Local and Symmetry-Resolved Electronic Structure of Liquid Dimethyl Sulfoxide from Resonant Inelastic Soft X-ray Scattering.

Dimethyl sulfoxide (DMSO) is an important polar solvent that derives its unique properties from the lone pair and the strong polar bond at the sulfinyl functional group. To derive the local and symmetry-resolved electronic structure of liquid DMSO, we have used resonant inelastic soft X-ray scattering (RIXS) maps at the S L, C K, and O K edges. The experimental data are compared to calculations of spectra based on density functional theory, which allows a detailed analysis of the molecular orbitals throughout the molecule.

Valence-band hybridization in sulphides.

The hybridization state in solids often defines the critical chemical and physical properties of a compound. However, it is difficult to spectroscopically detect and evaluate hybridization beyond just general fingerprint signatures. Here, the valence-band hybridization of metal d-derived bands (short: "metal d bands") in selected metal sulphides is studied with a combined spectroscopic and theoretical approach to derive deeper insights into the fundamental nature of such compounds.

Chemical bonding effects in Sc compounds studied using X-ray absorption and X-ray photoelectron spectroscopies.

Advances on understanding the nature of the chemical bonding and electron correlation effects during the X-ray absorption process in ionic-covalent metal complexes has been achieved for most of the transition elements, except for scandium, due to the lack of a systematic series of spectroscopic reference spectra and the shortage of standard crystallographic data on scandium compounds. To close the gap, the chemical bonding effects in eight Sc compounds are studied using X-ray absorption spectroscopy (XAS) at Sc K and L absorption edges and X-ray photoelectron spectroscopy (XPS). Indeed, the fine structure of the XAS Sc K edge reflects the chemical sp-like bond formed between scandium and the ligand while the L edge and the pre-edge features of the K-edge provide a direct insight into the crystal field parameters at the Sc site in the coordination compound.

Rb Diffusion and Oxide Removal at the RbF-Treated GaO/Cu(In,Ga)Se Interface in Thin-Film Solar Cells.

We report on the chemical structure of Cu(In,Ga)Se (CIGSe) thin-film solar cell absorber surfaces and their interface with a sputter-deposited GaO buffer. The CIGSe samples were exposed to a RbF postdeposition treatment and an ammonia-based rinsing step, as used in corresponding thin-film solar cells. For a detailed chemical analysis of the impact of these treatments, we employed laboratory-based X-ray photoelectron spectroscopy, X-ray-excited Auger electron spectroscopy, and synchrotron-based hard X-ray photoelectron spectroscopy.

Characteristic of phosphorus rich compounds in the incinerated sewage sludge ashes: a case for sustainable waste management.

Growing concern over mineral resources supply forces us to search for alternative sources of Phosphorus. The possibility to recover phosphorus from incinerated sewage sludge ashes appears to be an important aspect in anthropogenic phosphorus cycle and sustainable economy. To make phosphorus recovery efficient it is important to learn the chemical and mineral composition of ash and phosphorus speciation.

Satellite-Dominated Sulfur L X-ray Emission of Alkaline Earth Metal Sulfides.

The sulfur L X-ray emission spectra of the alkaline earth metal sulfides BeS, MgS, CaS, SrS, and BaS are investigated and compared with spectra calculations based on density functional theory. Very distinct spectral shapes are found for the different compounds. With decreasing electronegativity of the cation, that is, increasing ionic bonding character, the upper valence band width and its relative spectral intensity decrease.

Spatiotemporal Mineral Phase Evolution and Arsenic Retention in Microfluidic Models of Zerovalent Iron-Based Water Treatment.

Arsenic (As) is a toxic element, and elevated levels of geogenic As in drinking water pose a threat to the health of several hundred million people worldwide. In this study, we used microfluidics in combination with optical microscopy and X-ray spectroscopy to investigate zerovalent iron (ZVI) corrosion, secondary iron (Fe) phase formation, and As retention processes at the pore scale in ZVI-based water treatment filters. Two 250 μm thick microchannels filled with single ZVI and quartz grain layers were operated intermittently (12 h flow/12 h no-flow) with synthetic groundwater (pH 7.

Coupling Methylammonium and Formamidinium Cations with Halide Anions: Hybrid Orbitals, Hydrogen Bonding, and the Role of Dynamics.

The electronic structures of four precursors for organic-inorganic hybrid perovskites, namely, methylammonium chloride and iodide, as well as formamidinium bromide and iodide, are investigated by X-ray emission (XE) spectroscopy at the carbon and nitrogen K-edges. The XE spectra are analyzed based on density functional theory calculations. We simulate the XE spectra at the Kohn-Sham level for ground-state geometries and carry out detailed analyses of the molecular orbitals and the electronic density of states to give a thorough understanding of the spectra.

Impact of -Butylammonium Bromide on the Chemical and Electronic Structure of Double-Cation Perovskite Thin Films.

2D/3D perovskite heterostructures have emerged as a promising material composition to reduce nonradiative recombination in perovskite-based LEDs and solar cells. Such heterostructures can be created by a surface treatment with large organic cations, for example, -butylammonium bromide (BABr). To understand the impact of the BABr surface treatment on the double-cation (CsFAPb(IBr)) (FA = formamidinium) perovskite thin film and further optimize the corresponding structures, an in-depth understanding of the chemical and electronic properties of the involved surfaces, interfaces, and bulk is required.

Sulfate Speciation Analysis Using Soft X-ray Emission Spectroscopy.

The chemical and electronic structures of 15 different sulfates are studied using S L soft X-ray emission spectroscopy (XES). Sulfur L XES spectra of sulfates are distinctively different from those of other sulfur compounds, which makes XES a powerful technique for sulfate detection. Furthermore, subtle but distinct differences between the spectra of sulfates with different cations are observed, which allow a further differentiation of the specific compound.

X-SPEC: a 70 eV to 15 keV undulator beamline for X-ray and electron spectroscopies.

X-SPEC is a high-flux spectroscopy beamline at the KIT (Karlsruhe Institute of Technology) Synchrotron for electron and X-ray spectroscopy featuring a wide photon energy range. The beamline is equipped with a permanent magnet undulator with two magnetic structures of different period lengths, a focusing variable-line-space plane-grating monochromator, a double-crystal monochromator and three Kirkpatrick-Baez mirror pairs. By selectively moving these elements in or out of the beam, X-SPEC is capable of covering an energy range from 70 eV up to 15 keV.

High Stability of Rh Oxide-Based Thermoresistive Catalytic Combustion Sensors Proven by X-ray Absorption Spectroscopy and X-ray Diffraction.

Thermoresistive catalytic combustion sensors based on noble metals are very stable stable and highly sensitive devices to monitor potentially explosive atmospheres. We studied and proved the high stability of rhodium oxide-based sensors under working conditions in different CH/air mixtures (up to 3.5 vol % methane) with the help of X-ray-based characterization techniques, DC resistance measurements, and IR thermography using a specially designed cell.

The potential wildfire effects on mercury remobilization from topsoils and biomass in a smelter-polluted semi-arid area.

Wildfires can be responsible for significant mercury (Hg) emissions especially in contaminated areas. Here, we investigated the Hg distribution in topsoils and vegetation samples and temperature-dependent Hg mobilization from biomass-rich topsoils collected near a copper (Cu) smelter in Tsumeb (semi-arid Namibia), where Hg-rich Cu concentrates are processed. The thermo-desorption (TD) experiments conducted on representative biomass-rich topsoils (3.

Effects of metal cation substitution on hexavalent chromium reduction by green rust.

Chromium contamination is a serious environmental issue in areas affected by leather tanning and metal plating, and green rust sulfate has been tested extensively as a potential material for in situ chemical reduction of hexavalent chromium in groundwater. Reported products and mechanisms for the reaction have varied, most likely because of green rust's layered structure, as reduction at outer and interlayer surfaces might produce different reaction products with variable stabilities. Based on studies of Cr(III) oxidation by biogenic Mn (IV) oxides, Cr mobility in oxic soils is controlled by the solubility of the Cr(III)-bearing phase.

The behaviour of irrigation induced Se in the groundwater-soil-plant system in Punjab, India.

Selenium is of special interest in different research fields due to its narrow range between beneficial and toxic effects. On a global scale, Se deficiency is more widespread. Biofortification measures have successfully been applied to specifically increase Se concentrations in food crops.

The role of soil components in synthetic mixtures during the adsorption and speciation changes of Cr(VI): Conjunction of the modeling approach with spectroscopic and isotopic investigations.

This study investigates redox transitions associated with the adsorption of Cr(VI) on commonly occurring soil components (silicates, oxides and humic acids) and their synthetic mixtures by coupling the mechanistic surface complexation modeling with spectroscopic and isotopic analyses. The mixtures of soil components were prepared to reflect the composition of the real anthroposol sample, determined by X-ray Powder Diffraction (XRD), total organic carbon (TOC) measurement and extraction methods. The effect of different initial Cr(VI) concentrations (2×10, 5×10, 10, 10, and 10M), background electrolyte (10, 10, and 10M KNO), pH values (3-9), and sorbate/sorbent ratios (2g/L - 20g/L) were investigated.

Synthesis and Structural Characterization of a Pure ZnAl(OH)(SO)·2.6HO Layered Double Hydroxide.

The phase purity of a series of ZnAl(OH)SO· nHO layered double hydroxides (ZnAl-LDH) obtained from a reaction of bayerite (Al(OH)) with an excess of zinc(II) sulfate under hydrothermal conditions was investigated as a function of the reaction temperature, the duration of the hydrothermal treatment, and the zinc(II) concentration. The product quality, i.e.

Hematite (α-FeO) - A potential Ce carrier in red mud.

Cerium is the most abundant rare earth element (REE) within the waste product of alumina production (red mud), but its speciation in this complex material is still barely understood. Previous studies showed evidence for a correlation between Ce and the main constituent of red mud, iron oxides, which led us to investigate the most abundant iron oxide in red mud, hematite, as possible carrier phase for Ce. Synthetic hematite can incorporate up to 1.

Towards Printed Organic Light-Emitting Devices: A Solution-Stable, Highly Soluble Cu -NHetPHOS.

The development of iridium-free, yet efficient emitters with thermally activated delayed fluorescence (TADF) was an important step towards mass production of organic light-emitting diodes (OLEDs). Progress is currently impeded by the low solubility and low chemical stability of the materials. Herein, we present a Cu -based TADF emitter that is sufficiently chemically stable under ambient conditions and can be processed by printing techniques.

Chromate adsorption on selected soil minerals: Surface complexation modeling coupled with spectroscopic investigation.

This study investigates the mechanisms of Cr(VI) adsorption on natural clay (illite and kaolinite) and synthetic (birnessite and ferrihydrite) minerals, including its speciation changes, and combining quantitative thermodynamically based mechanistic surface complexation models (SCMs) with spectroscopic measurements. Series of adsorption experiments have been performed at different pH values (3-10), ionic strengths (0.001-0.

Tracking Se Assimilation and Speciation through the Rice Plant - Nutrient Competition, Toxicity and Distribution.

Up to 1 billion people are affected by low intakes of the essential nutrient selenium (Se) due to low concentrations in crops. Biofortification of this micronutrient in plants is an attractive way of increasing dietary Se levels. We investigated a promising method of Se biofortification of rice seedlings, as rice is the primary staple for 3 billion people, but naturally contains low Se concentrations.

The role of nano-perovskite in the negligible thorium release in seawater from Greek bauxite residue (red mud).

We present new data about the chemical and structural characteristics of bauxite residue (BR) from Greek Al industry, using a combination of microscopic, analytical, and spectroscopic techniques. SEM-EDS indicated a homogeneous dominant "Al-Fe-Ca-Ti-Si-Na-Cr matrix", appearing at the microscale. The bulk chemical analyses showed considerable levels of Th (111 μg g(-1)), along with minor U (15 μg g(-1)), which are responsible for radioactivity (355 and 133 Bq kg(-1) for (232)Th and (238)U, respectively) with a total dose rate of 295 nGy h(-1).

Structural incorporation of As5+ into rhomboclase ((H5O2)Fe3+(SO4)2 · 2H2O) and (H3O)Fe(SO4)2.

Iron sulfates represent an essential sink for the toxic element arsenic in arid and semi-arid mining areas with high evaporation rates. Information about the structural incorporation of As(5+) in iron sulfates, however, remains scarce. Here we present evidence for the heterogeneous substitution of S(6+) by As(5+) in the crystal structure of rhomboclase ((H5O2)Fe(3+)(SO4)2 · 2H2O) and its dehydration product (H3O)Fe(SO4)2.