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Temperature Dependence of the HO_2 + ClO Reaction. 1. Reaction Kinetics by Pulsed Photolysis-Ultraviolet Absorption and ab Initio Studies of the Potential Surface

Nickolaisen, Scott L. and Roehl, Coleen M. and Blakeley, Lisa K. and Friedl, Randall R. and Francisco, Joseph S. and Liu, Ruifeng and Sander, Stanley P. (2000) Temperature Dependence of the HO_2 + ClO Reaction. 1. Reaction Kinetics by Pulsed Photolysis-Ultraviolet Absorption and ab Initio Studies of the Potential Surface. Journal of Physical Chemistry A, 104 (2). pp. 308-319. ISSN 1089-5639. https://resolver.caltech.edu/CaltechAUTHORS:20170316-161356188

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Abstract

The kinetics of the HO_2 + ClO reaction was studied using the flash photolysis/ultraviolet absorption technique over the temperature range 203−364 K and pressure range 50−700 Torr of N_2. In contrast to previous work, the temperature dependence displayed linear Arrhenius behavior over the entire temperature range with the rate constant being described by the expression k(T) = 2.84 × 10^(-12) exp{(312 ± 60)/T} cm^3 molecule^(-1) s^(-1). Ab initio calculations of intermediates and transition states have been carried out on the singlet and triplet potential energy surfaces. These calculations show that the reaction proceeds mainly through the ClO−HO_2 complex on the triplet surface; however, collisionally stabilized HOOOCl formed on the singlet surface will possess an appreciable lifetime due to large barriers toward decomposition to HCl and HOCl. Termolecular rate calculations using ab initio parameters lead to a strong collision rate constant of ∼5 × 10^(-32) cm^6 molecule^(-2) s^(-1) for HOOOCl formation. This intermediate may be important under both laboratory and atmospheric conditions.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://dx.doi.org/10.1021/jp992753hDOIArticle
http://pubs.acs.org/doi/abs/10.1021/jp992753hPublisherArticle
ORCID:
AuthorORCID
Roehl, Coleen M.0000-0001-5383-8462
Sander, Stanley P.0000-0003-1424-3620
Additional Information:© 2000 American Chemical Society. Received: August 4, 1999; In Final Form: October 29, 1999. Publication Date (Web): December 16, 1999. We acknowledge the expert technical assistance of Mr. Dave Natzic in the setup and execution of these experiments. We have benefited greatly from frequent discussions with Dr. M. Okumura (Caltech), Dr. R. Salawitch, and members of the JPL Chemical Kinetics and Photochemistry Group. Support for L. Blakeley was provided under an NIH Minority Access to Research Careers (MARC) Grant, no. GM08228. The supercomputer used in this investigation was provided by funding from the NASA Offices of Earth Science, Aeronautics and Space Science. The research was carried out by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.
Funders:
Funding AgencyGrant Number
NIHGM08228
NASA/JPL/CaltechUNSPECIFIED
Issue or Number:2
Record Number:CaltechAUTHORS:20170316-161356188
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20170316-161356188
Official Citation:Temperature Dependence of the HO2 + ClO Reaction. 1. Reaction Kinetics by Pulsed Photolysis-Ultraviolet Absorption and ab Initio Studies of the Potential Surface Scott L. Nickolaisen, Coleen M. Roehl, Lisa K. Blakeley, Randall R. Friedl, Joseph S. Francisco, Ruifeng Liu, and Stanley P. Sander The Journal of Physical Chemistry A 2000 104 (2), 308-319 DOI: 10.1021/jp992753h
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:75190
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:17 Mar 2017 15:05
Last Modified:03 Oct 2019 16:47

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