Cantilever-enhanced photoacoustic measurement of light-absorbing aerosols

Juho Karhu, Joel Kuula, Aki Virkkula, Hilkka Timonen, Markku Vainio, Tuomas Hieta

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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.

Original languageEnglish
Pages (from-to)92-100
Number of pages9
JournalAerosol Science and Technology
Volume56
Issue number1
Early online date17 Nov 2021
DOIs
Publication statusPublished - 2022
Publication typeA1 Journal article-refereed

Keywords

  • Hans Moosmüller

Publication forum classification

  • Publication forum level 1

ASJC Scopus subject areas

  • Environmental Chemistry
  • Materials Science(all)
  • Pollution

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