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O: Fachverband Oberflächenphysik

O 58: Mini-Symposium: Molecular scale investigations of liquid-vapor interfaces II

O 58.5: Talk

Wednesday, March 3, 2021, 12:10–12:30, R1

Mass transfer of water at organic aerosol interfaces — •Matus E. Diveky, Michael Gleichweit, Sandra Roy, and Ruth Signorell — Laboratory of Physical Chemistry, ETH Zürich, Vladimir-Prelog-Weg 2, CH-8093 Zürich, Switzerland

Interfacial mass transport plays a crucial role in defining growth rates of aerosols. To properly assess the potential of aerosols to behave as condensation nuclei, it is of paramount importance to unravel the kinetics of mass transport through the interface. The important parameter defining the probability of a gas-phase molecule accommodating to the surface upon collision is called mass accommodation coefficient. Despite the widespread relevance of accommodation coefficients, values for many important systems are still lacking.

We employ Photothermal Single-Particle Spectroscopy (PSPS) to investigate the water accommodation on miscible organic aerosol particles. Such systems remain largely uncharted despite the abundance of organic matter and gas-phase water molecules in the atmosphere. The PSPS technique combines photoacoustic spectroscopy with modulated Mie scattering performed simultaneously on a single-particle level.

Through a careful droplet manipulation inside an optical trap, we study the temperature and relative humidity dependence of the mass accommodation coefficient of water on organic miscible droplets. Our results hint at a negative correlation between accommodation coefficient and temperature. Lastly, we argue that the PSPS technique can be used to restrict the lower limit of the mass accommodation of water on liquid water.