The evolution of surface structure during simulated atmospheric ageing of nano-scale coatings of an organic surfactant aerosol proxy

Abstract

Atmospheric aerosol particles can be coated with organic material, impacting on aerosol atmospheric lifetime and urban air quality. Coatings of organic material are also found on indoor surfaces such as...

Exploring the Nanostructures Accessible to an Organic Surfactant Atmospheric Aerosol Proxy

“…Oleic acid is a commonly emitted organic surfactant, with sources including marine , and urban emissions. − This has made it the compound of choice as a reactive organic surfactant aerosol proxy, e.g., see refs − . Its surface-active nature can cause it to form self-assembled nanostructures when mixed with water and its salt (sodium oleate), these are called lyotropic liquid crystal (LLC) phases. ,, These nanostructures can range from spherical micelles to lamellar multilayers and cylindrical arrangements with water channels, among others .…”

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

“…This kind of surface orientation has been observed previously in levitated droplets of LLC phases 3 and in nanometre-scale films of this system. 45…”

“…This kind of surface orientation has been observed previously in levitated droplets of LLC phases 3 and in nanometre-scale lms of this system. 45 Diffusion is highly anisotropic in the lamellar phase. 46,47 If lamellar bilayers are highly aligned parallel to the droplet surface (as observed here), water uptake is likely to be affected.…”

Acoustic levitation combined with laboratory-based small-angle X-ray scattering (SAXS) to probe changes in crystallinity and molecular organisation

“…The exploration of nanoscale structures and their properties using small-angle X-ray scattering (SAXS) is a signicant area of interest across various scientic disciplines including materials science, 1 biology, 2 electrochemistry 3 and atmospheric chemistry. [4][5][6][7][8][9][10] Acoustic levitation is a non-contact manipulation technique and has emerged as a powerful tool for studying particles on the micrometre-to-millimetre scale, facilitating investigations into their physical and chemical properties. 11,12 Combined with laboratory based SAXS, acoustic levitation offers a way to probe the structural properties of levitated samples.…”

“…However, studying aerosols is challenging due to their dynamic nature and diverse compositions. By employing single particle levitation techniques such as optical tweezers, 22,23 electrodynamic balance 24,25 and acoustic levitation, 4,[7][8][9]26 researchers can isolate individual aerosol particles in a controlled environment, avoiding surface interactions and gravitational settling. Coupling acoustic levitation with SAXS enables in-depth characterisation of aerosol structures, providing insights into their internal organisation and interactions with surrounding species.…”