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| Titel |
Collection efficiency of the soot-particle aerosol mass spectrometer (SP-AMS) for internally mixed particulate black carbon |
| VerfasserIn |
M. D. Willis, A. K. Y. Lee, T. B. Onasch, E. C. Fortner, L. R. Williams, A. T. Lambe, D. R. Worsnop, J. P. D. Abbatt |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1867-1381
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 7, no. 12 ; Nr. 7, no. 12 (2014-12-18), S.4507-4516 |
| Datensatznummer |
250115999
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| Publikation (Nr.) |
 copernicus.org/amt-7-4507-2014.pdf |
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| Zusammenfassung |
| The soot-particle aerosol mass spectrometer (SP-AMS) uses an
intra-cavity infrared laser to vaporize refractory black carbon
(rBC) containing particles, making the particle beam–laser beam
overlap critical in determining the collection efficiency (CE) for
rBC and associated non-refractory particulate matter (NR-PM). This
work evaluates the ability of the SP-AMS to quantify rBC and NR-PM
mass in internally mixed particles with different thicknesses of
organic coating. Using apparent relative ionization efficiencies for
uncoated and thickly coated rBC particles, we report measurements of
SP-AMS sensitivity to NR-PM and rBC, for Regal Black, the
recommended particulate calibration material. Beam width probe (BWP)
measurements are used to illustrate an increase in sensitivity for
highly coated particles due to narrowing of the particle beam, which
enhances the CE of the SP-AMS by increasing the laser beam–particle
beam overlap. Assuming complete overlap for thick coatings,
we estimate CE for bare Regal Black particles of 0.6 ± 0.1,
which suggests that previously measured SP-AMS sensitivities to
Regal Black were underestimated by up to a factor of 2. The
efficacy of the BWP measurements is highlighted by studies at a busy
road in downtown Toronto and at a non-roadside location, which show
particle beam widths similar to, but greater than that of bare Regal
Black and coated Regal Black, respectively. Further BWP measurements
at field locations will help to constrain the range of CE for fresh
and aged rBC-containing particles. The ability of the SP-AMS to
quantitatively assess the composition of internally mixed particles
is validated through measurements of laboratory-generated organic
coated particles, which demonstrate that the SP-AMS can quantify rBC
and NR-PM over a wide range of particle compositions and rBC core
sizes. |
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