Model surface studies of metal oxides: Adsorption of water and methanol on ultrathin MgO films on Mo(100)

Abstract

Adsorption and reaction of formic acid on NiO(100) films on Mo(100): Temperature programmed desorption and high resolution electron energy loss spectroscopy studies J. Chem. Phys. 97, 9447 (1992); 10.1063/1.463268 CO interaction with ultrathin MgO films on a Mo(100) surface studied by infrared reflection-absorption spectroscopy, temperature programmed desorption, and xray photoelectron spectroscopy Model surface studies of magnesium oxide have been carried out using surface sensitive techniques. Ultrathin MgO films have been synthesized under ultrahigh vacuum (UHY) conditions by thermally evaporating Mg onto MoC 1(0) in the presence of oxygen. Low-energy electron diffraction (LEED) studies indicate that the MgO films grow epitaxially with the (100) face ofMgO oriented parallel to Mo( 1(0). The MgO films, prepared under optimum synthesis conditions, have essentially one-to-one stoichiometry, are nearly free from pointlike surface defects, and have properties essentially identical to those of bulk, single-crystal MgO. Adsorption of water and methanol onto the MgO films has been studied using high-resolution electron energy-loss spectroscopy (HREELS) and temperature programmed desorption (TPD). In order to circumvent the difficulty associated with intense multiple surface optical phonon (Fuchs-Kliewer modes) losses, a new approach to acquisition ofHREELS data has been demonstrated. This new approach enables the direct observation of weak loss features due to excitation of the adsorbates without serious interference from multiple phonon losses. Our HREELS studies show that water and methanol undergo heterolytic dissociation, leading to the formation of hydroxyl and methoxy species, respectively. 3892

Mechanisms of and Effect of Coadsorption on Water Dissociation on an Oxygen Vacancy of the MgO(100) Surface

“…[61] The difference between the calculated and experimental frequency data indicates that the coadsorption water under experimental measurement conditions may reduce the bond strength of OH species.…”

From Interfacial Water to Macroscopic Observables: A Review

“…One such important metal oxide is magnesium oxide (MgO). Both experimental tools (Coluccia et al 1987;Knozinger et al 1993;Peng and Barteau 1991;Wu et al 1992;Zhou and Cowin 1996) and theoretical tools (Deleeuw et al 1995;Langel and Parrinello 1994;Refson et al 1995;Scamehorn et al 1993) have been used to investigate the water/MgO interface. McCarthy et al (1996) parameterized a two-body force field to describe solid-water interactions based on prior ab initio correlation-corrected periodic Hartree-Fock theoretical results (Scamehorn et al 1993(Scamehorn et al , 1994.…”

Enhanced Reactivity at Metal−Oxide Interface: Water Interaction with MgO Ultrathin Films

“…5 MgO films are among the most studied systems since, due to their relatively simple electronic and atomic structure, they were assumed as a model for investigating metal-oxide interface properties. 6 Ag(100) is an optimal substrate for the film deposition, since the small mismatch between the Ag and the MgO lattice constants allows for epitaxial growth, as demonstrated recently by scanning tunneling microscopy (STM). 7,8 Such experiments, aimed at clarifying the structure of MgO layers in the very early stages of film growth, showed that initially both MgO islands and pyramidal structures form on the Ag(100) surface.…”