THE BONDING PROPERTIES OF HYDROGENATED AND FLUORINATED MOLECULES TO ZIRCONIUM-OXIDE THIN-FILMS - INFLUENCE OF SURFACE-DEFECTS AND WATER COADSORPTION

We have studied the influence of surface defects of ordered epitaxial films of ZrO2 grown on Pt(111) on the adsorption of H2O, diethyl ether (CH3CH2OCH2CH3), ethanol and their fluorinated analogs. Defects of the stoichiometric surface were produced by argon ion sputtering and characterized by a loss of oxygen as indicated by ion scattering spectroscopy (ISS). It is found that new adsorption sites are produced where H2O binds dissociatively producing H-2 upon heating above 400 K. Diethyl ether also has a new higher energy binding site on the defective surface. However the perfluorinated ether is not affected by the presence of the surface defects. The surface defects can be removed by annealing in O-2 or H2O. Coadsorption experiments with D2O indicated that there is a strong interaction with alcohols resulting in weakening of the D2O surface bond and in H-D exchange in the OH groups. Coadsorbed water is also seen to weaken the ether-surface bond in both the hydrogenated and fluorinated molecules.