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@ARTICLE{Ehn:22984,
      author       = {Ehn, M. and Kleist, E. and Junninen, H. and Petäjä, T.
                      and Lönn, G. and Schobesberger, S. and Dal Maso, M. and
                      Trimborn, A. and Kulmala, M. and Worsnop, D. and Wahner, A.
                      and Wildt, J. and Mentel, Th.F.},
      title        = {{G}as phase formation of extremely oxidized pinene reaction
                      products in chamber and ambient air},
      journal      = {Atmospheric chemistry and physics},
      volume       = {12},
      issn         = {1680-7316},
      address      = {Katlenburg-Lindau},
      publisher    = {EGU},
      reportid     = {PreJuSER-22984},
      pages        = {5113 - 5127},
      year         = {2012},
      note         = {M. E. gratefully acknowledges financial support by the Emil
                      Aaltonen foundation. This work was supported by the ERC
                      Advanced Grant EU-FP7-ATMNUCLE (project no 227463), and by
                      the Academy of Finland Center of Excellence program (project
                      no 1118615).},
      abstract     = {High molecular weight (300-650 Da) naturally charged
                      negative ions have previously been observed at a boreal
                      forest site in Hyytiala, Finland. The long-term measurements
                      conducted in this work showed that these ions are observed
                      practically every night between spring and autumn in
                      Hyytiala. The ambient mass spectral patterns could be
                      reproduced in striking detail during additional measurements
                      of alpha-pinene (C10H16) oxidation at low-OH conditions in
                      the Julich Plant Atmosphere Chamber (JPAC). The ions were
                      identified as clusters of the nitrate ion (NO3-) and
                      alpha-pinene oxidation products reaching oxygen to carbon
                      ratios of 0.7-1.3, while retaining most of the initial ten
                      carbon atoms. Attributing the ions to clusters instead of
                      single molecules was based on additional observations of the
                      same extremely oxidized organics in clusters with HSO4-
                      (Hyytiala) and C3F5O2- (JPAC). The most abundant products in
                      the ion spectra were identified as C10H14O7, C10H14O9,
                      C10H16O9, and C10H14O11. The mechanism responsible for
                      forming these molecules is still not clear, but the initial
                      reaction is most likely ozone attack at the double bond, as
                      the ions are mainly observed under dark conditions.
                      beta-pinene also formed highly oxidized products under the
                      same conditions, but less efficiently, and mainly C-9
                      compounds which were not observed in Hyytiala, where
                      beta-pinene on average is 4-5 times less abundant than
                      alpha-pinene. Further, to explain the high O/C together with
                      the relatively high H/C, we propose that geminal diols
                      and/or hydroperoxide groups may be important. We estimate
                      that the night-time concentration of the sum of the neutral
                      extremely oxidized products is on the order of 0.1-1 ppt
                      (similar to 10(6)-10(7) molec cm(-3)). This is in a similar
                      range as the amount of gaseous H2SO4 in Hyytiala during
                      day-time. As these highly oxidized organics are roughly 3
                      times heavier, likely with extremely low vapor pressures,
                      their role in the initial steps of new aerosol particle
                      formation and growth may be important and needs to be
                      explored in more detail in the future.},
      keywords     = {J (WoSType)},
      cin          = {IEK-8 / IBG-2},
      ddc          = {550},
      cid          = {I:(DE-Juel1)IEK-8-20101013 / I:(DE-Juel1)IBG-2-20101118},
      pnm          = {Atmosphäre und Klima},
      pid          = {G:(DE-Juel1)FUEK491},
      shelfmark    = {Meteorology $\&$ Atmospheric Sciences},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000305281600020},
      doi          = {10.5194/acp-12-5113-2012},
      url          = {https://juser.fz-juelich.de/record/22984},
}