AVS 58th Annual International Symposium and Exhibition
    Surface Science Division Monday Sessions
       Session SS1-MoM

Paper SS1-MoM6
Infrared Spectroscopy of Thin Water Films on TiO2(110): Anisotropy and the Hydrogen-Bonding Network

Monday, October 31, 2011, 10:00 am, Room 109

Session: Water Films & Environmental Interfaces
Presenter: Greg Kimmel, Pacific Northwest National Laboratory
Authors: G.A. Kimmel, Pacific Northwest National Laboratory
M. Baer, Pacific Northwest National Laboratory
N.G. Petrik, Pacific Northwest National Laboratory
C.J. Mundy, Pacific Northwest National Laboratory
R.J. Rousseau, Pacific Northwest National Laboratory
Correspondent: Click to Email
The structure of water at interfaces is crucial for processes ranging from photocatalysis to protein folding. We have investigated the structure of thin water films adsorbed on TiO2(110) using reflection-absorption infrared spectroscopy (RAIRS), temperature programmed desorption and ab-initio molecular dynamics simulations. Infrared spectra were obtained for light with the plane of incidence parallel and perpendicular to the [001] azimuth of TiO2(110) for water coverages ≤ 4 monolayers (ML). The spectra indicate strong anisotropy in the water structure along the two major azimuths. For both 1 and 2 ML coverages, the water films form “strings” of water molecules parallel to the bridging oxygen rows on the (110) surface. Within the strings, each molecule participates in 4 bonds, such that the films have no dangling hydrogen bonds. The vibrational densities of states predicted by the ab-initio simulations for 1 and 2 monolayer coverages agree well with the observations. Despite extensive prior research, the structure of water films on TiO2(110) has remained controversial. Our results provide crucial, molecular-level information about the structure of water films on this benchmark transition metal oxide.