Acoustic levitation with polarising optical microscopy (AL-POM): water uptake in a nanostructured atmospheric aerosol proxy

Adam Milsom, Adam M. Squires, Christopher Brasnett, William N. Sharratt, Annela M. Seddon, Christian Pfrang

Research output: Contribution to journalArticlepeer-review

1 Citation (SciVal)


Laboratory studies on levitated particles of atmospheric aerosol proxies have provided significant contributions to our understanding of aerosol processes. We present an experimental method combining acoustic levitation with polarising optical microscopy (AL-POM) to probe optically birefringent particles, such as the nanostructured surfactant atmospheric aerosol proxy studied here. Birefringent particles were subjected to a step increase in humidity. A decrease in birefringence was measured over time as a result of a nanostructure change, confirmed by complementary synchrotron X-ray scattering. A multi-layer water uptake model was created and fitted to the experimental data, revealing a water diffusion coefficient increase by ca. 5-6 orders of magnitude upon phase transition. This has implications for the timescale of water uptake in surfactant-containing aerosols and their atmospheric lifetimes. This experimental setup has strong potential to be used in conjunction with other levitation methods and in different contexts concerning birefringent materials such as crystallisation.

Original languageEnglish
Pages (from-to)1642-1650
Number of pages9
JournalEnvironmental Science: Atmospheres
Issue number11
Early online date26 Sept 2023
Publication statusPublished - 26 Sept 2023

Bibliographical note

Funding Information:
AM acknowledges funding by the NERC SCENARIO DTP (NE/L002566/1) and support from the NERC CENTA DTP. This work was carried out with the support of the Diamond Light Source (UK), instrument I22 (proposals SM23852 and SM17791). Nick Terrill, Andy Smith, Tim Snow and Olga Shebanova (DLS) are acknowledged for their support during experiments at the DLS. The computations described in this paper were performed using the University of Birmingham's BlueBEAR HPC service, which provides a High Performance Computing service to the University's research community. This research has also been supported by the Natural Environment Research Council (grant no. NE/T00732X/1, NE/G000883/1 and NE/G019231/1) and the Royal Society (grant no. 2007/R2).

ASJC Scopus subject areas

  • Analytical Chemistry
  • Chemistry (miscellaneous)
  • Environmental Chemistry
  • Pollution


Dive into the research topics of 'Acoustic levitation with polarising optical microscopy (AL-POM): water uptake in a nanostructured atmospheric aerosol proxy'. Together they form a unique fingerprint.

Cite this