A Refined Leed Analysis of Water on Ru{0001}: An Experimental Test of the Partial Dissociation Model

Puisto, S. R.; Lerotholi, T. J.; Held, Georg; Menzel, D.

doi:10.1142/s0218625x03005086

Cited by 40 publications

(49 citation statements)

References 14 publications

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“…73,75 The weak intensity of OD ͑dangling OD͒ on Ru͑0001͒ at D 2 O Ͻ 1.0 ML has also been observed in sumfrequency generation measurement 76 and by IRAS measurements from the group of Haq et al 49 as well as our group. 77 Based on density functional theory, IRAS measurements, low energy electron diffraction results, TPD, and work function measurements in literature, the group of Haq et al has recently proposed 49 chains of intact water as the structure of the first layer on Ru͑0001͒, which is different from bulk icelike structure, dissociated phase ͑OD+D 2 O phase͒, 41,42 and previously proposed first layer models 35,[40][41][42][43][44][45][46][47][48] but agrees well with most of the experimental observations up to now.…”

Section: O On Ru"0001…supporting

confidence: 63%

Deposition and crystallization studies of thin amorphous solid water films on Ru(0001) and on CO-precovered Ru(0001)

Kondo

Kato

Bonn

et al. 2007

The Journal of Chemical Physics

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The deposition and the isothermal crystallization kinetics of thin amorphous solid water ͑ASW͒ films on both Ru͑0001͒ and CO-precovered Ru͑0001͒ have been investigated in real time by simultaneously employing helium atom scattering, infrared reflection absorption spectroscopy, and isothermal temperature-programmed desorption. During ASW deposition, the interaction between water and the substrate depends critically on the amount of preadsorbed CO. However, the mechanism and kinetics of the crystallization of ϳ50 layers thick ASW film were found to be independent of the amount of preadsorbed CO. We demonstrate that crystallization occurs through random nucleation events in the bulk of the material, followed by homogeneous growth, for solid water on both substrates. The morphological change involving the formation of three-dimensional grains of crystalline ice results in the exposure of the water monolayer just above the substrate to the vacuum during the crystallization process on both substrates.

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Section: O On Ru"0001…supporting

confidence: 63%

Deposition and crystallization studies of thin amorphous solid water films on Ru(0001) and on CO-precovered Ru(0001)

Kondo

Kato

Bonn

et al. 2007

The Journal of Chemical Physics

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“…Our results for this structure confirmed Feibelman's [18] and Michaelides et al's [45] findings. Specifically, we obtained (i) a value of bilayer buckling and O-Ru distance considerably smaller than those of the intact bilayers, and in satisfactory agreement with the values obtained by the LEED-IV analysis [19,59], (ii) an adsorption energy ∼ 0.30 eV higher than the one for the intact bilayers, and ∼ 0.15 eV higher than the sublimation energy for ice I h . The lowering of the average bilayer distance from the surface with respect to the intact structures finds its justification in the substitution of a water molecule, which binds the surface via long-range non-bonding interactions, with an OH radical, binding the surface through a real chemical bond [45].…”

Section: Water Adsorption On Ru(0001)supporting

confidence: 86%

“…Note that now the first layer is made of OH radicals and the second of intact molecules and that both the H 2 O molecule and the OH radical lie almost flat, with their dipole moment directed out of the surface. Also, the buckling of the Ru atoms underlying the two oxygen atoms is significantly smaller than in the intact bilayers, and than its experimental value [59]. The change in adsorption energy from the intact to the half-dissociated bilayer structures is not only due to the dissociation of an adsorbed water molecule but also due to the considerable approaching of the remaining undissociated water molecule to the surface.…”

Section: Water Adsorption On Ru(0001)mentioning

confidence: 75%

“…We have also investigated an alternative halfdissociated structure [18,45,59] where the dissociated hydrogens are removed from their on-top positions at the center of the hexagons and let adsorb at fcc sites [60] in a separate p( √ 3× √ 3) R30 • cell. Although, as pointed out in Ref.…”

Section: Water Adsorption On Ru(0001)mentioning

confidence: 99%

“…[45], the existence of such system depends both on the presence of clean patches of Ru(0001) surface and on the ease of H diffusion throughout the halfdissociated bilayer, the recent LEED analysis of Puisto et al [59] had given a considerable hint in favor of it. We did not find significant differences with the original Feibelman's model as what concerns the bilayer buckling and O-Ru distance [18,45,59], but we found some differences in the total Ru buckling, which turned out smaller than the one in the previously analyzed halfdissociated structure, and also than the value of the bestfit LEED geometry [59]. Another considerable difference was in the adsorption energy, that was ∼0.30 eV greater than the one obtained by placing H at the center of the hexagons, probably due to the higher adsorption energy of H at the fcc sites with respect to on-top sites on Ru(0001) [60].…”

Section: Water Adsorption On Ru(0001)mentioning

confidence: 99%

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Chemistry at surfaces: from ab initio structures to quantum dynamics

et al. 2007

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Recent years have witnessed an ever growing interest in theoretically studying chemical processes at surfaces. Apart from the interest in catalysis, electrochemistry, hydrogen economy, green chemistry, atmospheric and interstellar chemistry, theoretical understanding of the molecule-surface chemical bonding and of the microscopic dynamics of adsorption and reaction of adsorbates are of fundamental importance for modeling known processes, understanding new experimental data, predicting new phenomena, controlling reaction pathways. In this work, we review the efforts we have made in the last few years in this exciting field. We first consider the energetics and the structural properties of some adsorbates on metal surfaces, as deduced by converged, first-principles, plane-wave calculations within the slab-supercell approach. These studies comprise water adsorption on Ru(0001), a subject of very intense debate in the past few years, and oxygen adsorption on aluminum, the prototypical example of metal passivation. Next, we address dynamical processes at surfaces with classical and quantum methods. Here the main interest is in hydrogen dynamics on metallic and semi-metallic surfaces, because of its importance for hydrogen storage and interstellar chem- istry. Hydrogen sticking is studied with classical and quasi-classical means, with particular emphasis on the relaxation of hot-atoms following dissociative chemisorption. Hot atoms dynamics on metal surfaces is investigated in the reverse, hydrogen recombination process and compared to Eley-Rideal dynamics. Finally, Eley-Rideal, collision-induced desorption, and adsorbate-induced trapping are studied quantum mechanically on a graphite surface, and unexpected quantum effects are observed.

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Acidic Water Monolayer on Ruthenium(0001)

et al. 2012

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The ubiquity of water in natural environments makes the interaction of water with solid surfaces an important subject of study in a wide variety of scientific disciplines and technologies. [1] One of the most intensively investigated systems for the interaction of water with metal surfaces is water on Ru(0001), which has become a test system for our understanding of this scientific field. [1,2] Numerous experimental [2a-o] and theoretical studies [2h,p-x] conducted during the past decade have greatly improved our understanding of the structure and dynamics of water adsorption on Ru(0001). These studies have reached the consensus [1c] that water adsorption leads to the formation of an intact molecularwater layer on the surface at low temperature (less than about 155 K). As the surface is heated, H 2 O partially dissociates to form a mixed OH + H 2 O + H adsorption layer, in competition with desorption of H 2 O. On the other hand, D 2 O does not dissociate on the surface and desorbs intact due to a kinetic isotope effect. Despite the wealth of theoretical and experimental research on this system, there are still many open questions, in particular concerning the acid-base properties of adsorbed water. This information is fundamentally important to heterogeneous catalysis, corrosion, and electrochemistry because it determines the proton transfer and acid-base characteristics of the water-solid interface. Therefore, it is highly desirable to investigate these properties for adsorbed water using a systematic surface science approach; this could be one way to unravel the intricacies of the acid-base chemistry at water-solid interfaces. In the present work, we study the proton-transfer ability of water molecules adsorbed on a Ru(0001) surface by using surface spectroscopic measurements and ammonia adsorption experiments. The study shows that the first monolayer of water is much more acidic than bulk water, with the ability to spontaneously transfer a proton to an ammonia molecule.We prepared a water layer on Ru(0001) in ultrahigh vacuum (UHV) by the adsorption of H 2 O vapor at 140 K to a monolayer saturation coverage, a condition that is known to produce an intact molecular-water layer on the surface. [1c] Then, NH 3 was adsorbed onto the H 2 O monolayer surface for a small coverage [0.04 ML; 1 ML = 1.14 10 15 molecules cm À2 corresponding to the monolayer density of water on Ru-(0001)]. The NH 3 molecules served as a probe for the surface acidity. Figure 1 shows the results of low-energy sputtering (LES) and reactive-ion scattering (RIS) measurements for the H 2 O monolayer before and after the adsorption of NH 3 .The RIS and LES methods measure neutral and ionic species, respectively, on the surface. [3] For a layer of pure H 2 O, spectrum a in Figure 1 shows the RIS signal of CsH 2 O + (m/z = 151 amu/charge), which was produced by the pickup of surface H 2 O molecules by scattering Cs + projectiles. The peak of elastically scattered Cs + ions appeared at m/z = 133. After NH 3 adsorption (spectrum b in Figure 1),...

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A Refined Leed Analysis of Water on Ru{0001}: An Experimental Test of the Partial Dissociation Model

Cited by 40 publications

References 14 publications

Deposition and crystallization studies of thin amorphous solid water films on Ru(0001) and on CO-precovered Ru(0001)

Deposition and crystallization studies of thin amorphous solid water films on Ru(0001) and on CO-precovered Ru(0001)

Chemistry at surfaces: from ab initio structures to quantum dynamics

Acidic Water Monolayer on Ruthenium(0001)

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