PNNL

Abstract

We have investigated the structure and dynamics of thin water films adsorbed on TiO2(110) using infrared reflection absorption spectroscopy (IRAS) and ab-initio molecular dynamics. Infrared spectra were obtained for s- and p-polarized light with the plane of incidence parallel to the [001] and azimuths for water coverages = 4 monolayers. The spectra indicate strong anisotropy in the water films. The vibrational densities of states predicted by the ab-initio simulations for 1 and 2 monolayer coverages agree well with the observations. The results provide unprecedented insight into the structure of water on TiO2(110) and resolve a long-standing puzzle regarding the hydrogen-bonding within thin water films on this surface. The results also demonstrate the capabilities of polarization- and azimuthally-resolved IRAS for investigating the structure and dynamics of adsorbates on dielectric substrates.