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| 2. |
- Archfield, Stacey A., et al.
(författare)
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Accelerating advances in continental domain hydrologic modeling
- 2015
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Ingår i: Water resources research. - 0043-1397 .- 1944-7973. ; 51:12, s. 10078-10091
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Tidskriftsartikel (refereegranskat)abstract
- In the past, hydrologic modeling of surface water resources has mainly focused on simulating the hydrologic cycle at local to regional catchment modeling domains. There now exists a level of maturity among the catchment, global water security, and land surface modeling communities such that these communities are converging toward continental domain hydrologic models. This commentary, written from a catchment hydrology community perspective, provides a review of progress in each community toward this achievement, identifies common challenges the communities face, and details immediate and specific areas in which these communities can mutually benefit one another from the convergence of their research perspectives. Those include: (1) creating new incentives and infrastructure to report and share model inputs, outputs, and parameters in data services and open access, machine-independent formats for model replication or reanalysis; (2) ensuring that hydrologic models have: sufficient complexity to represent the dominant physical processes and adequate representation of anthropogenic impacts on the terrestrial water cycle, a process-based approach to model parameter estimation, and appropriate parameterizations to represent large-scale fluxes and scaling behavior; (3) maintaining a balance between model complexity and data availability as well as uncertainties; and (4) quantifying and communicating significant advancements toward these modeling goals.
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| 5. |
- Goriachko, A., et al.
(författare)
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Hexagonal C and BN superstructures on Ru(0001) and Ge(111)
- 2013
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Ingår i: Materialwissenschaft und Werkstofftechnik. - : Wiley. - 0933-5137. ; 44:2-3, s. 129-135
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Tidskriftsartikel (refereegranskat)abstract
- A brief overview of hexagonal superstructures with a periodicity of similar to 3 nm formed on Ru(0001) and Ge(111) by graphene or hexagonal boron nitride with a thickness of just a single atomic layer is given. A periodic height corrugation of such layers due to the lattice mismatch with the substrate material is of the order of 0.1 nm. Selected examples of scanning tunneling microscopy (STM) and low energy electron microscopy/diffraction (LEEM/LEED) investigations of BN/Ru(0001), C/Ru(0001), (BN)(x)C-y/Ru(0001) and C/Ge(111) are presented. These systems can act as nanotemplates for metal nanoparticles growth, as well as strongly heterogeneous substrates for molecular adsorption.
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| 6. |
- Goriachko, A., et al.
(författare)
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Oxygen-etching of h-BN/Ru(0001) nanomesh on the nano- and mesoscopic scale
- 2008
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Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 112:28, s. 10423-10427
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Tidskriftsartikel (refereegranskat)abstract
- The stability of the recently discovered b-BN/Ru(0001) nanomesh is of crucial importance for potential applications as a nanotemplate. In particular, thermal stability in oxygen environment is important for nanocatalysis applications. We report here on the etching experiments of the h-BN layer by molecular oxygen exposure at elevated temperatures. This process is studied both by scanning tunneling microscopy (STM) on a microscopic scale and with in situ low energy electron microscopy (LEEM) on the mesoscopic scale. Temperature thresholds are determined for the microscopic (600 degrees C) and the mesoscopic (750 degrees C) etching processes for O-2 pressures up to 1 x 10(-6) mbar. Submonolayer amounts of An deposited on the h-BN/Ru(0001) nanomesh improve considerably the stability of the h-BN nanomesh against etching by O-2.
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| 7. |
- He, YB, et al.
(författare)
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Ru(0001) model catalyst under oxidizing and reducing reaction conditions: in-situ high-pressure surface X-ray diffraction study
- 2005
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Ingår i: The Journal of Physical Chemistry Part B. - : American Chemical Society (ACS). - 1520-5207 .- 1520-6106. ; 109:46, s. 21825-21830
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Tidskriftsartikel (refereegranskat)abstract
- With surface X-ray diffraction (SXRD) using a high-pressure reaction chamber we investigated in-situ the oxidation of the Ru(0001) model catalyst under various reaction conditions, starting from a strongly oxidizing environment to reaction conditions typical for CO oxidation. With a mixture Of O-2 and CO (stoichiometry, 2:1) the partial pressure of oxygen has to be increased to 20 mbar to form the catalytically active RuO2(110) oxide film, while in pure oxygen environment a pressure of 10(-5) mbar is already sufficient to oxidize the Ru(0001) surface. For preparation temperatures in the range of 550-630 K a self-limiting RUO2(110) film is produced with a thickness of 1.6 nm. The RuO2(110) film grows self-acceleratedly after an induction period. The RuO2 films on Ru(0001) can readily be reduced by H-2 and CO exposures at 415 K, without an induction period.
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| 8. |
- Knapp, M., et al.
(författare)
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Complex interaction of hydrogen with the RuO2(110) surface
- 2007
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Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 111:14, s. 5363-5373
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Tidskriftsartikel (refereegranskat)abstract
- Using a variety of dedicated surface sensitive techniques, we studied the interaction of hydrogen with bare and adsorbate modified RuO2(110) surfaces on the atomic scale. Hydrogen interacts strongly with the undercoordinated O atoms, thereby forming hydroxyl groups and passivating available oxygen species on the oxide surface, for instance, for the catalytic CO oxidation reaction. Temperature programmed reaction and desorption elucidate the complex reaction behavior of hydrogen with O precovered RuO2(110), including the hydrogen transfer reaction between the different kinds of undercoordinated surface oxygen atoms. Hydroxyl, water species, and hydrogen transfer are identified with high-resolution O1s core level spectroscopy by comparison with density functional theory (DFT) calculated O1s core level shifts. DFT calculations provide adsorption energies, atomic geometries, as well as diffusion barriers of H atoms on the RuO2(110) surface.
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| 9. |
- Knapp, M., et al.
(författare)
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Unusual process of water formation on RuO2(110) by hydrogen exposure at room temperature
- 2006
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Ingår i: The Journal of Physical Chemistry Part B. - : American Chemical Society (ACS). - 1520-5207 .- 1520-6106. ; 110:29, s. 14007-14010
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Tidskriftsartikel (refereegranskat)abstract
- The reduction mechanism of the RuO2(110) surface by molecular hydrogen exposure is unraveled to an unprecedented level by a combination of temperature programmed reaction, scanning tunneling microscopy, high-resolution core level shift spectroscopy, and density functional theory calculations. We demonstrate that even at room temperature hydrogen exposure to the RuO2(110) surface leads to the formation of water. In a two-step process, hydrogen saturates first the bridging oxygen atoms to form (O-br-H) species and subsequently part of these O-br-H groups move to the undercoordinated Ru atoms where they form adsorbed water. This latter process is driven by thermodynamics leaving vacancies in the bridging O rows.
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| 10. |
- Over, H., et al.
(författare)
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Direct comparison of the reactivity of the non-oxidic phase of Ru(0001) and the RuO2 phase in the Co oxidation reaction
- 2009
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Ingår i: Surface Science. - : Elsevier BV. - 0039-6028. ; 603:2, s. 298-303
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Tidskriftsartikel (refereegranskat)abstract
- Applying in situ surface X-ray diffraction (SXRD) together with on-line mass spectrometry during the CO oxidation over Ru(0001) allows a direct comparison of the reactivity of the non-oxidic state with that of the RuO2(110) covered surface. This comparison reveals that the RuO2(110) surface is a catalytically active phase at least as active as the non-oxidic phase. At high CO and O-2 pressures of 200 mbar and temperatures above 550 K, the CO oxidation reaction does not proceed isothermally on the RuO2(110) surface. The released reaction heat leads rather to an increase of the sample temperature of up to 130 K accompanied by a self-acceleration of the CO oxidation reaction. (C) 2008 Elsevier B.V. All rights reserved.
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