Coadsorption of cesium and water on MgO(100)

Karolewski, M.A.; Cavell, Ronald G.

doi:10.1016/0039-6028(92)90867-6

Cited by 28 publications

(15 citation statements)

References 36 publications

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“…The extensive number of experimental ,,,− ,− ,− and theoretical studies − ,,,,,,− that probed the structure and reactivity of MgO (100) and the chemistry of water on MgO illustrates the complexity of this “simple” system. Empirical observations of molecular adsorption and chemidissociation vary depending on the experimental method used, sample preparation, and measurement conditions.…”

Section: 2 Example Applications721 Hydroxylation Of Mgo (100) and Cao...mentioning

confidence: 99%

Metal Oxide Surfaces and Their Interactions with Aqueous Solutions and Microbial Organisms

et al. 1998

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Section: 2 Example Applications721 Hydroxylation Of Mgo (100) and Cao...mentioning

confidence: 99%

Metal Oxide Surfaces and Their Interactions with Aqueous Solutions and Microbial Organisms

et al. 1998

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“…This procedure is sufficient to desorb any adsorbed hydrogen. [9][10][11] After cooling, Augerelectron spectra ͑AES͒ were taken, which showed a KLL carbon peak equivalent to 6% of 1 monolayer.…”

Section: Sample Preparationmentioning

confidence: 99%

Nanoscale Fe islands on MgO(001) produced by molecular-beam epitaxy

et al. 1999

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We report that a 10-nm thick Fe film grown at an elevated temperature on MgO͑001͒ forms isolated islands of diameter between 10 and 100 nm. Increasing the deposition temperature causes the islands to decrease in diameter. The resulting films are electrically insulating but show electrical transport properties that vary strongly with growth temperature when capped with 2 nm Au. Films grown at a temperature of 743 K showed a giant magnetoresistance of 0.7% when measured at room temperature. ͓S0163-1829͑99͒01012-7͔

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“…It is commonly used as a model system for understanding interfacial processes on oxide materials. Several experimental ,− and theoretical − studies have investigated the properties of the water/MgO interface. The diversity in the empirical data probing the nature of this interface indicates that MgOlike many metal oxidesis a “structure sensitive” material whose properties are very dependent on the experimental approach and sample preparation procedures used.…”

Section: Introductionmentioning

confidence: 99%

Structure and Dynamics of the Water/MgO Interface

et al. 1996

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A pairwise additive potential energy expression for the water/MgO interaction was obtained by fitting the parameters to ab initio electronic structure energy data, computed using correlation-corrected periodic HartreeFock (PHF) theory, at selected adsorbate/surface geometries. This potential energy expression was used in molecular dynamics and Monte Carlo simulations to elucidate the water/MgO interaction. Energy minimization reveals a nearly planar adsorbate/surface equilibrium geometry (-15°from the surface plane with the hydrogens pointing toward the surface oxygens) for an isolated water on perfect MgO (001), with a binding energy of 17.5 kcal/mol; subsequent PHF calculations on this system confirmed that this is a potential minimum. Rate constants for desorption (k dsorb ), intersite hopping (k hop ), intrasite rotation (k rot ), and intrasite flipping (k flip ) were estimated for an isolated water on the surface using simple transition state theory. The computed rates (at T ) 300 K) are k dsorb ) 1.1 × 10 5 s -1 , k hop ) 3.7 × 10 10 s -1 , k rot ) 5.7 × 10 11 s -1 , and k flip ) 4.6 × 10 11 s -1 . The motion of a single water on the surface is described by an effective diffusion constant (D eff ) 8.0 × 10 -6 cm 2 /s), computed from the surface rate constants combined with Monte Carlo simulations. The structure of the liquid water/MgO interface was determined from simulations with 64 and 128 water molecules on the surface. Simulations (at T ) 300 K) of the two-dimensional water overlayers reveal a densely packed first layer, Z(O w -surf) ) 2-3 Å, with one water per surface magnesium, with a nearly equal distribution of water molecules aligned -17°and +30°with respect to the surface plane. A more diffuse second layer exists, Z(O w -surf) ) 4-5.5 Å, with a much broader distribution of water angular orientations with respect to the surface plane. The region Z(O w -surf) > 6 Å resembles bulk water, with the density profile approaching a constant as a function of distance above the surface and a uniform distribution in water/surface angular orientations. At the water/vacuum interface (top of the multilayer) the waters assume a "planar orientation" (0°with respect to the surface plane). During the timescale of these simulations very little interlayer exchange of water molecules occurs between the first monolayer (n ) 1) and the additional overlayers (n g 2). In contrast, the water molecules in the multilayers (n g 2) display motion similar to bulk liquid water at this temperature.

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Coadsorption of cesium and water on MgO(100)

Cited by 28 publications

References 36 publications

Metal Oxide Surfaces and Their Interactions with Aqueous Solutions and Microbial Organisms

Metal Oxide Surfaces and Their Interactions with Aqueous Solutions and Microbial Organisms

Nanoscale Fe islands on MgO(001) produced by molecular-beam epitaxy

Structure and Dynamics of the Water/MgO Interface

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