% IMPORTANT: The following is UTF-8 encoded.  This means that in the presence
% of non-ASCII characters, it will not work with BibTeX 0.99 or older.
% Instead, you should use an up-to-date BibTeX implementation like “bibtex8” or
% “biber”.

@ARTICLE{Schtze:841709,
      author       = {Schütze, Katharina and Wilson, James Charles and
                      Weinbruch, Stephan and Benker, Nathalie and Ebert, Martin
                      and Günther, Gebhard and Weigel, Ralf and Borrmann,
                      Stephan},
      title        = {{S}ub-micrometer refractory carbonaceous particles in the
                      polar stratosphere},
      journal      = {Atmospheric chemistry and physics},
      volume       = {17},
      number       = {20},
      issn         = {1680-7324},
      address      = {Katlenburg-Lindau},
      publisher    = {EGU},
      reportid     = {FZJ-2018-00017},
      pages        = {12475 - 12493},
      year         = {2017},
      abstract     = {Eleven particle samples collected in the polar stratosphere
                      during SOLVE (SAGE III Ozone loss and validation experiment)
                      from January until March 2000 were characterized in detail
                      by high-resolution transmission and scanning electron
                      microscopy (TEM/SEM) combined with energy-dispersive X-ray
                      microanalysis. A total of 4202 particles
                      (TEM  =  3872; SEM  =  330) were analyzed
                      from these samples, which were collected mostly inside the
                      polar vortex in the altitude range between 17.3 and
                      19.9 km. Particles that were volatile in the microscope
                      beams contained ammonium sulfates and hydrogen sulfates and
                      dominated the samples. Some particles with diameters ranging
                      from 20 to 830 nm were refractory in the electron beams.
                      Carbonaceous particles containing additional elements to C
                      and O comprised from 72 to $100 \%$ of the refractory
                      particles. The rest were internal mixtures of these
                      materials with sulfates. The median number mixing ratio of
                      the refractory particles, expressed in units of particles
                      per milligram of air, was 1.1 (mg air)−1 and varied
                      between 0.65 and 2.3 (mg air)−1.Most of the refractory
                      carbonaceous particles are completely amorphous, a few of
                      the particles are partly ordered with a graphene sheet
                      separation distance of 0.37 ± 0.06 nm (mean
                      value ± standard deviation). Carbon and oxygen are the
                      only detected major elements with an atomic O∕C ratio of
                      0.11 ± 0.07. Minor elements observed include Si, S, Fe,
                      Cr and Ni with the following atomic ratios relative to C:
                      Si∕C: 0.010 ± 0.011; S∕C: 0.0007 ± 0.0015;
                      Fe∕C: 0.0052 ± 0.0074; Cr∕C: 0.0012 ± 0.0017;
                      Ni∕C: 0.0006 ± 0.0011 (all mean
                      values ± standard deviation).High-resolution element
                      distribution images reveal that the minor elements are
                      distributed within the carbonaceous matrix; i.e.,
                      heterogeneous inclusions are not observed. No difference in
                      size, nanostructure and elemental composition was found
                      between particles collected inside and outside the polar
                      vortex.Based on chemistry and nanostructure, aircraft
                      exhaust, volcanic emissions and biomass burning can
                      certainly be excluded as sources. The same is true for the
                      less probable but globally important sources: wood burning,
                      coal burning, diesel engines and ship emissions.Recondensed
                      organic matter and extraterrestrial particles, potentially
                      originating from ablation and fragmentation, remain as
                      possible sources of the refractory carbonaceous particles
                      studied. However, additional work is required in order to
                      identify the sources unequivocally.},
      cin          = {IEK-7},
      ddc          = {550},
      cid          = {I:(DE-Juel1)IEK-7-20101013},
      pnm          = {244 - Composition and dynamics of the upper troposphere and
                      middle atmosphere (POF3-244)},
      pid          = {G:(DE-HGF)POF3-244},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000413242700002},
      doi          = {10.5194/acp-17-12475-2017},
      url          = {https://juser.fz-juelich.de/record/841709},
}