Core-Level Binding Energy Reveals Hydrogen Bonding Configurations of Water Adsorbed on TiO_{2}(110) Surface

Using x-ray photoelectron spectroscopy of the oxygen 1s core level, the ratio between intact (D_{2}O) and dissociated (OD) water in the hydrated stoichiometric TiO_{2}(110) surface is determined at varying coverage and temperature. In the submonolayer regime, both the D_{2}O∶OD ratio and the core-level binding energy of D_{2}O (ΔBE) decrease with temperature. The observed variations in ΔBE are shown with density functional theory to be governed crucially and solely by the local hydrogen bonding environment, revealing a generally applicable classification and details about adsorption motifs.