Temperature Dependence of the HO2 + ClO Reaction. 1. Reaction Kinetics by Pulsed Photolysis-Ultraviolet Absorption and ab Initio Studies of the Potential Surface
Document Type
Article
Publication Date
1-20-2000
Description
The kinetics of the HO2 + 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 N2. 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} cm3 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-HO2 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 cm6 molecule-2 s-1 for HOOOCl formation. This intermediate may be important under both laboratory and atmospheric conditions.
Citation Information
Nickolaisen, Scott L.; Roehl, Coleen M.; Blakeley, Lisa K.; Friedl, Randall R.; Francisco, Joseph S.; Liu, Ruifeng; and Sander, Stanley P.. 2000. Temperature Dependence of the HO2 + ClO Reaction. 1. Reaction Kinetics by Pulsed Photolysis-Ultraviolet Absorption and ab Initio Studies of the Potential Surface. Journal of Physical Chemistry A. Vol.104(2). 308-319. https://doi.org/10.1021/jp992753h ISSN: 1089-5639