We observe potential dependent alignment and hydrogen bonding of interfacial water molecules at a charged air/water and CCl4/water interface. The interfacial potential is a result of the presence of charged soluble surfactant adsorbed to the interface. We vary the interface potential by changing the surface charge density, the ionic strength, and the temperature while monitoring OH stretching m...

Vibrational sum frequency (VSF) spectra calculated using molecular dynamics (MD) simulations are compared with VSF experimental spectra to gain a clearer picture of water structure and bonding at the carbon tetrachloride-water (CCl4-H2O) and the 1,2-dichloroethane-water (DCE-H2O) liquid-liquid interfaces. The VSF spectral response from interfacial water at the CCl4-H2O interface contains spectr...

Colloids have long been known to facilitate the transport of contaminants in soils, but few direct observations have been made of transport and retention in unsaturated porous media. Studies have typically been limited to evaluation of column breakthrough curves, resulting in differing and sometimes conflicting proposed retention mechanisms. We carried out pore scale visualization studies of co...

The interfacial structure of water in contact with TiO2 is the key to understand the mechanism of photocatalytic water dissociation as well as photoinduced superhydrophilicity. We investigate the interfacial molecular structure of water at the surface of anatase TiO2, using phase-sensitive sum frequency generation spectroscopy together with spectra simulation using ab initio molecular dynamic t...

We investigate the energetic stability and dissociation dynamics of water adsorption at the LaAlO3 surface of the n-type LaAlO3/SrTiO3 (LAO/STO) interface and its effect on the electronic properties of the interface by carrying out first-principles electronic structure calculations. In an ambient atmosphere at room temperature the configuration of 1 monolayer (ML) of water molecules including 3...

Classical molecular dynamics simulations are used to present a detailed atomistic picture of the instantaneous local structures of water and the structural evolution of stationary and dynamically evolving graphene-water interfaces. The confinement effects are strongly coupled to the nature of the interface, which eventually governs its nanoscopic structural arrangements and interface dynamics. ...

Colloids have long been known to facilitate the transport of contaminants in soils, but few direct observations have been made of transport and retention in unsaturated porous media. Studies have typically been limited to evaluation of column breakthrough curves, resulting in differing and sometimes conflicting proposed retention mechanisms. We carried out pore scale visualization studies of co...

We use atomic force microscopy to in situ investigate the dynamic behavior of confined water at the interface between graphene and mica. The graphene is either uncharged, negatively charged, or positively charged. At high humidity, a third water layer will intercalate between graphene and mica. When graphene is negatively charged, the interface fills faster with a complete three layer water fil...

The surfaces of aqueous solutions are traditionally viewed as devoid of inorganic ions. Molecular simulations and surface-selective spectroscopic techniques show, however, that large polarizable anions and hydronium cations can be found (and even enhanced) at the surface and are involved in chemistry at the air/water interface. Here, we review recent studies of ions at the air/water interface a...

The dissociation and decomposition reactions of carbonic acid (H2CO3) in bulk water have been thoroughly studied, but little is known about its reactivity at the air-water interface. Herein, we investigate the dissociation reaction of H2CO3 at the air-water interface using ab initio molecular dynamics and metadynamics. Our results indicate that H2CO3 (pKa = 3.45) dissociates faster at the water...