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Showing 1 to 20 of 56 for “"chemisorbed"”.
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Probing the Surface of a Heterogeneous Catalyst: Double Resonance of Carbon Monoxide Chemisorbed on Highly Dispersed Platinum
… 77 K for small Pt particles on which ('13)CO was chemisorbed. The samples are Pt supported on eta-alumina with Pt dispersions (fraction of the atoms that are on the surface) of 26% and 76%. After cleaning, the samples are exposed to CO enriched to 90% ('13)C. The ('13)C NMR is observed indirectly …
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Probing the surface of a heterogeneous catalyst: Double resonance of carbon monoxide chemisorbed on highly dispersed platinum
… at 77 K for small Pt particles on which l3CO was chemisorbed. The samples are Pt supported on eta-alumina with Pt dispersions (fraction of the atoms that are on the surface) of 26% and 76%. After cleaning, the samples are exposed to CO enriched to 90% l3C• The l3C NMR is observed indirectly …
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A new approach to the study of surface phenomena, measurements of diffusion rates, intermolecular distances and electronic properties of CO chemisorbed on supported platinum catalysts by nuclear magnetic resonance
… are consistent with the geometry of CO layers chemisorbed on single crystal surfaces. He has observed the narrowing of the NMR line and the effects of motion on transverse relaxation from 300 K to 600 K from which he deduces diffusion energies of 13 and 16 plus/minus 2 kcal/mol, in agreement …
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Diffusion and Evaporation of Nitrogen on Tungsten (100)
… and evaporation from a layer of nitrogen chemisorbed on the (100) plane of tungsten has been examined using Auger spectroscopy. The initial localized deposit required for diffusion measurements in a concentration gradient is created by a highly collimated molecular beam. The sample, under …
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A New Approach to the Study of Surface Phenomena: Measurements of Diffusion Rates, Intermolecular Distances and Electronic Properties of Carbon Monoxide Chemisorbed on Supported Platinum Catalysts by Nuclear Magnetic Resonance
The author has applied magnetic resonance to study the chemisorption of CO on supported platinum particles. The particles are 10 to 50 (ANGSTROM) in diameter, supported on alumina. CO is 90% enriched with ('13)CO. NMR data were taken from 4 K to 600 K.
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Nuclear magnetic resonance study of the bonding of carbon monoxide to palladium and platinum surfaces
The 13c and 17o NMR of CO chemisorbed on small particles of Pd and Pt has been observed. The 17o resonance represents the first reported NMR observation of a spin larger than 1/2 adsorbed on a metal surface. At low temperatures, the 13c resonance of CO on Pd is centered at 540 ppm down field from …
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Nuclear Magnetic Resonance Study of the Bonding of Carbon-Monoxide to Palladium and Platinum Surfaces (Nmr)
The ('13)C and ('17)O NMR of CO chemisorbed on small particles of Pd and Pt has been observed. The ('17)O resonance represents the first reported NMR observation of a spin larger than 1/2 adsorbed on a metal surface.
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Relation between surface structural and chemical properties of platinum nanoparticles and their catalytic activity in the decomposition of hydrogen peroxide
… samples have different particle size and surface chemisorbed oxygen abundance, which were varied further by pretreating both samples at variable conditions. The rate of H₂O₂ decomposition was studied systematically as a function of H₂O₂ concentration, pH, temperature, particle size and surface …
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Chelate Assisted, Pressurized, Liquid Extraction for the Removal of Adsorbed Metal Contaminants From Soils
… CAPLE could be optimized to completely remove chemisorbed metals. Tests of CAPLE on Cu-sludge amended soils provided excellent agreement with traditional methods of soil analysis. Not only was good agreement obtained between the recoveries of the methods, but CAPLE was also found to be much …
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Theoretical investigation of polar zinc oxide surface modification via phosphonic acid self-assembled monolayers
… polar zinc oxide surface (0002) with a series of chemisorbed fluorinated benzylphosphonic acids has been studied using density functional theory. The calculations indicate that there is a substantial change in the binding energies and work function modification depending on the binding motif. The …
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Nonstoichiometry of chalcocite in water-xanthate systems
… a nonstoichiometric copper sulfide near 0 mV. Chemisorbed xanthate formed at -295 mV which correlated well with the lower flotation edge determined in this and other studies. The standard free energy of the chemisorbed xanthate was determined to be -13.08 kcal/mole.
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Orientation and chemistry of alkoxides on copper(111)
… alcohols deprotonate to form stable alkoxides chemisorbed to the surface. These alkoxides decompose at elevated temperatures by $\beta$-hydride elimination, desorbing as aldehydes. The influence of deuterium isotope labelling, selective fluorination, and chain length on this mechanism has been …
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Density functional theory investigations of graphene-based heterostructures
… that hBN/Ni has two configurational minima, one chemisorbed and one physisorbed, whose properties are not altered when graphene is placed atop hBN. However, a switch from chemisorbed to physisorbed hBN on Ni can occur due to the processing conditions during graphene growth; this switch is solely …
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Control of Surface Chemistry of Gold, Pyrite and Pyrrhotite
… species that renders the surface hydrophobic. Chemisorbed xanthate is observed on the gold surface but is hydrophilic. The synthetic polymers may adsorb on pyrite and pyrrhotite possibly through the hydrophobic interaction between the hydrophobic moiety of the polymer and the mineral surface …
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The Effect of Substrate Parameters on the Morphology of Thermally Sprayed PEEK Splats
… area associated with low levels of hydroxide and chemisorbed water on the aluminium surface. Substrates held at 323°C were more sensitive to substrate morphology, where rough surfaces resulted in decreased circularity and area apparently independent of surface chemistry. Substrate temperature …
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Studies of Structure and Reactivity in Monolayer Assemblies: 1. Ozonolysis of Alkanethiolate Self Assembled Monolayers on Au. 2. In-Plane Resistivity of Ultrathin Gold Films as a High Sensitivity, Molecularly Differentiated Probe of Chemisorption at the Liquid-Metal Interface
… Au film thicknesses (d ∼ 40 nm), strongly chemisorbed thiolate monolayers increase the resistivity of the thin Au films by ca. 4%, but weakly adsorbed species, such as pyridine or phenolate at open circuit, induce no observable change in the Au film resistance. Resistivity measurements …
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Structural study of electrochemically induced adsorption and diffusion of metal surfaces
… cryogen, and vacuum. Unless the adsorbate is chemisorbed to the surface, the adsorbate diffuses across the surface due to thermal instability which causes difficulties in imaging. This problem can be overcome by lowering the temperature of the substrate. We have built a variable temperature …
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Kinetic studies of the reaction of gallium arsenide with molecular chlorine and iodine
… by the dissociation of the molecule into chemisorbed atoms, and finally the reaction of these atoms with the surface to yield gaseous products. The first and the half order rate constant for both reactions were determined and represented in the form of the following Arrhenius equations: …
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Formation of Silicon-Nitride Structures by Direct Electron-Beam Writing
… nitridation is the formation of a monolayer of chemisorbed nitrogen via the nucleation and lateral growth of islands.
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