Molecular dynamics computer simulations of solvation dynamics at liquid/liquid interfaces

The solvent dynamic response to electronic transitions at several liquid/li quid interfaces is studied using molecular dynamics computer simulations. T he interfaces examined are between water and one of four different organic liquids. The electronic transitions involve a change in the permanent dipol e of a dipolar solute located at the interface. Two locations of the solute relative to the interface are studied and are compared with the same proce ss in each of the bulk liquids. The different organic liquids are 1-octanol , 1,2-dichloroethane, n-nonane, and carbon tetrachloride. They are selected to give a range of polarity and of interface structure. The solvent dynami c response at the interface is much more complex than in the bulk. The tota l relaxation involves multiple time scales corresponding to contributions f rom both solvents and from the unique structural and dynamic properties of the interface. In particular, interfacial water relaxation may contain a sl ow component not present in the bulk nor at the water liquid/vapor interfac e. (C) 2001 American Institute of Physics.