A single-beam photothermal interferometer for in situ measurements of aerosol light absorption

Visser, Bradley; Röhrbein, Jannis; Steigmeier, Peter; Drinovec, Luka; Močnik, Griša; Weingartner, Ernest

We have developed a novel single-beam photothermal interferometer and present here its application for the measurement of aerosol light absorption. The use of only a single laser beam allows for a compact optical set-up and significantly easier alignment compared to standard dual-beam photothermal interferometers, making it ideal for field measurements. Due to a unique configuration of the reference interferometer arm, light absorption by aerosols can be determined directly – even in the presence of light-absorbing gases. The instrument can be calibrated directly with light-absorbing gases, such as inline-formulaNO2, and can be used to calibrate other light absorption instruments. The detection limits (1inline-formulaσ) for absorption for 10 and 60 s averaging times were determined to be 14.6 and 7.4 inline-formulaMm−1, respectively, which for a mass absorption cross section of 10 inline-formulam2 g−1 leads to equivalent black carbon concentration detection limits of 1460 and 740 inline-formulang m−3, respectively. The detection limit could be reduced further by improvements to the isolation of the instrument and the signal detection and processing schemes employed.



Visser, Bradley / Röhrbein, Jannis / Steigmeier, Peter / et al: A single-beam photothermal interferometer for in situ measurements of aerosol light absorption. 2020. Copernicus Publications.


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Rechteinhaber: Bradley Visser et al.

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