Laser ablation aerosol particle time-of-flight mass spectrometer (LAAPTOF): performance, reference spectra and classification of atmospheric samples
The laser ablation aerosol particle time-of-flight mass spectrometer (LAAPTOF, AeroMegt GmbH) is able to identify the chemical composition and mixing state of individual aerosol particles, and thus is a tool for elucidating their impacts on human health, visibility, ecosystem, and climate. The o...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-04-01
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| Series: | Atmospheric Measurement Techniques |
| Online Access: | https://www.atmos-meas-tech.net/11/2325/2018/amt-11-2325-2018.pdf |
| Summary: | The laser ablation aerosol particle time-of-flight mass
spectrometer (LAAPTOF, AeroMegt GmbH) is able to identify the chemical
composition and mixing state of individual aerosol particles, and thus is a
tool for elucidating their impacts on human health, visibility, ecosystem, and
climate. The overall detection efficiency (ODE) of the instrument we use was
determined to range from ∼ (0.01 ± 0.01) to
∼ (4.23 ± 2.36) % for polystyrene latex (PSL) in the
size range of 200 to 2000 nm, ∼ (0.44 ± 0.19) to
∼ (6.57 ± 2.38) % for ammonium nitrate
(NH<sub>4</sub>NO<sub>3</sub>), and ∼ (0.14 ± 0.02) to
∼ (1.46 ± 0.08) % for sodium chloride (NaCl) particles
in the size range of 300 to 1000 nm. Reference mass spectra of 32 different
particle types relevant for atmospheric aerosol (e.g. pure compounds
NH<sub>4</sub>NO<sub>3</sub>, K<sub>2</sub>SO<sub>4</sub>, NaCl, oxalic acid, pinic acid, and pinonic
acid; internal mixtures of e.g. salts, secondary organic aerosol, and
metallic core–organic shell particles; more complex particles such as soot
and dust particles) were determined. Our results show that internally mixed
aerosol particles can result in spectra with new clusters of ions, rather
than simply a combination of the spectra from the single components. An
exemplary 1-day ambient data set was analysed by both classical fuzzy
clustering and a reference-spectra-based classification method. Resulting
identified particle types were generally well correlated. We show how a
combination of both methods can greatly improve the interpretation of single-particle data in field measurements. |
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| ISSN: | 1867-1381 1867-8548 |