Oxygen adsorption on Ag(111): A density-functional theory investigation (original) (raw)
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Adsorption of atomic oxygen on Ag(): a study based on density-functional theory
Surface Science, 2002
We present a theoretical study--based on first principles calculations--aimed at characterizing the surface reconstructions which occur at the Ag(0 0 1) surface when oxygen is dosed on it. We first model this system at different coverages using (1  1), c(2  2), and p(2  2) structures of oxygen atoms adsorbed on the hollow sites of the Ag(0 0 1) surface. The corresponding equilibrium geometries are obtained by accurate energy minimizations performed within density-functional theory in the local density or in the generalized gradient approximations. We then compare the energies of these structures with that of oxygen adsorbed on a (2 ffiffi ffi 2 p  ffiffi ffi 2 p ) missing-row reconstructed substrate, recently proposed to be the stable phase at low temperature on the basis of X-ray photo-electron diffraction experiments. We do find evidence that the surface structure might be stabilized by a missing-row reconstruction, though our predicted geometry differs from that previously proposed. Ó
Structure and dynamics of oxygen adsorbed on Ag(100) vicinal surfaces
Physical Review B, 2004
The structure and dynamics of atomic oxygen adsorbed on Ag(410) and Ag(210) surfaces has been investigated using density functional theory. Our results show that the adsorption configuration in which O adatoms decorate the upper side of the (110) steps forming O-Ag-O rows is particularly stable for both surfaces. On Ag , this arrangement is more stable than other configurations at all the investigated coverages. On Ag(410), adsorption on the terrace and at the step edge are almost degenerate, the former being slightly preferred at low coverage while the latter is stabilized by increasing the coverage. These findings are substantiated by a comparison between the vibrational modes, calculated within density-functional perturbation theory, and the HREEL spectrum which has been recently measured in these systems.
On-surface and subsurface adsorption of oxygen on stepped Ag(210) and Ag(410) surfaces
Surface Science, 2004
The adsorption of atomic oxygen and its inclusion into subsurface sites on Ag and Ag(410) surfaces have been investigated using density functional theory. We find that-in the absence of adatoms on the first metal layer-subsurface adsorption results in strong lattice distortion which makes it energetically unfavoured. However subsurface sites are significantly stabilised when a sufficient amount of O adatoms is present on the surface. At high enough O coverage on the Ag(210) surface the mixed on-surface + subsurface O adsorption is energetically favoured with respect to the on-surface only adsorption. Instead, on the Ag(410) surface, at the coverage we have considered (3/8 ML), the existence of stable terrace sites makes the subsurface O incorporation less favourable. These findings are compatible with the results of recent HREEL experiments which have actually motivated this work.
Sequential population of adsorption sites driven by surface stress
Physical Review B, 2010
We performed a combined experimental and theoretical study of surface stress and structure of the adsorption of oxygen on Ir͑001͒. We find that up to an oxygen coverage of half a monolayer oxygen adsorbs in bridge sites, whereas at larger coverage between 0.5 and 0.75 adsorption occurs in both bridge and hollow sites. A compressive surface stress change of −2.2 N / m is measured, and substantial lattice relaxations are identified by surface x-ray diffraction. Density-functional theory calculations reveal that anisotropic O-induced surface stress is a key factor for the sequential occupation of the adsorption sites.
Theory of scanning tunneling microscopy of oxygen adsorption on Ag(110) surface
Solid State Communications
Oxygen adsorption on Ag(110) surface has been investigated by means of firstprinciples total-energy and force calculations for repeated-slab geometries within the local density approximation (LDA). The added row model composed of oxygen atom and silver atom has been believed to be one of the most realistic models. We have already obtained the optimized geometry of the added row model. Using the optimized positions, the simulation of STM images and STS spectra has been performed based on the Bardeen's perturbation theory. Compared with the experimental data, the theoretical results seem to show a fairly good correspondence. Recently, Besenbacher et.al, have published their STM
Theory of Adsorption on Metal Substrates
Handbook of Surface Science, 2000
Volume 2, edited by K. Horn and M. Scheffler 5.8 Co-adsorption [the example CO plus O on Ru(0001)] 286 5.9 Chemical reactions at metal surfaces 5.9.1 The problems with "the" transition state 5.9.2 Dissociative adsorption and associative desorption of H 2 at transition metals 5.9.2.1 The potential-energy surface of H 2 at transition-metal surfaces 5.9.2.2 The dynamics of H 2 dissociation at transition-metal surfaces 5.10 The catalytic oxidation of CO 5.11 Summary outline of main points References 287
Surface Science, 1995
We have investigated the interaction of oxygen with Ag(lll) by using a supersonic molecular beam in the impact energy range 93-800 meV. At 105 K, contrary to the results of Carley et al. [Surf. Sci. 238 (1990) L467], we find no evidence for O 2 adsorption even after very high O 2 exposures (~ 25000 L) indicating that for a clean surface the sticking probability S is lower than 6 X 10 -7 for the whole impact energy range. At room temperature dissociative oxygen adsorption occurs at E i = 0.80 eV, with S = 9 x 10 -7. The data show however evidence that the adsorption process is mediated also in this case by adsorbed OH so that S is even smaller for the clean surface.
Co-adsorption of ethylene and oxygen on the Ag(001) surface
Surface Science, 2003
The adsorption of ethylene on clean and atomic-oxygen pre-covered Ag(0 0 1) surfaces was studied using densityfunctional theory. We find that ethylene binds rather weakly to both clean and oxygen pre-covered Ag(0 0 1) surfaces and that the molecular geometry is correspondingly almost unchanged upon adsorption. Our results indicate that the chemisorption energy increases considerably if subsurface oxygen is present, and this is correlated with a stronger hybridization between the silver d and ethylene p à states.