Ions at the air-water interface: An end to one hundred year old mystery?

TL;DR

This paper introduces a new theoretical framework for understanding the electrolyte-air interface, accurately predicting ionic profiles and surface properties, and resolving longstanding questions about surface chemistry and the Hofmeister effect.

Contribution

A novel theory that explicitly calculates ionic density profiles, surface tension, and electrostatic potential differences at the electrolyte-air interface, aligning well with experimental data.

Findings

Excellent agreement between theory and experiments

New insights into the Hofmeister effect

Improved understanding of aerosol surface chemistry

Abstract

Availability of highly reactive halogen ions at the surface of aerosols has tremendous implications for the atmospheric chemistry. Yet neither simulations, experiments, nor existing theories are able to provide a fully consistent description of the electrolyte-air interface. In this paper a new theory is proposed which allows us to explicitly calculate the ionic density profiles, the surface tension, and the electrostatic potential difference across the solution-air interface. Predictions of the theory are compared to experiments and are found to be in excellent agreement. The theory also sheds new light on one of the oldest puzzles of physical chemistry -- the Hofmeister effect.