C. L. R. James and the Antiguan Left

Henry, Paget

doi:10.1215/9780822382386-016

Cited by 115 publications

(172 citation statements)

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“…It is important to investigate the exact nature of the metal/oxide bond to understand not only the growth mechanism of metal clusters, but also to reveal the fundamental processes behind the catalytic activity of oxidesupported metal catalysts [5,6]. It has been speculated that surface defects may alter the electronic configuration of Au nanoparticles to enable catalytic reactions such as CO oxidation.…”

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confidence: 99%

Bonding of Gold Nanoclusters to Oxygen Vacancies on RutileTiO2(110)

et al. 2003

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Through an interplay between scanning tunneling microscopy (STM) and density functional theory (DFT) calculations, we show that bridging oxygen vacancies are the active nucleation sites for Au clusters on the rutile TiO 2 110 surface. We find that a direct correlation exists between a decrease in density of vacancies and the amount of Au deposited. From the DFT calculations we find that the oxygen vacancy is indeed the strongest Au binding site. We show both experimentally and theoretically that a single oxygen vacancy can bind 3 Au atoms on average. In view of the presented results, a new growth model for the TiO 2 110 system involving vacancy-cluster complex diffusion is presented.

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confidence: 99%

Bonding of Gold Nanoclusters to Oxygen Vacancies on RutileTiO2(110)

et al. 2003

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“…͑6͒, we obtain g = 2⍀a 2 g 3 3k B TL 3 , ͑C6͒ which can be calculated using the values in Table I. The atomic volume is calculated as ⍀ = a 3 .…”

Section: Appendix C: Materials Parametersmentioning

confidence: 99%

“…2 However, characterizing the morphology of nanoscale structures is still a challenging problem and our ability to control their evolution is fairly limited. 3 As fabricated structures become smaller, finite-size effects associated with the crystal's geometry become more important. The steps that bound each monolayer in the structure are usually closed and have a finite radius of curvature.…”

Section: Introductionmentioning

confidence: 99%

Facet evolution on supported nanostructures: Effect of finite height

2008

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The surface of a nanostructure relaxing on a substrate consists of a finite number of interacting steps and often involves the expansion of facets. Prior theoretical studies of facet evolution have focused on models with an infinite number of steps, which neglect edge effects caused by the presence of the substrate. By considering diffusion of adsorbed atoms ͑adatoms͒ on terraces and attachment-detachment of atoms at steps, we show that these edge or finite height effects play an important role in the structure's macroscopic evolution. We assume diffusion-limited kinetics for adatoms and a homoepitaxial substrate. Specifically, using data from step simulations and a continuum theory, we demonstrate a switch in the time behavior of geometric quantities associated with facets: the facet edge position in a straight-step system and the facet radius of an axisymmetric structure. Our analysis and numerical simulations focus on two corresponding model systems where steps repel each other through entropic and elastic dipolar interactions. The first model is a vicinal surface consisting of a finite number of straight steps; for an initially uniform step train, the slope of the surface evolves symmetrically about the centerline, i.e., the middle step when the number of steps is odd. The second model is an axisymmetric structure consisting of a finite number of circular steps; in this case, we include curvature effects which cause steps to collapse under the effect of line tension. In the first case, we show that the position of the facet edge, measured from the centerline, switches from O͑t 1/4 ͒ behavior to O͑t 1/5 ͒ ͑where t is time͒. In the second case, the facet radius switches from O͑t 1/4 ͒ to O͑t͒. For the axisymmetric case, we also predict analytically through a continuum shock wave theory how the individual collapse times are modified by the effects of finite height under the assumption that step interactions are weak compared to the step line tension.

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“…[1][2][3][4][5] Despite a general acceptance that the rough features play a crucial role, the exact nature of the enhancement is not well understood. [6][7][8] Recent experimental studies for hydrogen reacting on the Pt͑533͒ surface have been enlightening as regards the mechanisms occurring in the dissociation of molecules on stepped surfaces.…”

Section: Introductionmentioning

confidence: 99%

Away from generalized gradient approximation: Orbital-dependent exchange-correlation functionals

Baerends¹,

Gritsenko

2005

The Journal of Chemical Physics

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Rotational effects in the dissociative adsorption of H 2 on the Pt͑211͒ stepped surface have been studied using classical trajectory calculations on a six-dimensional, density-functional theory potential-energy surface. Reaction of rotating molecules via an indirect trapping mechanism exhibits an unexpected nonmonotonic dependence on the initial rotational quantum number J. Indirect reaction is first quenched with increasing J but is enhanced again for high J initial states. The quenching is attributed to rotational-to-translational energy transfer, which facilitates escape from the chemisorption wells responsible for molecular trapping. For high J, rotational and translational motions decouple, and the energy transfer is no longer possible, which leads again to trapping. Degeneracy-resolved calculations show that for high initial J, molecules rotating in a "cartwheel" fashion ͑m J =0͒ are more likely to become trapped and react indirectly than "helicoptering" molecules ͑m J = J͒. Experimental confirmation of this finding would lend strong support to the existence of the chemisorption wells that trap molecules prior to reaction.

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C. L. R. James and the Antiguan Left

Cited by 115 publications

References 0 publications

Bonding of Gold Nanoclusters to Oxygen Vacancies on RutileTiO2(110)

Bonding of Gold Nanoclusters to Oxygen Vacancies on RutileTiO2(110)

Facet evolution on supported nanostructures: Effect of finite height

Away from generalized gradient approximation: Orbital-dependent exchange-correlation functionals

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