Molecular Simulation of Ion Transport at the Water/Vapor Interface

Molecular dynamics was used to quantify the role of the size, charge and polarisability of F–, Cl–, Br–, I– and Na+ ions in their distribution in the water/vapour interface system. Our results show that the larger polarizable anions I– and Br– is attracted to the surface which is traced back to surface-modified ion hydration, while the F– was repelled from the interface and the Cl– occupied the total volume of the water slab. Moreover, by artificially increasing the ions charge, anions were localized to the center of the water slab. These results demonstrate that the effect of polarizability cannot be neglected in the transport mechanism.