Russian Journal of Physical Chemistry B

, Volume 6, Issue 4, pp 471–474 | Cite as

A study of the temperature dependence of the rate constant for the reaction of O2 with surface alkoxy radicals

  • A. V. StepanovEmail author
  • D. V. Shestakov
Kinetics and Mechanism of Chemical Reactions. Catalysis


A method for studying the reactions of surface alkoxy radicals with O2 at temperatures of 230 to 300 K is described. Alkoxy radicals were generated directly in the cavity of an EPR spectrometer. Surface organic radicals, prepared from paraffin wax ((CH3)2(CH2) n , n = 16–20), were applied to Aerosil particles from a solution in heptane. The Aerosil sample was placed in the cavity of the EPR spectrometer in a cylindrical cup with a central hole for pumping out gases and exposed to H atoms. In this way, it is possible observe a steady increase in the EPR signal from the surface radicals. To measure the rate constant at tropospheric temperatures, the reaction tube was placed in a Teflon jacket, through which cool nitrogen vapor was pumped. The temperature in the reactor was varied from 230 to 300 K. The recorded EPR spectra belong to the (RO) s radical. After obtaining a stable EPR signal from the surface radicals, treatment with H atoms was stopped, additional flow of O2 was introduced ([O2] = 1014–1016 cm−3), and the reaction of O2 with the surface organic radicals was studied by monitoring the EPR signal decay. The temperature dependence of the rate constant for the (RO) s + O2 → HO2 + ketone was obtained within T = 230–300 K. The extrapolation of the data to real tropospheric conditions ([O2] = 1018 cm−3) was performed.


oxidation of organic aerosols surface organic radicals EPR spectroscopy 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    J. H. Seinfeld and S. N. Pandis, Atmospheric Chemistry and Physics (Willey, New York, 1997).Google Scholar
  2. 2.
    S. Fuzzi, S. Decesari, M. C. Facchini, M. Mircea, E. Matta, and E. Tagliavini, in Proceedings of the Eurotrac-2 Symposium, Garmisch-Partenkirchen, Germany, 2002 (Margraf, Weikersheim, 2002), PRO-3.Google Scholar
  3. 3.
    V. A. Isidorov, Organic Chemistry of Atmosphere (Khimizdat, St. Petersburg, 2001) [in Russian].Google Scholar
  4. 4.
    J. I. Balkanski, D. J. Jacob, and G. M. Gardner, J. Geophys. Res. 98, 20573 (1993).CrossRefGoogle Scholar
  5. 5.
    T. Moise and Yi. Rudich, Geophys. Rev. Lett. 28, 4083 (2001).CrossRefGoogle Scholar
  6. 6.
    A. K. Bertram, A. V. Ivanov, M. Hunter, L. T. Molina, and M. J. Molina, J. Phys. Chem. A 105, 9415 (2001).CrossRefGoogle Scholar
  7. 7.
    A. V. Stepanov, D. V. Shestakov, R. G. Remorov, et al., Khim. Fiz. 23(12), 46 (2004).Google Scholar
  8. 8.
    M. J. Molina, A. V. Ivanov, S. Trakhtenberg, and L. T. Molina, Geophys. Rev. Lett. 31, L22104 (2004).CrossRefGoogle Scholar
  9. 9.
    A. V. Stepanov, S. S. Kimmel’fel’d, D. V. Shestakov, S.D. Il’in, V. V. Zelenev, and Yu. M. Gershenzon, Khim. Fiz. 25(5), 25 (2006).Google Scholar
  10. 10.
    A. V. Ivanov, A. Yu. Zasypkin, A. V. Stepanov, and Yu.M. Gershenzon, Khim. Fiz. 27(4), 11 (2008).Google Scholar

Copyright information

© Pleiades Publishing, Ltd. 2012

Authors and Affiliations

  1. 1.Semenov Institute of Chemical PhysicsRussian Academy of SciencesMoscowRussia

Personalised recommendations