Themed collection Particle Levitation to Address Challenges in Atmospheric Science

We present acoustic levitation combined with polarising optical microscopy (AL-POM). Fatty acid aerosols were probed and a model fit revealed a ca. 5–6 orders of magnitude difference in water diffusion coefficient upon a phase transition between optically birefringent and non-birefringent phases.

Organic aerosol is a highly complex mixture of ∼10⁴ to 10⁵ unique compounds all possessing their own set of physico-chemical properties such as saturation vapour pressure and hygroscopicity.

The hygroscopic growth of single levitated atmospheric sea salt particles is re-examined by combining optical trapping with accurate mass measurements.

The acidity of atmospheric aerosols controls their impacts on heterogeneous and multiphase reactions, cloud formation, and human health.

We directly measure the Fe(III)-catalyzed SO₂ conversion in single microdroplet trapped and levitated with a gradient-force aerosol optical tweezer. There was a significant acceleration in the formation of SO₂ to sulfate conversion on the surface of the aerosol microdroplets.

Electrodynamic balance–mass spectrometry allows to study the ozonolysis of linoleic acid under strongly different ozone concentrations and reveals the importance of autoxidation at low ozone concentrations.

Internally-mixed aerosol particles containing organic molecules and inorganic salts exhibit hygroscopic growth, viscosity and diffusion properties that have a non-linear dependence on composition.

Secondary organic aerosol (SOA) particles in Earth's atmosphere can exist in phase states where mass transport and chemical transformations are greatly impeded.

We applied a time-resolved, optical trapping-Raman spectroscopy (OT-RS) technique to characterize single, trapped bioaerosol particles under well-controlled reactive conditions that mimic the native state of particles in the atmosphere.