Electric Charge Effect on the Water Mass Transfer across Mixed Aqueous-Organic Droplet Interfaces

Understanding gas-particle mass transport is essential for predicting aerosol behavior in the atmosphere and in industrial processes. The mass accommodation coefficient, α_M, is a key parameter describing this exchange. Defined as the probability of a gas-phase molecule adhering to a particle upon collision, α_M presents a highly surface-sensitive property. Aqueous atmospheric aerosol droplets carry electric charges, which accumulate near the surface; however, their influence on the gas-particle mass transport remains elusive. To access the influence of charge on α_M, we combined an aerosol charging method with photothermal single-particle spectroscopy, enabling direct water mass exchange measurements on the surface of single aerosol droplets. We investigated charged and neutral aqueous glycerol and tetraethylene glycol droplets across a wide range of concentrations and temperatures. The micrometre-sized droplets carried approximately 10³ elementary charges─exceeding typical atmospheric aerosol charge levels─yet our results show that α_M is independent of the droplet charge and instead is dominated by composition and temperature. Theoretical estimates of the charge-dipole and dipole-dipole interaction energies corroborate this finding, highlighting that under atmospherically relevant conditions, electric charge plays a negligible role in the mass accommodation process.