Structure and geometry of water adsorbed on the MgO(100) surface

Adsorption of D2O on the MgO(100)/Mo(100) surface has been studied using temperature programmed desorption (TPD), reflection absorption infrared spectroscopy (RAIRS) and low energy electron diffraction (LEED). The epitaxially grown MgO(100) films show virtually identical water TPD spectra as the single crystal MgO(100) surface. The first, chemisorbed layer is adsorbed with the plane of the molecule nominally parallel to the surface. A (3 × 2) LEED pattern with missing spots at (0, 12) was also observed. Based on the LEED and RAIRS results, a real space structure for the D2O adsorption on the MgO(100) surface is proposed. This structure implies an absolute coverage of 0.67 ML (D2O molecules per Mg cation) for the first, chemisorbed layer.