 D )+CO sub 2 reaction with second-derivative modulated diode laser spectroscopy
- Department of Chemistry, Brookhaven National Laboratory, Upton, New York 11973 (US)
- Department of Chemistry and Columbia Radiation Laboratory, Columbia University, New York, New York 10027 (US)
The reaction of electronically excited O({sup 1}{ital D}) atoms with CO{sub 2} to form CO+O{sub 2}({sup 1}{Sigma}{sup +}{sub {ital g}},{sup 1}{Delta}{sub {ital g}},{sup 3}{Sigma}{sup {minus}}{sub {ital g}}) has been probed with second-derivative modulated diode laser spectroscopy. The O({sup 1}{ital D}) atoms were generated by the pulsed 193 nm laser photolysis of N{sub 2}O, and the reaction was followed by monitoring the formation of CO as a function of the number of laser pulses. These experiments have revealed that the quantum yield for this reaction is (2.1{plus minus}0.3){times}10{sup {minus}3} molecules/photon absorbed. The very low quantum efficiency suggests that a significant potential barrier exists on the reaction coordinate which prevents the vast majority of collisions from fragmenting into products distinguishable from reactants. The rate constant, measured indirectly by comparison with the rate constant for quenching, is found to be (2.4{plus minus}0.5){times}10{sup {minus}13} cm{sup 3} molecule{sup {minus}1} s{sup {minus}1} and represents the best estimate currently available in the literature for the reaction rate constant. In experiments involving {sup 16}O({sup 1}{ital D})+{sup 12}C{sup 18}O{sub 2}, the resulting product, {sup 12}C{sup 18}O, indicates that no isotopic exchange takes place in the reaction. Comparison with deactivation results suggests that the reaction proceeds by a simple, direct oxygen-atom abstraction with a potential barrier, whereas the quenching channel involves a long-lived intermediate.
- OSTI ID:
- 5040616
- Journal Information:
- Journal of Chemical Physics; (USA), Vol. 91:12; ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
CARBON DIOXIDE
CHEMICAL REACTION KINETICS
CARBON MONOXIDE
CHEMICAL REACTION YIELD
NITROUS OXIDE
PHOTOLYSIS
OXYGEN
FAR ULTRAVIOLET RADIATION
INFRARED SPECTRA
LASER RADIATION
LASER SPECTROSCOPY
MONITORING
QUANTUM EFFICIENCY
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
DECOMPOSITION
EFFICIENCY
ELECTROMAGNETIC RADIATION
ELEMENTS
KINETICS
NITROGEN COMPOUNDS
NITROGEN OXIDES
NONMETALS
OXIDES
OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
RADIATIONS
REACTION KINETICS
SPECTRA
SPECTROSCOPY
ULTRAVIOLET RADIATION
YIELDS
400201* - Chemical & Physicochemical Properties