| 1. |
- Herbschleb, C. T., et al.
(författare)
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The ReactorSTM : Atomically resolved scanning tunneling microscopy under high-pressure, high-temperature catalytic reaction conditions
- 2014
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 85:8
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Tidskriftsartikel (refereegranskat)abstract
- To enable atomic-scale observations of model catalysts under conditions approaching those used by the chemical industry, we have developed a second generation, high-pressure, high-temperature scanning tunneling microscope (STM): the ReactorSTM. It consists of a compact STM scanner, of which the tip extends into a 0.5 ml reactor flow-cell, that is housed in a ultra-high vacuum (UHV) system. The STM can be operated from UHV to 6 bars and from room temperature up to 600 K. A gas mixing and analysis system optimized for fast response times allows us to directly correlate the surface structure observed by STM with reactivity measurements from a mass spectrometer. The in situ STM experiments can be combined with ex situ UHV sample preparation and analysis techniques, including ion bombardment, thin film deposition, low-energy electron diffraction and x-ray photoelectron spectroscopy. The performance of the instrument is demonstrated by atomically resolved images of Au(111) and atom-row resolution on Pt(110), both under high-pressure and high-temperature conditions.
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| 2. |
- Frenken, T., et al.
(författare)
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Integrating chytrid fungal parasites into plankton ecology: research gaps and needs
- 2017
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Ingår i: Environmental Microbiology. - : Wiley. - 1462-2912. ; 19:10, s. 3802-3822
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Forskningsöversikt (refereegranskat)abstract
- Chytridiomycota, often referred to as chytrids, can be virulent parasites with the potential to inflict mass mortalities on hosts, causing e.g. changes in phytoplankton size distributions and succession, and the delay or suppression of bloom events. Molecular environmental surveys have revealed an unexpectedly large diversity of chytrids across a wide range of aquatic ecosystems worldwide. As a result, scientific interest towards fungal parasites of phytoplankton has been gaining momentum in the past few years. Yet, we still know little about the ecology of chytrids, their life cycles, phylogeny, host specificity and range. Information on the contribution of chytrids to trophic interactions, as well as co-evolutionary feedbacks of fungal parasitism on host populations is also limited. This paper synthesizes ideas stressing the multifaceted biological relevance of phytoplankton chytridiomycosis, resulting from discussions among an international team of chytrid researchers. It presents our view on the most pressing research needs for promoting the integration of chytrid fungi into aquatic ecology.
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| 3. |
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| 4. |
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| 5. |
- Westerström, Rasmus, et al.
(författare)
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Structure and reactivity of a model catalyst alloy under realistic conditions
- 2008
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Ingår i: Journal of Physics: Condensed Matter. - : IOP Publishing. - 1361-648X .- 0953-8984. ; 20:18, s. 6-184018
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Tidskriftsartikel (refereegranskat)abstract
- Using a combined experimental and theoretical approach, we show that a thin RhO2 oxide film forms on a Pt25Rh75(100) surface at elevated oxygen pressures and temperatures prior to the bulk oxidation. By the use of in situ surface x-ray diffraction under realistic CO oxidation reaction conditions, we show that the onset of the growth of thin RhO2 oxide film coincides with an increase in CO2 production. During the reaction, the consumed oxide film is continuously re-grown by oxygen in the gas phase. Our theoretical results strongly suggest that the CO adsorbs on the metallic substrate but reacts with the O in the RhO2 oxide film at the border between the RhO2 oxide film and the metallic substrate. This scenario could explain the experimental observations of oxidation reactions on other late transition metal surfaces as well as on their corresponding nanoparticles under realistic conditions.
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| 6. |
- Gustafson, Johan, et al.
(författare)
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Catalytic Activity of the Rh Surface Oxide: CO Oxidation over Rh(111) under Realistic Conditions
- 2010
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Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 114:10, s. 4580-4583
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Tidskriftsartikel (refereegranskat)abstract
- Using a combination of surface X-ray diffraction and mass spectrometry at realistic pressures, the CO oxidation reactivity of a Rh(111) model catalyst has been studied in conjunction with the surface structure. The measurements show that it specific thin surface oxide is always present in the high activity regime of Rh-based CO oxidation.
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| 7. |
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| 8. |
- van Rijn, R., et al.
(författare)
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Surface structure and reactivity of Pd(100) during CO oxidation near ambient pressures
- 2011
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Ingår i: Physical Chemistry Chemical Physics. - : Royal Society of Chemistry (RSC). - 1463-9084 .- 1463-9076. ; 13:29, s. 13167-13171
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Tidskriftsartikel (refereegranskat)abstract
- The surface structure of Pd(100) during CO oxidation was measured using a combination of a flow reactor and in situ surface X-ray diffraction coupled to a large-area 2-dimensional detector. The surface structure was measured for P-O2/P-CO ratios between 0.6 and 10 at a fixed total gas pressure of 200 mbar and a fixed CO pressure of 10 +/- 1 mbar. In conjunction with the surface structure the reactivity of the surface was also determined. For all P-O2/P-CO ratios the surface was found to oxidize above a certain temperature. Three different types of oxides were observed: the (root 5 x root 5)R27 degrees surface oxide, an epitaxial layer of bulk-like PdO, and a non-epitaxial layer of bulk-like PdO. As soon as an oxide was present the reactivity of the surface was found to be mass transfer limited by the flux of CO molecules reaching the surface.
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