The influence of sodium on the adsorption of water on SrTiO3(100)-1 x 1 surfaces

High resolution electron energy loss spectroscopy has been used to study the adsorption of water on the clean and Na modified SrTiO3(1 0 0)-1 x 1 surfaces. The vibrational spectrum of clean SrTiO3 shows three dipole active bands, characteristic of perovskite materials, at 170, 460 and 730 cm(-1). In good agreement with previously published experimental results, we show that water does not adsorb on the clean defect free SrTiO3(1 0 0)-1 x 1 surface. On the other hand, the vibrational spectra of the Na modified SrTiO3(1 0 0)-1 x 1 surface exposed to water shows clearly an OH stretching vibration which indicates the presence of hydroxyl species at the surface. The continuous observation of the 1 x 1 pattern in low energy electron diffraction indicates that the surface reconstruction is preserved even after exposure of the surface to water. (C) 2001 Elsevier Science B.V. All rights reserved.