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Time-Resolved O3 Chemical Chain Reaction Kinetics Via High-Resolution IR Laser Absorption MethodsExcimer laser photolysis in combination with time-resolved IR laser absorption detection of OH radicals has been used to study O3/OH(v = 0)/HO2 chain reaction kinetics at 298 K, (i.e.,(k(sub 1) is OH + 03 yields H02 + 02 and (k(sub 2) is H02 + 03 yields OH + 202). From time-resolved detection of OH radicals with high-resolution near IR laser absorption methods, the chain induction kinetics have been measured at up to an order of magnitude higher ozone concentrations ([03] less than or equal to 10(exp 17) molecules/cu cm) than accessible in previous studies. This greater dynamic range permits the full evolution of the chain induction, propagation, and termination process to be temporally isolated and measured in real time. An exact solution for time-dependent OH evolution under pseudo- first-order chain reaction conditions is presented, which correctly predicts new kinetic signatures not included in previous OH + 03 kinetic analyses. Specifically, the solutions predict an initial exponential loss (chain "induction") of the OH radical to a steady-state level ([OH](sub ss)), with this fast initial decay determined by the sum of both chain rate constants, k(sub ind) = k(sub 1) + k(sub 2). By monitoring the chain induction feature, this sum of the rate constants is determined to be k(sub ind) = 8.4(8) x 10(exp -14) cu cm/molecule/s for room temperature reagents. This is significantly higher than the values currently recommended for use in atmospheric models, but in excellent agreement with previous results from Ravishankara et al.
Document ID
19990017750
Acquisition Source
Headquarters
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Kulcke, Axel
(Optima Handels G.m.b.H. Austria)
Blackmon, Brad
(Colorado Univ. Boulder, CO United States)
Chapman, William B.
(Colorado Univ. Boulder, CO United States)
Kim, In Koo
(Colorado Univ. Boulder, CO United States)
Nesbitt, David J.
(Colorado Univ. Boulder, CO United States)
Date Acquired
August 19, 2013
Publication Date
January 1, 1998
Publication Information
Publication: Journal of Physical Chemistry A
Publisher: American Chemical Society
Volume: 102
Issue: 11
Subject Category
Inorganic And Physical Chemistry
Distribution Limits
Public
Copyright
Other

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