| 1. |
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| 2. |
- Armesto, N., et al.
(author)
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Heavy-ion collisions at the LHC-Last call for predictions
- 2008
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In: Journal of Physics G. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 35:5, s. 054001-
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Research review (peer-reviewed)abstract
- This writeup is a compilation of the predictions for the forthcoming Heavy Ion Program at the Large Hadron Collider, as presented at the CERN Theory Institute 'Heavy Ion Collisions at the LHC - Last Call for Predictions', held from 14th May to 10th June 2007.
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| 3. |
- Bluhm, P., et al.
(author)
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Precise mass and radius of a transiting super-Earth planet orbiting the M dwarf TOI-1235: a planet in the radius gap?
- 2020
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In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 639
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Journal article (peer-reviewed)abstract
- We report the confirmation of a transiting planet around the bright weakly active M0.5 V star TOI-1235 (TYC 4384-1735-1, V ≈ 11.5 mag), whose transit signal was detected in the photometric time series of sectors 14, 20, and 21 of the TESS space mission. We confirm the planetary nature of the transit signal, which has a period of 3.44 d, by using precise RV measurements with the CARMENES, HARPS-N, and iSHELL spectrographs, supplemented by high-resolution imaging and ground-based photometry. A comparison of the properties derived for TOI-1235 b with theoretical models reveals that the planet has a rocky composition, with a bulk density slightly higher than that of Earth. In particular, we measure a mass of Mp = 5.9 ± 0.6 M⊕ and a radius of Rp = 1.69 ± 0.08 R⊕, which together result in a density of ρp = 6.7- 1.1+ 1.3 g cm-3. When compared with other well-characterized exoplanetary systems, the particular combination of planetary radius and mass places our discovery in the radius gap, which is a transition region between rocky planets and planets with significant atmospheric envelopes. A few examples of planets occupying the radius gap are known to date. While the exact location of the radius gap for M dwarfs is still a matter of debate, our results constrain it to be located at around 1.7 R⊕ or larger at the insolation levels received by TOI-1235 b (~60 S⊕). This makes it an extremely interesting object for further studies of planet formation and atmospheric evolution.
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| 4. |
- Sunn Pedersen, Thomas, et al.
(author)
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Experimental confirmation of efficient island divertor operation and successful neoclassical transport optimization in Wendelstein 7-X
- 2022
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In: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 62:4, s. 042022-042022
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Journal article (peer-reviewed)abstract
- We present recent highlights from the most recent operation phases of Wendelstein 7-X, the most advanced stellarator in the world. Stable detachment with good particle exhaust, low impurity content, and energy confinement times exceeding 100 ms, have been maintained for tens of seconds. Pellet fueling allows for plasma phases with reduced ion-temperature-gradient turbulence, and during such phases, the overall confinement is so good (energy confinement times often exceeding 200 ms) that the attained density and temperature profiles would not have been possible in less optimized devices, since they would have had neoclassical transport losses exceeding the heating applied in W7-X. This provides proof that the reduction of neoclassical transport through magnetic field optimization is successful. W7-X plasmas generally show good impurity screening and high plasma purity, but there is evidence of longer impurity confinement times during turbulence-suppressed phases.
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| 5. |
- Chaturvedi, P., et al.
(author)
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TOI-1468: A system of two transiting planets, a super-Earth and a mini-Neptune, on opposite sides of the radius valley
- 2022
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In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 666
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Journal article (peer-reviewed)abstract
- We report the discovery and characterization of two small transiting planets orbiting the bright M3.0V star TOI-1468 (LSPM J0106+1913), whose transit signals were detected in the photometric time series in three sectors of the TESS mission. We confirm the planetary nature of both of them using precise radial velocity measurements from the CARMENES and MAROON-X spectrographs, and supplement them with ground-based transit photometry. A joint analysis of all these data reveals that the shorter-period planet, TOI-1468 b (P-b = 1.88 d), has a planetary mass of M-b = 3.21 +/- 0.24M(circle plus) and a radius of R-b = 1.280(-0.039)(+0.038) R-circle plus, resulting in a density of rho(b) = 8.39(-0.92)(+1.05) g cm(-3), which is consistent with a mostly rocky composition. For the outer planet, TOI-1468 c (P-c = 15.53 d), we derive a mass of M-c = 6.64(-0.68)(+0.67) M-circle plus,aradius of R-c = 2.06 +/- 0.04 R-circle plus, and a bulk density of rho(c) = 2.00(-0.19)(+0.21) g cm(-3), which corresponds to a rocky core composition with a H/He gas envelope. These planets are located on opposite sides of the radius valley, making our system an interesting discovery as there are only a handful of other systems with the same properties. This discovery can further help determine a more precise location of the radius valley for small planets around M dwarfs and, therefore, shed more light on planet formation and evolution scenarios.
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| 6. |
- Bartels-Rausch, T., et al.
(author)
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A review of air-ice chemical and physical interactions (AICI): Liquids, quasi-liquids, and solids in snow
- 2014
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In: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 14:3, s. 1587-1633
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Journal article (peer-reviewed)abstract
- Snow in the environment acts as a host to rich chemistry and provides a matrix for physical exchange of contaminants within the ecosystem. The goal of this review is to summarise the current state of knowledge of physical processes and chemical reactivity in surface snow with relevance to polar regions. It focuses on a description of impurities in distinct compartments present in surface snow, such as snow crystals, grain boundaries, crystal surfaces, and liquid parts. It emphasises the microscopic description of the ice surface and its link with the environment. Distinct differences between the disordered air-ice interface, often termed quasi-liquid layer, and a liquid phase are highlighted. The reactivity in these different compartments of surface snow is discussed using many experimental studies, simulations, and selected snow models from the molecular to the macro-scale. Although new experimental techniques have extended our knowledge of the surface properties of ice and their impact on some single reactions and processes, others occurring on, at or within snow grains remain unquantified. The presence of liquid or liquid-like compartments either due to the formation of brine or disorder at surfaces of snow crystals below the freezing point may strongly modify reaction rates. Therefore, future experiments should include a detailed characterisation of the surface properties of the ice matrices. A further point that remains largely unresolved is the distribution of impurities between the different domains of the condensed phase inside the snowpack, i.e. in the bulk solid, in liquid at the surface or trapped in confined pockets within or between grains, or at the surface. While surface-sensitive laboratory techniques may in the future help to resolve this point for equilibrium conditions, additional uncertainty for the environmental snowpack may be caused by the highly dynamic nature of the snowpack due to the fast metamorphism occurring under certain environmental conditions. Due to these gaps in knowledge the first snow chemistry models have attempted to reproduce certain processes like the long-term incorporation of volatile compounds in snow and firn or the release of reactive species from the snowpack. Although so far none of the models offers a coupled approach of physical and chemical processes or a detailed representation of the different compartments, they have successfully been used to reproduce some field experiments. A fully coupled snow chemistry and physics model remains to be developed. © Author(s) 2014.
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| 7. |
- Ma, Li-Jun, et al.
(author)
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Comparative genomics reveals mobile pathogenicity chromosomes in Fusarium.
- 2010
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In: Nature. - : Springer Science and Business Media LLC. - 1476-4687 .- 0028-0836. ; 464:7287, s. 367-73
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Journal article (peer-reviewed)abstract
- Fusarium species are among the most important phytopathogenic and toxigenic fungi. To understand the molecular underpinnings of pathogenicity in the genus Fusarium, we compared the genomes of three phenotypically diverse species: Fusarium graminearum, Fusarium verticillioides and Fusarium oxysporum f. sp. lycopersici. Our analysis revealed lineage-specific (LS) genomic regions in F. oxysporum that include four entire chromosomes and account for more than one-quarter of the genome. LS regions are rich in transposons and genes with distinct evolutionary profiles but related to pathogenicity, indicative of horizontal acquisition. Experimentally, we demonstrate the transfer of two LS chromosomes between strains of F. oxysporum, converting a non-pathogenic strain into a pathogen. Transfer of LS chromosomes between otherwise genetically isolated strains explains the polyphyletic origin of host specificity and the emergence of new pathogenic lineages in F. oxysporum. These findings put the evolution of fungal pathogenicity into a new perspective.
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| 8. |
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| 10. |
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| 12. |
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| 13. |
- Nordlund, Dennis, et al.
(author)
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Probing the Electron Delocalization in Liquid Water and Ice at Attosecond Time Scales
- 2007
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In: Physical Review Letters. - : American Physical Society. - 1079-7114 .- 0031-9007. ; 99, s. 217406-
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Journal article (peer-reviewed)abstract
- We determine electron delocalization rates in liquid water and ice using core-hole decay spectroscopy. The hydrogen-bonded network delocalizes the electrons in less than 500 as. Broken or weak hydrogen bonds—in the liquid or at the surface of ice—provide states where the electron remains localized longer than 20 fs. These asymmetrically bonded water species provide electron traps, acting as a strong precursor channel to the hydrated electron.
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| 14. |
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| 16. |
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| 17. |
- Westerström, Rasmus, et al.
(author)
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Oxidation and reduction of Pd(100) and aerosol-deposited Pd nanoparticles
- 2011
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In: Physical Review B - Condensed Matter and Materials Physics. - 2469-9950 .- 2469-9969 .- 1098-0121. ; 83:11
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Journal article (peer-reviewed)abstract
- Using in situ high-pressure x-ray photoelectron spectroscopy, we have followed the oxidation and the reduction of Pd model catalysts in oxygen and CO pressures in the millibar range. The study includes a Pd(100) single crystal as well as SiOx-supported Pd nanoparticles of 15 or 35 nm diameter, respectively. We demonstrate that nanoparticles also form ultrathin surface oxides prior to the onset of the bulk PdO. The Pd nanoparticles are observed to bulk oxidize at sample temperatures 40 degrees lower than the single-crystal surface. In the Pd 3d(5/2) and the O 1s spectrum, we identify a component corresponding to undercoordinated atoms at the surface of the PdO oxide. The experimentally observed PdO core-level shift is supported by density functional theory calculations. In a CO atmosphere, the Pd 3d(5/2) component corresponding to undercoordinated PdO atoms is shifted by + 0.55 eV with respect to PdO bulk, demonstrating that CO molecules preferably adsorb at these sites. CO coordinated to Pd atoms in the metallic and the oxidized phases can also be distinguished in the C 1s spectrum. The initial reduction by CO is similar for the single-crystal and the nanoparticle samples, but after the complete removal of the oxide we detect a significant deviation between the two systems, namely that the nanoparticles incorporate carbon to form a Pd carbide. Our results indicate that CO can dissociate on the nanoparticle samples, whereas no such behavior is observed for the Pd(100) single crystal. These results demonstrate the similarities, as well as the important differences, between the single crystals used as model systems for catalysis and nm-sized particles on oxide supports.
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| 18. |
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| 19. |
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| 20. |
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| 21. |
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| 22. |
- Balmes, Olivier, et al.
(author)
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Reversible formation of a PdCx phase in Pd nanoparticles upon CO and O-2 exposure
- 2012
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In: Physical Chemistry Chemical Physics. - : Royal Society of Chemistry (RSC). - 1463-9084 .- 1463-9076. ; 14:14, s. 4796-4801
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Journal article (peer-reviewed)abstract
- The structure and chemical composition of Pd nanoparticles exposed to pure CO and mixtures of CO and O-2 at elevated temperatures have been studied in situ by a combination of X-ray Diffraction and X-ray Photoelectron Spectroscopy in pressures ranging from ultra high vacuum to 10 mbar and from room temperature to a few hundred degrees celsius. Our investigation shows that under CO exposure, above a certain temperature, carbon dissolves into the Pd particles forming a carbide phase. Upon exposure to CO and O-2 mixtures, the carbide phase forms and disappears reversibly, switching at the stoichiometric ratio for CO oxidation. This finding opens new scenarios for the understanding of catalytic oxidation of C-based molecules.
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| 23. |
- Bluhm, GL, et al.
(author)
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Road traffic noise and hypertension
- 2007
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In: Occupational and environmental medicine. - : BMJ. - 1470-7926 .- 1351-0711. ; 64:2, s. 122-126
-
Journal article (peer-reviewed)
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| 24. |
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| 25. |
- Bluhm, Marcus, et al.
(author)
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Dynamics of critical fluctuations : Theory - phenomenology - heavy-ion collisions
- 2020
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In: Nuclear Physics A. - : ELSEVIER. - 0375-9474 .- 1873-1554. ; 1003
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Journal article (peer-reviewed)abstract
- This report summarizes the presentations and discussions during the Rapid Reaction Task Force "Dynamics of critical fluctuations: Theory - phenomenology - heavy-ion collisions", which was organized by the ExtreMe Matter Institute EMMI and held at GSI, Darmstadt, Germany in April 2019. We address the current understanding of the dynamics of critical fluctuations in QCD and their measurement in heavy-ion collision experiments. In addition, we outline what might be learned from studying correlations in other physical systems, such as cold atomic gases.
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| 26. |
- Croot, P.L., et al.
(author)
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Regeneration of Fe(II) during EIFeX and SOFeX
- 2008
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In: GEOPHYSICAL RESEARCH LETTERS. ; 35
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Journal article (peer-reviewed)abstract
- Investigations into Fe(II) cycling during two Southern Ocean mesoscale iron enrichment experiments, SOFeX and EIFeX, clearly show the importance of Fe(II) to iron speciation during these experiments. In both cases the added Fe(II) persisted significantly longer than its expected oxidation time indicating a significant Fe reduction process at work. During EIFeX diel studies showed a strong photochemically induced cycle in Fe(II) production in sunlit surface waters. Our results suggest that the photochemical cycling of iron may also be important in unfertilized waters of the Southern Ocean.
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| 27. |
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| 28. |
- Goodacre, Dana, et al.
(author)
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Water adsorption on vanadium oxide thin films in ambient relative humidity
- 2020
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In: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 152:4
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Journal article (peer-reviewed)abstract
- In this work, ambient pressure X-ray photoelectron spectroscopy (APXPS) is used to study the initial stages of water adsorption on vanadium oxide surfaces. V 2p, O 1s, C 1s, and valence band XPS spectra were collected as a function of relative humidity in a series of isotherm and isobar experiments. Experiments were carried out on two VO2 thin films on TiO2 (100) substrates, prepared with different surface cleaning procedures. Hydroxyl and molecular water surface species were identified, with up to 0.5 ML hydroxide present at the minimum relative humidity, and a consistent molecular water adsorption onset occurring around 0.01% relative humidity. The work function was found to increase with increasing relative humidity, suggesting that surface water and hydroxyl species are oriented with the hydrogen atoms directed away from the surface. Changes in the valence band were also observed as a function of relative humidity. The results were similar to those observed in APXPS experiments on other transition metal oxide surfaces, suggesting that H2O-OH and H2O-H2O surface complex formation plays an important role in the oxide wetting process and water dissociation. Compared to polycrystalline vanadium metal, these vanadium oxide films generate less hydroxide and appear to be more favorable for molecular water adsorption.
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| 29. |
- Hahn, Ulrike, et al.
(author)
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Causal Argument
- 2017
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In: Oxford Handbook of Causal Reasoning. - : Oxford University Press. - 9780199399550
-
Book chapter (peer-reviewed)abstract
- This chapter outlines the range of argument forms involving causation that can be found in everyday discourse. It also surveys empirical work concerned with the generation and evaluation of such arguments. This survey makes clear that there is presently no unified body of research concerned with causal argument. It highlights the benefits of a unified treatment both for those interested in causal cognition and those interested in argumentation, and identifies the key challenges that must be met for a full understanding of causal argumentation.
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| 30. |
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| 31. |
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| 32. |
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| 33. |
- Karslloǧlu, Osman, et al.
(author)
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Prospects for the expansion of standing wave ambient pressure photoemission spectroscopy to reactions at elevated temperatures
- 2022
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In: Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films. - : American Vacuum Society. - 0734-2101 .- 1520-8559. ; 40:1
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Journal article (peer-reviewed)abstract
- Standing wave ambient pressure photoemission spectroscopy (SWAPPS) is a promising method to investigate chemical and potential gradients across solid-vapor and solid-liquid interfaces under close-to-realistic environmental conditions, far away from high vacuum. Until now, these investigations have been performed only near room temperature, but for a wide range of interfacial processes, chief among them being heterogeneous catalysis, measurements at elevated temperatures are required. One concern in these investigations is the temperature stability of the multilayer mirrors, which generate the standing wave field. At elevated temperatures, degradation of the multilayer mirror due to, for example, interdiffusion between the adjacent layers, decreases the modulation of the standing wave field, thus rendering SWAPPS experiments much harder to perform. Here, we show that multilayer mirrors consisting of alternate B4C and W layers are stable at temperatures exceeding 600 °C and are, thus, promising candidates for future studies of surface and subsurface species in heterogeneous catalytic reactions using SWAPPS.
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| 34. |
- Kaya, Sarp, et al.
(author)
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Highly Compressed Two-Dimensional Form of Water at Ambient Conditions
- 2013
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In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 3
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Journal article (peer-reviewed)abstract
- The structure of thin-film water on a BaF2(111) surface under ambient conditions was studied using x-ray absorption spectroscopy from ambient to supercooled temperatures at relative humidity up to 95%. No hexagonal ice-like structure was observed in spite of the expected templating effect of the lattice-matched (111) surface. The oxygen K-edge x-ray absorption spectrum of liquid thin-film water on BaF2 exhibits, at all temperatures, a strong resemblance to that of high-density phases for which the observed spectroscopic features correlate linearly with the density. Surprisingly, the highly compressed, high-density thin-film liquid water is found to be stable from ambient (300 K) to supercooled (259 K) temperatures, although a lower-density liquid would be expected at supercooled conditions. Molecular dynamics simulations indicate that the first layer water on BaF2(111) is indeed in a unique local structure that resembles high-density water, with a strongly collapsed second coordination shell.
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| 35. |
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| 36. |
- Miller, D. J., et al.
(author)
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Oxidation of Pt(111) under Near-Ambient Conditions
- 2011
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 107:19, s. 195502-
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Journal article (peer-reviewed)abstract
- The oxidation of Pt(111) at near-ambient O(2) pressures has been followed in situ using x-ray photoelectron spectroscopy (XPS) and ex situ using x-ray absorption spectroscopy (XAS). Polarization-dependent XAS signatures at the O K edge reveal significant temperature-and pressure-dependent changes of the Pt-O interaction. Oxide growth commences via a PtO-like surface oxide that coexists with chemisorbed oxygen, while an ultrathin alpha-PtO(2) trilayer is identified as the precursor to bulk oxidation. These results have important implications for understanding the chemical state of Pt in catalysis.
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| 37. |
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| 39. |
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| 41. |
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| 42. |
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| 43. |
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| 44. |
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| 45. |
- Yamamoto, S., et al.
(author)
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In situ x-ray photoelectron spectroscopy studies of water on metals and oxides at ambient conditions
- 2008
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In: Journal of Physics. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 20:18, s. 184025-
-
Research review (peer-reviewed)abstract
- X-ray photoelectron spectroscopy (XPS) is a powerful tool for surface and interface analysis, providing the elemental composition of surfaces and the local chemical environment of adsorbed species. Conventional XPS experiments have been limited to ultrahigh vacuum (UHV) conditions due to a short mean free path of electrons in a gas phase. The recent advances in instrumentation coupled with third-generation synchrotron radiation sources enables in situ XPS measurements at pressures above 5 Torr. In this paper, we describe the basic design of the ambient pressure XPS setup that combines differential pumping with an electrostatic focusing. We present examples of the application of in situ XPS to studies of water adsorption on the surface of metals and oxides including Cu(110), Cu(111), TiO2(110) under environmental conditions of water vapor pressure. On all these surfaces we observe a general trend where hydroxyl groups form first, followed by molecular water adsorption. The importance of surface OH groups and their hydrogen bonding to water molecules in water adsorption on surfaces is discussed in detail.
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| 46. |
- Yamamoto, S., et al.
(author)
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Water adsorption on α-Fe2O3 (0001) at near ambient conditions
- 2010
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In: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 114:5, s. 2256-2266
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Journal article (peer-reviewed)abstract
- We have investigated hydroxylation and water adsorption on α Fe 2O3(0001) at water vapor pressures up to 2 Torr and temperatures ranging from 277 to 647 K (relative humidity (RH)
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| 47. |
- Zhang, C., et al.
(author)
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Measuring fundamental properties in operating solid oxide electrochemical cells by using in situ X-ray photoelectron spectroscopy
- 2010
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In: Nature Materials. - : Springer Science and Business Media LLC. - 1476-4660 .- 1476-1122. ; 9:11, s. 944-949
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Journal article (peer-reviewed)abstract
- Photoelectron spectroscopic measurements have the potential to provide detailed mechanistic insight by resolving chemical states, electrochemically active regions and local potentials or potential losses in operating solid oxide electrochemical cells (SOCs), such as fuel cells. However, high-vacuum requirements have limited X-ray photoelectron spectroscopy (XPS) analysis of electrochemical cells to ex situ investigations. Using a combination of ambient-pressure XPS and CeO2-x/YSZ/Pt single-chamber cells, we carry out in situ spectroscopy to probe oxidation states of all exposed surfaces in operational SOCs at 750 °C in 1 mbar reactant gases H2 and H 2O. Kinetic energy shifts of core-level photoelectron spectra provide a direct measure of the local surface potentials and a basis for calculating local overpotentials across exposed interfaces. The mixed ionic/electronic conducting CeO2-x electrodes undergo Ce3+/Ce4+ oxidation-reduction changes with applied bias. The simultaneous measurements of local surface Ce oxidation states and electric potentials reveal the active ceria regions during H2 electro-oxidation and H2O electrolysis. The active regions extend ∼150 μm from the current collectors and are not limited by the three-phase-boundary interfaces associated with other SOC materials. The persistence of the Ce3+/Ce 4+ shifts in the ∼150 μm active region suggests that the surface reaction kinetics and lateral electron transport on the thin ceria electrodes are co-limiting processes.
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