Cantilever-enhanced photoacoustic measurement of light-absorbing aerosols

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Karhu , J , Kuula , J , Virkkula , A , Timonen , H , Vainio , M & Hieta , T 2021 , ' Cantilever-enhanced photoacoustic measurement of light-absorbing aerosols ' , Aerosol Science and Technology , vol. 56 , no. 1 , pp. 92-100 .

Title: Cantilever-enhanced photoacoustic measurement of light-absorbing aerosols
Author: Karhu, Juho; Kuula, Joel; Virkkula, Aki; Timonen, Hilkka; Vainio, Markku; Hieta, Tuomas
Contributor organization: Department of Chemistry
Date: 2021-11-25
Language: eng
Number of pages: 9
Belongs to series: Aerosol Science and Technology
ISSN: 0278-6826
Abstract: Photoacoustic detection is a sensitive method for measurement of light-absorbing particles directly in the aerosol phase. In this article, we demonstrate a new sensitive technique for photoacoustic aerosol absorption measurements using a cantilever microphone for the detection of the photoacoustic signal. Compared to conventional diaphragm microphones, a cantilever offers increased sensitivity by up to two orders of magnitude. The measurement setup uses a photoacoustic cell from Gasera PA201 gas measurement system, which we have adapted for aerosol measurements. Here we reached a noise level of 0.013 Mm(-1) (one standard deviation) with a sampling time of 20 s, using a simple single-pass design without a need for a resonant acoustic cell. The sampling time includes 10 s signal averaging time and 10 s sample exchange, since the photoacoustic cell is designed for closed cell operation. We demonstrate the method in measurements of size-selected nigrosin particles and ambient black carbon. Due to the exceptional sensitivity, the technique shows great potential for applications where low detection limits are required, for example size-selected absorption measurements and black carbon detection in ultra clean environments.
Subject: Hans Moosmuller
116 Chemical sciences
Peer reviewed: Yes
Rights: cc_by
Usage restriction: openAccess
Self-archived version: publishedVersion

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