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| Titel |
Single particle characterization using a light scattering module coupled to a time-of-flight aerosol mass spectrometer |
| VerfasserIn |
E. S. Cross, T. B. Onasch, M. Canagaratna, J. T. Jayne, J. Kimmel, X.-Y. Yu, M. L. Alexander, D. R. Worsnop, P. Davidovits |
| 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 ; 9, no. 20 ; Nr. 9, no. 20 (2009-10-19), S.7769-7793 |
| Datensatznummer |
250007691
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| Publikation (Nr.) |
 copernicus.org/acp-9-7769-2009.pdf |
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| Zusammenfassung |
We present the first single particle results obtained with an Aerodyne
time-of-flight aerosol mass spectrometer coupled with a light scattering
module (LS-ToF-AMS). The instrument was deployed at the T1 ground site
approximately 40 km northeast of the Mexico City Metropolitan Area as part
of the MILAGRO field study in March of 2006. The LS-ToF-AMS acquires both
ensemble average and single particle data. Over a 75-h sampling period
from 27–30 March 2006, 12 853 single particle mass spectra were
optically-triggered and saved. The single particles were classified based on
observed vaporization histories and measured chemical compositions. The
single particle data is shown to provide insights on internal AMS collection
efficiencies and ambient mixing state information that augments the ensemble
data.
Detection of correlated light scattering and chemical ion signals allowed
for a detailed examination of the vaporization/ionization process for single
particles measured with the AMS instrument. Three particle vaporization
event types were identified as a fraction of the total number of particles
detected: (1) 23% with prompt vaporization, (2) 26% with delayed
vaporization, and (3) 51% characterized as null. Internal consistency
checks show that average single particle nonrefractory mass and chemical
composition measurements were in reasonable agreement with ensemble
measurements and suggest that delayed and null vaporization events are the
dominant source of the nonunit collection efficiency of the AMS. Taken
together, the simultaneous prompt single particle and aerosol ensemble
measurements offer insight into the mixing state and atmospheric
transformations of ambient aerosol particles. |
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