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- Fondell, Mattis, et al.
(author)
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Phase control of iron oxides grown in nano-scale structures on FTO and Si(100) : Hematite, maghemite and magnetite
- 2015
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In: Vacuum. - : Elsevier BV. - 0042-207X .- 1879-2715. ; 117, s. 85-90
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Journal article (peer-reviewed)abstract
- We demonstrate that iron oxide in the form of hematite, suitable as absorption material in photo-electrochemical cells, can be produced by pulsed chemical vapour deposition. By choosing carbon monoxide or nitrogen as carrier gases in the process the phase and granularity of the grown material can be controlled. The choice of carrier gas affect the decomposition rate of iron pentacarbonyl used as iron precursor. The iron oxide phase is also dependent on the chosen substrate, here fluorine doped tin oxide and crystalline silicon have been used. Regardless of the substrate nitrogen yields hematite, whereas carbon monoxide gives, magnetite on Si and maghemite on fluorine doped tin oxide. A combination of Raman spectroscopy, X-ray diffraction, and hard X-ray photoelectron spectroscopy were used for characterization of the crystalline phase and chemical composition in the films. Scanning electron microscopy were used to visualise the deposited films' nano-structure.
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| 3. |
- Johansson, Fredrik, et al.
(author)
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Resonant Auger spectroscopy on solid xenon on gold, silver, and copper substrates
- 2023
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In: Physical Review A: covering atomic, molecular, and optical physics and quantum information. - : American Physical Society (APS). - 2469-9926 .- 2469-9934. ; 107:3
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Journal article (peer-reviewed)abstract
- An investigation of the radiationless decay of core excited Xe atoms in the region of Xe L3M4,5M4,5 Auger electron kinetic energies (using x-ray energies in the vicinity of the L3 threshold) is presented for Xe adsorbed on Cu, Ag, and Au. The intensity distribution of the decay channels is different compared with Xe in the gas phase. Charge transfer of the core excited electron occurs within tens of attoseconds in all systems for excitation energies approaching the ionization threshold of the condensed system, whereas charge transfer times are substrate-dependent for lower excitation energies. The determination of partial yields into the decay channels allows for the observation of a decay channel present in the Xe/Cu and Xe/Ag systems but not in the case of Xe/Au. Theoretical calculations allow us to interpret this difference as emanating from varying amounts of the ground state hybridization between Xe and the substrates, which impacts the energy of the Auger final states enabling identification of these states giving rise to system specific features in the experimental data.
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| 4. |
- Malehmir, Alireza, 1977-, et al.
(author)
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Seismic imaging of dyke swarms within the Sorgenfrei-Tornquist Zone (Sweden) and implications for thermal energy storage
- 2018
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In: Solid Earth. - : Copernicus GmbH. - 1869-9510 .- 1869-9529. ; 9:6, s. 1469-1485
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Journal article (peer-reviewed)abstract
- There is a great interest and demand for green-type energy storage in Sweden for both short-and longterm (hours, days, weeks and seasons) periods. While there are a number of approaches proposed (e.g., compressed air, geothermal and thermal), only a few have commercially been demonstrated through upscaling projects. Among these, the thermal energy storage (TES) that stores energy (excess heat or cold) in fluids is particularly interesting. The excess energy can be stored underground in excavated caverns and used for large district heating and cooling purposes as well as for balancing and regulating electrical energy in power grids. For an upscaling underground TES project within the Tornquist suture zone of Scania in the southwest of Sweden, three high-resolution seismic profiles, each approximately 1 km long, were acquired. Geologically, the site sits within the southern margin of the Romeleasen fault zone in the Sorgenfrei-Tornquist Zone (STZ), where dolerite dyke swarms of Carboniferous-Permian age are observed striking in the SE-NW direction for hundreds of kilometers both on land and in offshore seismic and magnetic data (from Scania to Midland Valley in the UK). These dykes, 10-50 m thick, in the nearby quarries (within both Precambrian gneiss and quartzite) express themselves mostly in a subvertical manner. They can therefore act as a good water/fluid barrier, which can be an important geological factor for any TES site. For the data acquisition, combined cabled and wireless recorders were used to provide continuity on both sides of a major road running in the middle of the study area. Bedrock depressions are clearly depicted in the tomograms, suggesting the possibility of zones of weaknesses, highly fractured and/or weathered, in the bedrock and confirmed in several places by follow-up boreholes. Several steeply dipping (60-65 degrees) reflections were imaged down to 400 m depth and interpreted to originate from dolerite dykes. This interpretation is based on their orientations, strong amplitudes, regular occurrences and correlation with downhole logging data. In addition, groundwater flow measurements within the unconsolidated sediments and in bedrock suggest steeply dipping structures are the dominant factor in directing water mainly along a SE-NW trend, which is consistent with the strike of the dyke swarm within the STZ. To provide further insight on the origin of the reflections, even the historical crustalscale offshore BABEL (Baltic and Bothnian Echoes from the Lithosphere) lines (A-AA-AB) were revisited. Clear multiphase faults and signs of intrusions or melt source in the lower crust are observed, as well as a Moho step across the Tornquist zone. Overall, we favor that the reflections are of dolerite origin and their dip component (i.e., not subvertical) may imply a Precambrian basement (and dykes) tilting, block rotation, towards the NE as a result of the Romeleasen reverse faulting. In terms of thermal storage, these dykes then may be encountered during the excavation of the site and can complicate underground water flow should they be used as a fluid barrier in case of leakage.
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| 5. |
- Martorell, José Antonio Gordillo, et al.
(author)
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The Infinite Learning Chain. Flipped Professional Labs for Learning and Knowledge Co-Creation
- 2019
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In: Open Education Studies. - : Walter de Gruyter. - 2544-7831. ; 1, s. 151-176
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Journal article (peer-reviewed)abstract
- Nowadays universities and other classical research institutions are changing their role in knowledge creation. In general terms we can characterize this transition as the path from "Closed Science"to "Open Science"as a part of a deeper and structural phenomenon known as "knowledge democratization", where different stakeholders as students, makers and other tech and science enthusiasts are able to create knowledge learning from the researchers and cooperating with them. In this process, science engagement of these new actors is a key point to stimulate their creativity, get some important research skills learnt directly from the researchers and be able to apply these skills teaching others in a continuous "learning chain". In this article, we introduce some main features and preliminary results of an experiment called "The infinite learning chain"done in cooperation with Arduino, focused on sensing science and based in a real research project of Group of Atmospheric Science (GAS) called Luleå Environmental Monitoring Stations (LEMS). We debate some interesting questions related to the impact of the format in terms of science engagement, STEM skills acquisition and cooperative learning involvement. We used as "learning ecosystem"a professional Lab, the INSPIRE Lab a complete multidisciplinary facility for space and environmental research and exploration.
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