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| Titel |
Mass spectrometry of refractory black carbon particles from six sources: carbon-cluster and oxygenated ions |
| VerfasserIn |
J. C. Corbin, B. Sierau, M. Gysel, M. Laborde, A. Keller, J. Kim, A. Petzold, T. B. Onasch, U. Lohmann, A. A. Mensah |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 14, no. 5 ; Nr. 14, no. 5 (2014-03-13), S.2591-2603 |
| Datensatznummer |
250118479
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| Publikation (Nr.) |
 copernicus.org/acp-14-2591-2014.pdf |
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| Zusammenfassung |
We discuss the major mass spectral features of different types of
refractory carbonaceous particles, ionized after laser vaporization
with an Aerodyne high-resolution soot-particle aerosol mass
spectrometer (SP-AMS). The SP-AMS was operated with a switchable
1064 nm laser and a 600 °C thermal vaporizer,
yielding respective measurements of the refractory and
non-refractory particle components. Six samples were investigated,
all of which were composed primarily of refractory material:
fuel-rich and fuel-lean propane/air diffusion-flame combustion
particles; graphite-spark-generated particles; a commercial
fullerene-enriched soot; Regal Black, a commercial carbon black; and
nascent aircraft-turbine combustion particles.
All samples exhibited a spectrum of carbon-cluster ions
Cxn+ in their refractory mass spectrum. Smaller
clusters (x < 6) were found to dominate the Cxn+
distribution. For fullerene soot, fuel-rich-flame particles and
spark-generated particles, significant Cxn+ clusters at
x ≫ 6 were present, with significant contributions from
multiply charged ions (n > 1). In all six cases, the ions
C1+ and C3+ contributed over 60% to the
total C1+ intensity. Furthermore, the ratio of
these major ions C1+ / C3+ could be used to
predict whether significant Cxn+ signals with x > 5
were present. When such signals were present,
C1+ / C3+ was close to 1. When absent,
C1+ / C3+ was < 0.8. This ratio may therefore
serve as a proxy to distinguish between the two types of spectra in
atmospheric SP-AMS measurements.
Significant refractory oxygenated ions such as CO+ and
CO2+ were also observed for all samples. We discuss
these signals in detail for Regal Black, and describe their
formation via decomposition of oxygenated moieties incorporated into
the refractory carbon structure. These species may be of importance
in atmospheric processes such as water uptake and heterogeneous chemistry.
If atmospherically stable, these oxidized species may be useful for
distinguishing between different combustion sources. If unstable, they may
provide a means to estimate the atmospheric age of an rBC sample. Future
studies should attempt to establish which of these scenarios is more
realistic. |
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