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Etudes cinétiques et mécanistiques des processus d'oxydation des composés organiques volatils d'importance atmosphérique induits par le radical nitrate en atmosphères simulées.

Abstract : To study the chemical transformations of volatile organic compounds in the atmosphere, the physico-chemist requires some results that can be easily interpreted and, on the other hand, that can be extrapolated to the atmospheric conditions. These constraints imply the variability and complexity of the atmosphere needs to be simplified in laboratory experiments while keeping experimental conditions as close as possible of the atmospheric ranges of pressure, temperature and concentrations. This can be achieved by performing « simulation experiments ». During this doctoral work, atmospheric simulation methods have been used within the study of the reactivity of the nitrate radical toward volatile organic compounds of tropospheric interest. This approach led us to the development of a simulation chamber. We have chosen to use long path UV-visible spectrometry and very long path FT-IR spectrometry as analytical methods. In order to improve this methods we have built up a new type of infrared multi-reflection stabilised cell. Our results concern the study of the nitrate radical initiated oxidation mechanisms of acetaldehyde, propionaldehyde, benzene and toluene. Our results have allowed us to describe completely the aldehyde oxidation scheme and to determinate associated rate constants. Ours experiments have confirmed the existence of reactions between nitrate radicals and peroxyacyl radicals. These reactions have been studied under simulated atmospheric conditions. The discussion of these results shows that this process could be significant in the troposphere. We have shown that the reactions of NO3 with secondary radicals are of great importance in the simulation experiments. The nitrate radical is one of the major species of the night-time troposphere so our results are of importance for the understanding of the atmospheric transformations of pollutants at night. Our research shows that mechanistic studies with complete mass balance can be achieved by the use of a simulation chamber together with powerful spectrometric methods. Moreover, understanding of the generation and the evolution of intermediate radical species can be reached.
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https://tel.archives-ouvertes.fr/tel-00002792
Contributor : Jean-Francois Doussin <>
Submitted on : Monday, May 5, 2003 - 12:32:18 PM
Last modification on : Friday, April 10, 2020 - 5:30:02 PM
Long-term archiving on: : Friday, April 2, 2010 - 7:03:22 PM

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  • HAL Id : tel-00002792, version 1

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Jean-Francois Doussin. Etudes cinétiques et mécanistiques des processus d'oxydation des composés organiques volatils d'importance atmosphérique induits par le radical nitrate en atmosphères simulées.. Autre. Université Paris-Diderot - Paris VII, 1998. Français. ⟨tel-00002792⟩

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