O adsorption and incipient oxidation of the Mg(0001) surface

Abstract

First principles density functional calculations are used to study the early oxidation stages of the Mg(0001) surface for oxygen coverages 1/16 <= Theta <= 3 monolayers. It is found that at very low coverages O is incorporated below the topmost Mg layer in tetrahedral sites. At higher oxygen-load the binding in on-surface sites is increased but at one monolayer coverage the on-surface binding is still about 60 meV weaker than for subsurface sites. The subsurface octahedral sites are found to be unfavorable compared to subsurface tetrahedral sites and to on-surface sites. At higher coverages oxygen adsorbs both under the surface and up. Our calculations predict island formation and clustering of incorporated and adsorbed oxygen in agreement with previous calculations. The calculated configurations are compared with the angle-scanned x-ray photoelectron diffraction experiment to determine the geometrical structure of the oxidized Mg(0001) surface.Comment: 10 pages, 5 figure

Negatively Charged Ions on Mg(0001) Surfaces: Appearance and Origin of Attractive Adsorbate-Adsorbate Interactions

“…Oxygen favors the tetrahedral subsurface site (below the hcp on-surface site) for coverages up to 0.75 ML and moves to a threefold hollow hcp site in a position coplanar with the top Mg layer at θ ¼ 1 ML. In each of these cases, we obtain a positive E b value, indicating that the dissociative adsorption of X 2 is exothermic at T ¼ 0 K, in agreement with previous work [15,16]. Interestingly, a decrease in the binding energy with increasing coverage, i.e., the expected behavior for electronegative adatoms on a metal surface, is seen only for Cl.…”

Mg-based photocathodes prepared by ns, ps and fs PLD for the production of high brightness electron beams

“…The bending can be explained taking into account the chemisorption process of residual gas, such as hydrogen or oxygen on the film surface [11][12][13]. The hydrogen chemisorption on Mg film surface has been reported to induce a lowering of the work function of the metal [9].…”

The effect of defects on the hydrogenation in Mg (0001) surface

“…Considering the oxide model, we notice that Schrö der et al [29] investigated the early oxidation stages of the Mg(0 0 0 1) surface with different oxygen coverages. It was found that at low coverages (u < 0.5 ML) the first O atom chemisorbed in the oxidation process binds in a subsurface tetrahedral site.…”