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AGU: Geophysical Research Letters

 

Index Terms

  • Atmospheric Composition and Structure: Chemical kinetic and photochemical properties
  • Atmospheric Composition and Structure: Constituent sources and sinks
  • Atmospheric Composition and Structure: Middle atmosphere—composition and chemistry

Abstract

GEOPHYSICAL RESEARCH LETTERS, VOL. 29, 1299, 4 PP., 2002
doi:10.1029/2001GL014525

Kinetics of HO2 + HO2 → H2O2 + O2: Implications for Stratospheric H2O2

L. E. Christensen

Arthur Amos Noves Laboratory of Chemical Physics, Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, USA

M. Okumura

Arthur Amos Noves Laboratory of Chemical Physics, Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, USA

S. P. Sander

Jet Propulsion Laboratory, Pasadena, CA, USA

R. J. Salawitch

Jet Propulsion Laboratory, Pasadena, CA, USA

G. C. Toon

Jet Propulsion Laboratory, Pasadena, CA, USA

B. Sen

Jet Propulsion Laboratory, Pasadena, CA, USA

J.-F. Blavier

Jet Propulsion Laboratory, Pasadena, CA, USA

K. W. Jucks

Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, USA

The reaction HO2 + HO2 → H2O2 + O2(1) has been studied at 100 Torr and 222 K to 295 K. Experiments employing photolysis of Cl2/CH3OH/O2/N2 and F2/H2/O2/N2 gas mixtures to produce HO2 confirmed that methanol enhanced the observed reaction rate. At 100 Torr, zero methanol, k1 = (8.8 ± 0.9) 10−13 × exp[(210 ± 26)/T] cm3 molecule−1 s−1 (2σ uncertainties), which agrees with current recommendations at 295 K but is nearly 2 times slower at 231 K. The general expression for k1, which includes the dependence on bath gas density, is k1 = (1.5 ± 0.2) × 10−12 × exp[(19 ± 31)/T] + 1.7 × 10−33 × [M] × exp[1000/T], where the second term is taken from the JPL00-3 recommendation. The revised rate largely accounts for a discrepancy between modeled and measured [H2O2] in the lower to middle stratosphere.

Published 7 May 2002.

Citation: Christensen, L. E., M. Okumura, S. P. Sander, R. J. Salawitch, G. C. Toon, B. Sen, J.-F. Blavier, and K. W. Jucks (2002), Kinetics of HO2 + HO2 → H2O2 + O2: Implications for Stratospheric H2O2, Geophys. Res. Lett., 29(9), 1299, doi:10.1029/2001GL014525.

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