The hydrated proton at the water liquid/vapor interface

The hydrated proton was studied at the water liquid/vapor interface using the multistate empirical valence bond (MS-EVB) methodology, which enables the migration of the excess proton to and about the interface through the fluctuating bond topology described by the Grotthuss shuttle mechanism. It was found in our model that the hydrated excess proton displays a marked preference for water liquid/vapor interfaces. The resulting stable surface structures can be explained through an examination of the bond network formed between the water/proton moiety and solvating water. These results suggest the excess proton can effectively behave as an amphiphile, displaying both hydrophobic and hydrophilic character.