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@PHDTHESIS{Pullinen:811725,
      author       = {Pullinen, Laura Iida Maria},
      title        = {{P}hotochemistry of {H}ighly {O}xidized {M}ultifunctional
                      {O}rganic {M}olecules: a {C}hamber {S}tudy},
      volume       = {387},
      school       = {Universität Köln},
      type         = {Dissertation},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
      reportid     = {FZJ-2016-04109},
      isbn         = {978-3-95806-260-3},
      series       = {Schriften des Forschungszentrums Jülich Reihe Energie $\&$
                      Umwelt / Energy $\&$ Environment},
      pages        = {II, 96, xvii S.},
      year         = {2017},
      note         = {Universität Köln, Diss., 2016},
      abstract     = {Highly oxidized multifunctional organic molecules (HOMs)
                      are a newly-found class of compounds that are formed in
                      volatile organic compound (VOC) oxidation. Due to high O:C
                      ratios of the HOMs, they are suggested to participate in
                      atmospheric processes, such as new particle formation (NPF)
                      and particle mass formation. Thus studying HOMs gives
                      important insight into mechanisms of particle formation and
                      growth under different chemistry regimes. OH is the main
                      oxidant during daytime chemistry, however so far the
                      photochemical HOM formation has not been studied in detail.
                      This study focusses on the photochemical HOM production
                      from-pinene, on chemical transformation of HOMs as well as
                      on their loss processes. Autoxidation was found to be a
                      dominant process of photochemical HOM formation. However,
                      comparison of the photochemical HOM patterns from
                      $\alpha$-pinene and its main primary oxidation product
                      pinonaldehyde showed that also secondary OH oxidation is
                      likely to contribute to some extent. In one experiment the
                      oxygen content of the chamber during the experiment was
                      lowered below 1\% and the HOM formation was not affected,
                      which indicates that autoxidation must be very fast. OH
                      oxidation of pinonaldehyde, $\beta$-pinene, cyclohexene,
                      benzene, and methyl salicylate led to HOM formation. If at
                      all, these compounds do not react efficiently with ozone,
                      suggesting that photooxidation might be a source of HOMs in
                      general. The effect of photochemistry on HOM formation from
                      $\alpha$-pinene was studied in more detail. The yield of
                      HOMs from $\alpha$-pinene photooxidation was found to depend
                      on [OH] and estimated to be between 1.8 and 7\%. Adding
                      NO$_{x}$ led to the formation of organic nitrates as well as
                      to a general increase of HOM formation. The formation of
                      organic nitrates confirmed the assignment of HOMs being
                      peroxy radicals. The general increase of HOM formation
                      observed up to moderate NO$_{x}$ levels was mainly due to OH
                      recycling by HO$_{2}$ + NO reactions leading to increased
                      [OH]. Additionally, the presence of NO$_{x}$ also activated
                      the “alkoxy-peroxy pathway”. Alkoxy radicals formed in
                      reactions of NO with peroxy radicals might undergo internal
                      H-shifts and subsequent O$_{2}$ additions, instead of
                      degrading. This pathway can form peroxy radicals and explain
                      why even at very high [NO$_{x}$] there were still
                      termination products of RO$_{2}$ + RO$_{2}$ reactions
                      observable. High [HO$_{2}$] favoured hydroperoxide formation
                      and diminished formation of other termination products.
                      Altogether, the behaviour of HOMs was compatible to
                      classical models of peroxy radical chemistry. Effective
                      uptake coefficients for HOMs on particles were determined to
                      be in the range of 0.5-0.9 for monomers and unity for
                      dimers. At mass loads above ~ 3 $\mu$g m$^{-3}$ impacts of
                      particles on peroxy radical chemistry became obvious
                      suggesting an impact of particles on photochemistry also
                      under atmospheric conditions.},
      cin          = {IEK-8},
      cid          = {I:(DE-Juel1)IEK-8-20101013},
      pnm          = {243 - Tropospheric trace substances and their
                      transformation processes (POF3-243) / HITEC - Helmholtz
                      Interdisciplinary Doctoral Training in Energy and Climate
                      Research (HITEC) (HITEC-20170406)},
      pid          = {G:(DE-HGF)POF3-243 / G:(DE-Juel1)HITEC-20170406},
      typ          = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
      urn          = {urn:nbn:de:0001-2017121314},
      url          = {https://juser.fz-juelich.de/record/811725},
}