A dual-wavelength photothermal aerosol absorption monitor. Design, calibration and performance
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Autor:innen
Drinovec, Luka
Jagodič, Uroš
Pirker, Luka
Škarabot, Miha
Kurtjak, Mario
Vidović, Kristijan
Ferrero, Luca
Visser, Bradley
Röhrbein, Jannis
Autor:in (Körperschaft)
Publikationsdatum
2022
Typ der Arbeit
Studiengang
Typ
01A - Beitrag in wissenschaftlicher Zeitschrift
Herausgeber:innen
Herausgeber:in (Körperschaft)
Betreuer:in
Übergeordnetes Werk
Atmospheric Measurement Techniques
Themenheft
DOI der Originalpublikation
Link
Reihe / Serie
Reihennummer
Jahrgang / Band
15
Ausgabe / Nummer
12
Seiten / Dauer
3805-3825
Patentnummer
Verlag / Herausgebende Institution
Copernicus
Verlagsort / Veranstaltungsort
Göttingen
Auflage
Version
Programmiersprache
Abtretungsempfänger:in
Praxispartner:in/Auftraggeber:in
Zusammenfassung
There exists a lack of aerosol absorption measurement techniques with low uncertainties and without artefacts. We have developed the two-wavelength Photothermal Aerosol Absorption Monitor (PTAAM-2λ), which measures the aerosol absorption coefficient at 532 and 1064 nm. Here we describe its design, calibration and mode of operation and evaluate its applicability, limits and uncertainties. The 532 nm channel was calibrated with ∼ 1 µmol mol−1 NO2, whereas the 1064 nm channel was calibrated using measured size distribution spectra of nigrosin particles and a Mie calculation. Since the aerosolized nigrosin used for calibration was dry, we determined the imaginary part of the refractive index of nigrosin from the absorbance measurements on solid thin film samples. The obtained refractive index differed considerably from the one determined using aqueous nigrosin solution. PTAAM-2λ has no scattering artefact and features very low uncertainties: 4 % and 6 % for the absorption coefficient at 532 and 1064 nm, respectively, and 9 % for the absorption Ångström exponent. The artefact-free nature of the measurement method allowed us to investigate the artefacts of filter photometers. Both the Aethalometer AE33 and CLAP suffer from cross sensitivity to scattering – this scattering artefact is most pronounced for particles smaller than 70 nm. We observed a strong dependence of the filter multiple scattering parameter on the particle size in the 100–500 nm range. The results from the winter ambient campaign in Ljubljana showed similar multiple scattering parameter values for ambient aerosols and laboratory experiments. The spectral dependence of this parameter resulted in AE33 reporting the absorption Ångström exponent for different soot samples with values biased 0.23–0.35 higher than the PTAAM-2λ measurement. Photothermal interferometry is a promising method for reference aerosol absorption measurements.
Schlagwörter
Fachgebiet (DDC)
620 - Ingenieurwissenschaften und Maschinenbau
Veranstaltung
Startdatum der Ausstellung
Enddatum der Ausstellung
Startdatum der Konferenz
Enddatum der Konferenz
Datum der letzten Prüfung
ISBN
ISSN
1867-8548
Sprache
Englisch
Während FHNW Zugehörigkeit erstellt
Ja
Publikationsstatus
Veröffentlicht
Begutachtung
Peer-Review der ganzen Publikation
Open Access-Status
Gold
Lizenz
Zitation
DRINOVEC, Luka, Uroš JAGODIČ, Luka PIRKER, Miha ŠKARABOT, Mario KURTJAK, Kristijan VIDOVIĆ, Luca FERRERO, Bradley VISSER, Jannis RÖHRBEIN, Ernest WEINGARTNER, Daniel M. KALBERMATTER, Konstantina VASILATOU, Tobias BÜHLMANN, Celine PASCALE, Thomas MÜLLER, Alfred WIEDENSOHLER und Griša MOČNIK, 2022. A dual-wavelength photothermal aerosol absorption monitor. Design, calibration and performance. Atmospheric Measurement Techniques. 2022. Bd. 15, Nr. 12, S. 3805–3825. DOI 10.5194/amt-15-3805-2022. Verfügbar unter: https://doi.org/10.26041/fhnw-7560