The microscopic picture of ions at the aqueous liquid-vapor interface continues to be an active area of research, despite a long history of both experimental and theoretical investigations. While it has become clear that certain ions, such as Br– and I–, have a propensity to reside at the aqueous liquid-vapor interface, some questions remain on the relative importance of various ion-specific properties that influence their spatial distribution. In a previous study,1 we systematically explored the effect of ion size and determined that differences in size alone are sufficient to cause spatial inhomogeneities with larger anions being enriched near the Gibbs dividing surface. Here, we extend that study to include temperature effects. We perform configurational-bias Monte Carlo simulations in the Gibbs ensemble to investigate the spatial distribution of mixtures of differently sized ions from 258 K to 308 K. The non-polarizable TIP4P model is used for water, and special models that vary only in size (i.e., their Lennard-Jones σ parameter) are used for the ions. System properties studied include surface tension, interfacial width, spatial distributions, pair correlation functions, and an analysis of hydrogen bonding at the interface. 1Eggimann, B. L., & Siepmann, J. I. J. Phys. Chem. C, 2008, 112, 210. doi:10.1021/jp076054d

Temperature effects on the spatial distribution of electrolyte mixtures at the aqueous liquid-vapor interface

249th National Meeting (2015)

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