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@PHDTHESIS{RodriguezBares:31594,
      author       = {Rodriguez Bares, Sonia},
      title        = {{U}ntersuchungen zur {O}zonolyse einfacher {A}lkene in der
                      {A}tmosphären-{S}imulationskammer {SAPHIR}},
      volume       = {4040},
      issn         = {0944-2952},
      school       = {Univ. Köln},
      type         = {Dr. (Univ.)},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich Jülich GmbH Zentralbibliothek,
                      Verlag},
      reportid     = {PreJuSER-31594, Juel-4040},
      series       = {Berichte des Forschungszentrums Jülich},
      pages        = {XII, 193 p.},
      year         = {2003},
      note         = {Record converted from VDB: 12.11.2012; Köln, Univ., Diss.,
                      2003},
      abstract     = {The ozonolysis, that is, the oxidation with O$_{3}$, is one
                      of the most important removal pathways for alkenes in the
                      troposphere. The ozonolysis competes with the removal of
                      alkenes through the reaction with OH-radicals during the day
                      and through the reaction with NO$_{3}$ during the night. The
                      mechanism of the gas-phase ozonolysis is as yet not fully
                      understood. It is suspected that during ozonolysis beside
                      different stable products OH and HO$_{2}$ radicals are also
                      formed, which play an important role in the tropospheric
                      chemistry. The scope of this work was to find an answer to
                      this and other questions related to the ozonolysis and to
                      discuss their relevance within the tropospheric chemistry.
                      Short chained alkenes (C$_{n}$ with n < 5) are the main
                      components of the total alkenes in urban regions. Past
                      investigations were carried out with reactant concentrations
                      within the ppmv range. These values are clearly much higher
                      than the concentrations found in the troposphere. The
                      question arises wether the observations at high
                      concentrations would apply to the lower tropospheric ppbv
                      range. Within the scope of this work the ozonolysis of
                      C$_{2}$ to C$_{4}$ alkenes with reactant concentrations
                      between 20 ppbv and 200 ppbv were investigated. The
                      atmospheric simulation chamber SAPHIR in the Research Center
                      in Jülich, Germany, was used for this purpose. Experiments
                      with CO as radical scavenger were carried out to determine
                      the rate constants of the ozonolysis of the investigated
                      alkenes. The results fell within the range presented in the
                      literatur. The time profile of the ozonolysis reactions were
                      in excellent agreement with the expected kinetics, which
                      cancels the likelihood of any interfering chemical
                      processes. The yields for OH and HO$_{2}$ radicals of the
                      investigated alkenes was determined. The yield of OH
                      obtained illustrated a water dependence not previously
                      mentioned in literatur. This work produced also the first
                      determinations for the HO$_{2}$ yields, which exceeded a
                      value of 1.0 for the most alkenes, contradicting an assumed
                      value of 0.2 used in models. In addition the yields of
                      stable products such as HCHO, CH$_{3}$CHO and CO were also
                      determined. With Z-2-Buten a water dependence of the
                      CH$_{3}$CHO yield was also found. For some alkenes the
                      obtained yields of HCHO and CH$_{3}$CHO were greater than
                      found in previous experimental determinations. This clearly
                      points to additional unidentified reactions pathways leading
                      to HCHO and CH$_{3}$CHO. What was also proven was a CO
                      dependence of the yields of HO$_{2}$ and CH$_{3}$CHO. In
                      order to explain the former observations the standard
                      mechanism of the ozonolysis was modified. This modification
                      takes into consideration the competition between the
                      unimolecular decomposition of two different Criegee
                      Intermediates and their bimolecular reaction with either
                      water or CO. The water dependence of the OH yield would lead
                      to a lower OH concentration at night in dry regions as
                      compared to humid regions and consequently to a lower
                      overall removal of hydrocarbons. The importance of the
                      higher yields for HO$_{2}$ radicals was investigated using a
                      box model. The simulation showed for the first time that
                      higher HO$_{2}$ yields lead to higher HO$_{2}$
                      concentrations at night. The recombination of the HO$_{2}$
                      radicals and/or reactions with other peroxiradicals thus
                      result in higher H$_{2}$O$_{2}$ concentrations as well as
                      higher concentrations of organic peroxides than expected.},
      cin          = {ICG-II},
      cid          = {I:(DE-Juel1)VDB48},
      pnm          = {Chemie und Dynamik der Geo-Biosphäre},
      pid          = {G:(DE-Juel1)FUEK257},
      typ          = {PUB:(DE-HGF)11 / PUB:(DE-HGF)3},
      url          = {https://juser.fz-juelich.de/record/31594},
}