A5079027906- X-ray Spectroscopy and Fluorescence Analysis
- Advanced X-ray Imaging Techniques
- Arsenic contamination and mitigation
- Radioactive element chemistry and processing
- Heavy metals in environment
- Iron oxide chemistry and applications
- Geological and Geochemical Analysis
- Geochemistry and Elemental Analysis
- Electron and X-Ray Spectroscopy Techniques
- Clay minerals and soil interactions
- Mine drainage and remediation techniques
- Particle Accelerators and Free-Electron Lasers
- Nuclear Physics and Applications
- X-ray Diffraction in Crystallography
- Coal and Its By-products
- Chromium effects and bioremediation
- Crystallography and Radiation Phenomena
- Chalcogenide Semiconductor Thin Films
- Environmental remediation with nanomaterials
- Quantum Dots Synthesis And Properties
- Advancements in Photolithography Techniques
- Mineralogy and Gemology Studies
- Semiconductor materials and interfaces
- Copper-based nanomaterials and applications
- Crystallization and Solubility Studies
Karlsruhe Institute of Technology
2016-2025
University of Nevada, Las Vegas
2021
University of Southern Denmark
2021
Deutsches Elektronen-Synchrotron DESY
2015-2016
Kerntechnische Entsorgung Karlsruhe (Germany)
2015
FZI Research Center for Information Technology
1995-2007
Karlsruhe University of Education
2002
ETH Zurich
1990-1991
We report on the discovery of mineral ikaite (CaCO 3 ·6H 2 O) in sea‐ice from Southern Ocean. The precipitation CaCO during freezing seawater has previously been predicted thermodynamic modelling, indirect measurements, and documented artificial sea ice laboratory experiments but not reported for natural sea‐ice. It is assumed that formation may be important a ice‐driven carbon pump ice‐covered oceanic waters. Without direct evidence ice, its role this other processes remained speculative. O...
The substitution of rare metals such as iridium and platinum in light-emitting materials is a key step to enable low-cost mass-production organic diodes (OLEDs). Here, it demonstrated that using solution-processed, fully bridged dinuclear Cu(I)-complex can yield very high efficiencies. An optimized device gives maximum external quantum efficiency 23 ± 1% (73 2 cd A−1).
We investigated the speciation and extractability of Tl in soil developed from mineralized carbonate rock. Total concentrations topsoil (0–20 cm) 100–1000 mg/kg are observed most affected area, subsoil up to 6000 horizons containing weathered ore fragments. Using synchrotron-based microfocused X-ray fluorescence spectrometry (μ-XRF) absorption spectroscopy (μ-XAS) at L3-edge, partly Tl(I)-substituted jarosite avicennite (Tl2O3) were identified as Tl-bearing secondary minerals formed by...
We report on integrated geomorphological, mineralogical, geochemical and biological investigations of the hydrothermal vent field located floor density-stratified acidic (pH ~ 5) crater Kolumbo shallow-submarine arc-volcano, near Santorini. features rare geodynamic setting at convergent boundaries, where arc-volcanism seafloor activity are occurring in thinned continental crust. Special focus is given to unique enrichments polymetallic spires Sb Tl (±Hg, As, Au, Ag, Zn) indicating a new...
CAT-ACT-the hard X-ray beamline for CATalysis and ACTinide/radionuclide research at the KIT synchrotron radiation facility ANKA-is dedicated to spectroscopy, including "flux hungry" photon-in/photon-out correlative techniques combines state-of-the-art optics with a unique infrastructure radionuclide catalysis research. Measurements can be performed photon energies varying between 3.4 keV 55 keV, thus encompassing actinide M- L-edge or potassium K-edge up K-edges of lanthanide series such as...
A detailed characterization of the impact a RbF post-deposition treatment (RbF-PDT) on chemical structure wide-gap Cu(In, Ga)Se2 thin-film solar cell absorber surface with high Ga/(Ga + In) (GGI) ratio 0.9 is presented. Using synchrotron- and lab-based x-ray photoelectron spectroscopy, as well x-ray-excited Auger electron we observe distinct differences to RbF-PDT surfaces common GGI ∼0.3. In particular, reduces sodium oxide content at surface, while copper concentration not affected. We...
The mineralogical composition of mining wastes deposited in voluminous tailing impoundments around the world is key factor that controls retention and release pollutants. Here we report a detailed mineralogical, geochemical, microbiological investigation two near town Pezinok, Slovakia. primary objective this study was mineralogy formed impoundment after deposition tailings (so-called tertiary minerals). Tertiary minerals include oxyhydroxides Fe, Sb, As, Ca are present as grains rims on ore...
Hematite (α-Fe2O3) is one of the most common iron oxides and a sink for toxic metalloid arsenic. Arsenic can be immobilized by adsorption to hematite surface; however, incorporation As in was never seriously considered. In our study we present evidence that, besides adsorption, into crystals great relevance immobilization. With coupling nanoresolution techniques X-ray absorption spectroscopy presence (up 1.9 wt %) within could demonstrated. The incorporated As(5+) displays short-range order...
Luminescent Cu(I) complexes are interesting candidates as dopants in organic light-emitting diodes (OLEDs). However, open questions remain regarding the stability of such solution and therefore their suitability for processing. Since emission behavior emitters often drastically differs between bulk thin film samples, it cannot be excluded that changes partial decomposition or formation alternative emitting compounds upon processing responsible. In this study, we present three particularly...
Abstract Up to now, no consensus exists about the electronic nature of phosphorus (P) as donor for SiO 2 -embedded silicon nanocrystals (SiNCs). Here, we report on hybrid density functional theory (h-DFT) calculations P in SiNC/SiO system matching our experimental findings. Relevant configurations within SiNCs, at SiNC surfaces, sub-oxide interface shell and matrix were evaluated. Atom probe tomography (APT) its statistical evaluation provide detailed spatial distributions. For first time,...
The development of iridium-free, yet efficient emitters with thermally activated delayed fluorescence (TADF) was an important step towards mass production organic light-emitting diodes (OLEDs). Progress is currently impeded by the low solubility and chemical stability materials. Herein, we present a CuI -based TADF emitter that sufficiently chemically stable under ambient conditions can be processed printing techniques. drastically enhanced (to 100 g L-1 ) in relevant solvents. integrity...
Up to 1 billion people are affected by low intakes of the essential nutrient selenium (Se) due concentrations in crops. Biofortification this micronutrient plants is an attractive way increasing dietary Se levels. We investigated a promising method biofortification rice seedlings, as primary staple for 3 people, but naturally contains concentrations. studied hydroponic uptake 0–2500 ppb Se, potential phyto-toxicological effects and speciation along shoots roots function added species, other...
Abstract Hackmanites, a variety of sodalite with the general formula Na 8 Al 6 Si O 24 (Cl,S) 2 , are family nature‐based smart materials having ability for reversible photochromism upon UV or X‐ray exposure. Being nontoxic, cheap, and durable, hackmanite would be an optimal material visual detection presence X‐rays in simple portable systems. However, its X‐ray‐induced coloring abilities so far known only qualitatively. In this work, combination experimental computational methods is used to...
Arsenic (As) is a toxic element, and elevated levels of geogenic As in drinking water pose threat to the health several hundred million people worldwide. In this study, we used microfluidics combination with optical microscopy X-ray spectroscopy investigate zerovalent iron (ZVI) corrosion, secondary (Fe) phase formation, retention processes at pore scale ZVI-based treatment filters. Two 250 μm thick microchannels filled single ZVI quartz grain layers were operated intermittently (12 h...
Abstract Long‐term transformations of sulfur from atmospheric deposition in ombrotrophic peatlands have rarely been studied, although the potential impact on carbon mineralization and particularly methane formation is acknowledged. To elucidate long‐term fate peat, we therefore applied K‐edge X‐ray absorption near‐edge structure (XANES) spectroscopy to investigate with either natural or anthropogenic deposition. A peatland central Europe (Germany, BBM) experienced high during Industrial...
Abstract The chemical and electronic structure of the CdS/(Ag,Cu)(In,Ga)Se 2 (CdS/ACIGSe) interface for thin‐film solar cells, involving an absorber with a bulk [Ag]/([Ag]+[Cu]) (AAC) ratio 0.06, state‐of‐the‐art RbF post‐deposition treatment (PDT), chemical‐bath deposited CdS buffer layer, is studied. To gain detailed depth‐resolved picture CdS/ACIGSe interface, synchrotron‐ laboratory‐based hard X‐ray, soft UV photoelectron spectroscopy, inverse photoemission X‐ray emission spectroscopy...
view Abstract Citations (59) References (22) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS 7Li(n, gamma ) 8Li---Trigger Reaction to a Primordial it r-Process? Wiescher, Michael ; Steininger, Ralph Kaeppeler, Franz The cross section of the Li-7(n,gamma)Li-8 reaction was studied in neutron energy range 25-420 keV investigate role this for production nuclei with A 12 or greater primordial nucleosynthesis. experimental results are compared theoretical model...
Al2O3 on Si is known to form an ultrathin interfacial SiO2 during deposition and subsequent annealing, which creates a negative fixed charge ( Qfix) that enables field-effect passivation low surface recombination velocities in solar cells. Various concepts were suggested explain the origin of this Qfix. In study, we investigate Al-O monolayers (MLs) from atomic layer (ALD) sandwiched between deliberately grown/deposited films. We show Al atoms have ultralow diffusion coefficient (∼4 × 10-18...
Lanthanides are widely assumed not to form covalent bonds due the localized nature of their 4f valence electrons. This work demonstrates that ionic bond Sm(II) with cyclononatetraenyl (η