Sakura Pascarelli

• Doctor of Philosophy
• Scientific Director at European X-Ray Free-Electron Laser

Results of the 2018 commissioning and experimental campaigns of the new High Power Laser Facility on the Energy-dispersive X-ray Absorption Spectroscopy (ED-XAS) beamline ID24 at the ESRF are presented. The front-end of the future laser, delivering 15 J in 10 ns, was interfaced to the beamline. Laser-driven dynamic com­pression experiments were per...

Energy dispersive X-ray spectrometers provide a method for the fast data acquisition of X-ray absorption spectra. The intensity of the spectral components of a polychromatic beam is detected simultaneously after being dispersed in space, and being transmitted by an experimental sample. The cryogenic detector system called XH deploys a germanium mic...

Synchrotrons and free electron lasers are unique facilities to probe the atomic structure and electronic properties of matter at extreme thermodynamical conditions. In this context, "Matter at extreme pressures and temperatures" was one of the science drivers for the construction of low emittance 4thgeneration synchrotron sources such as the Extrem...

Structure–activity relations in heterogeneous catalysis can be revealed through in situ and operando measurements of catalysts in their active state. While hard X-ray tomography is an ideal method for non-invasive, multimodal 3D structural characterization on the micron to nm scale, performing tomography under controlled gas and temperature conditi...

The discovery of superconductivity above 250 K at high pressure in LaH10 and the prediction of overcoming the room temperature threshold for superconductivity in YH10 urge for a better understanding of hydrogen interaction mechanisms with the heavy atom sublattice in metal hydrides under high pressure at the atomic scale. Here we use locally sensit...

X-ray-based analytics are routinely applied in many fields, including physics, chemistry, materials science, and engineering. The full potential of such techniques in the life sciences and medicine, however, has not yet been fully exploited. We highlight current and upcoming advances in this direction. We describe different X-ray-based methodologie...

Germanium micro-strip sensors were selected as the sensor technology to take data in energy dispersive X-ray spectroscopy experiments at the Extremely Brilliant Source (EBS) in Grenoble (FR). It is important for this experimental technique to use sensors with a large uniform area and a fine pitch. The former determines the range of energy detectabl...

Nitrogen oxide (NOx) emissions are a major source of pollution, demanding ever-improving performance from catalytic after-treatment systems. However, catalyst development is often hindered by limited understanding of the catalyst at work, exacerbated by widespread use of model catalysts rather than technical catalysts, and by global rather than spa...

Time-resolved x-ray absorption experiments have been performed on shocked tantalum. Using a single 100 ps synchrotron x-ray pulse, nanosecond-lived equilibrium states of shocked solid Ta have been measured by L3-edge absorption spectroscopy. The energy shift and intensity change of the white line were measured up to 130 GPa and 2000 K. The experime...

The atomic environments involved in the magnetostriction effect in CoFe$_2$O$_4$ and La$_{0.5}$Sr$_{0.5}$CoO$_3$ polycrystalline samples have been identified by differential extended x-ray absorption fine structure (DiffEXAFS) spectroscopy. We demonstrate that cobalt atoms at octahedral sites are responsible for their magnetostriction. The analysis...

DESY and European XFEL organized an international expert meeting in November 2019. It was aimed at identifying and assessing the potential risks of dual use in the fields of FEL science and technology and at devising a nuanced approach based on best practices to guide the international research community. Approaches were taken to consider the topic...

Pulsed laser ablation in liquids is a hierarchical multi-step process to produce pure inorganic nanoparticle colloids. Controlling this process is hampered by the partial understanding of individual steps and structure formation. In situ X-ray methods are employed to resolve macroscopic dynamics of nanosecond PLAL as well to analyse the distributio...

The European XFEL is the first hard X-ray high-repetition-rate free-electron laser facility. Sakura Pascarelli, Serguei Molodtsov and Thomas Tschentscher, scientific directors of the European XFEL, discuss the challenges that lie ahead before the European XFEL can reach its full potential and cater for an international and diverse community of user...

We report high-pressure x-ray diffraction, x-ray absorption spectroscopy, and electrical transport measurements on CuMO 2 (M = Cr, Mn) delafossitelike oxides in an attempt to study their structural and electronic evolution with pressure. Recent studies of the similar CuFeO 2 delafossite has revealed a pressure-induced breaking of the unusual high a...

Atomic scale defects generated using focused ion as well as laser beams can activate ferromagnetism in initially non-ferromagnetic B2 ordered alloy thin film templates. Such defects can be induced locally, confining the ferromagnetic objects within well-defined nanoscale regions. The characterization of these atomic scale defects is challenging, an...

Nano-polycrystalline diamonds (NPDs) have become fundamental tools for cutting-edge X-ray absorption spectroscopy (XAS) studies at high P/T conditions that opened up new research directions by overcoming previous limitations. Indeed, NPDs yield a continuous and weak X-ray background signal which enables the collection of high-quality XAS data of m...

Noble gases are important geochemical tracers allowing reconstructing global volatile cycles in Earth's reservoirs. To constrain these fundamental processes, precise data on their partitioning behavior at deep Earth conditions are needed. Such data are only available at moderate pressures up to 25 GPa due to experimental challenges. We have investi...

In this work, we use extended X-ray absorption fine structure (EXAFS) data collected using nano-polycrystalline diamond anvil cell to study the atomic arrangement in Zr-Cu metallic glass in high pressure (HP) conditions. To reveal the microscopic details of stress accommodation mechanism, we performed molecular dynamics (MD) simulations of the HP a...

Changes of the magnetic and crystal structure on the microscopic scale in 40 nm FeRh thin films have been applied to investigate the phenomena of a disorder induced ferromagnetism at room temperature initiated through light ion-irradiation with fluences up to 0.125 Ne$^+$/nm$^{-2}$. Magnetometry shows an increase of magnetic ordering at low tempera...

The compression of liquid nickel and cobalt has been investigated up to 102 and 83 GPa, respectively, by x-ray absorption spectroscopy at the Ni and Co K edges, using laser-heated diamond anvil cell. A shortening of about 8%–10% of the metal bond distances is observed in the pressure range considered and the experimental results are confirmed by th...

The atomic environments involved in the magnetostriction effect in CoFe2O4 and La0.5Sr0.5CoO3 polycrystalline samples have been identified by differential extended x-ray absorption fine structure (DiffEXAFS) spectroscopy. We demonstrate that cobalt atoms at octahedral sites are responsible for their magnetostriction. The analysis of DiffEXAFS data...

The unconventional transport and magnetic properties of perovskitelike lanthanum cobalt oxide LaCoO 3 have been studied for more than five decades. This highly correlated electron system exhibits a variety of peculiar properties that are desirable for environmentally friendly energy solutions, fuel cell technologies, novel diesel engines, and oxyfu...

A pressure-induced collapse of magnetic ordering in β−Li2IrO3 at Pm∼1.5–2 GPa has previously been interpreted as evidence for possible emergence of spin liquid states in this hyperhoneycomb iridate, raising prospects for experimental realizations of the Kitaev model. Based on structural data obtained at room temperature, this magnetic transition is...

A pressure-induced collapse of magnetic ordering in β−Li2IrO3 at Pm∼1.5–2 GPa has previously been interpreted as evidence for possible emergence of spin liquid states in this hyperhoneycomb iridate, raising prospects for experimental realizations of the Kitaev model. Based on structural data obtained at room temperature, this magnetic transition is...

We studied FeCO3 using Fe K-edge X-ray absorption near-edge structure (XANES) spectroscopy at pressures up to 54 GPa and temperatures above 2000 K. First-principles calculations of Fe at the K-edge in FeCO3 were performed to support the interpretation of the XANES spectra. The variation of iron absorption edge features with pressure and temperature...

The 5d transition metals have attracted specific interest for high-pressure studies due to their extraordinary stability and intriguing electronic properties. In particular, iridium metal has been proposed to exhibit a recently discovered pressure-induced electronic transition, the so-called core-level crossing transition at the lowest pressure amo...

A pressure-induced collapse of magnetic ordering in $\beta$-Li$_2$IrO$_3$ at $P_m\sim1.5- 2$ GPa has previously been interpreted as evidence for possible emergence of spin liquid states in this hyperhoneycomb iridate, raising prospects for experimental realizations of the Kitaev model. Based on structural data obtained at \emph{room temperature}, t...

A new cell for in situ combined X-ray absorption, diffuse reflectance IR Fourier transform and mass spectroscopies (XAS–DRIFTS–MS) is presented. The cell stands out among others for its achievements and flexibility. It is possible to perform XAS measurements in transmission or fluorescence modes, and the cell is compatible with external devices lik...

X-ray magnetic circular dichroism (XMCD) studies at the Er L2,3 edges of Er3Fe5O12 exhibit a change of the spectral shape as a function of temperature and magnetic field. Using singular value decomposition, this variation is understood as a linear combination of two components. The dominating component is associated with the Er magnetization, while...

Supporting Information S1

Plain Language Summary Iron oxides are important end‐members of the complex materials that constitute the Earth's interior. Among them, FeO and Fe2O3 have long been considered as the main end‐members of the ferrous (Fe²⁺) and ferric (Fe³⁺) states of iron, respectively. All geochemical models assume that high oxygen concentrations are systematically...

Time-resolved X-ray Absorption (XAS) and UV/Vis spectroscopies with millisecond resolution are used simultaneously to investigate oxidation reactions of organic substrates by non-heme iron activated species. In particular, the oxidation processes of arylsulfides and benzyl alcohols by a non-heme iron oxo-complex have been studied. We show for the f...

The combination of complementary techniques in the characterization of catalysts under working conditions is a very powerful tool for an accurate and in-depth comprehension of the system investigated. In particular, X-ray absorption spectroscopy (XAS) coupled with diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and mass spectro...

The pyrite mineral MnS2 was recently shown to undergo a giant pressure-induced volume collapse at ∼ 12 GPa, via a disordered intermediate phase. The high pressure arsenopyrite phase is stabilised by metal-metal bonding, a mechanism now shown to be ubiquitous for Mn²⁺ chalcogenides. Here we report a spectroscopic investigation of this transition up...

Knowledge on the temperature distribution in high pressure and temperature devices is important for the interpretation of data and can often not be obtained from experiments. Here, we report on the thermal characteristics of the most employed Paris–Edinburgh press assemblies for in-situ X-ray purposes using finite element calculations. The maximal...

Antidot materials, i.e., two-dimensional nanostructures with a periodic array of nanopores, are of great scientific interest due to their unique nanomagnetic properties and their potential application in storage devices. It is well known that physical properties of antidots are directly linked to the diameter of nanopores and their spacing, as well...

In this article we present a direct comparison between reflective (Schwarzschild mirrors) and refractive (achromatic doublets) optics commonly used in spectroradiometric temperature measurements in laser heated diamond anvil cells. Emission spectra are fitted with the Planck's law and are further analysed with the two-colour technique; theoretical...

Using a simple slow decomposition method of nitrate precursors, high-surface area platinum-doped ceria with a crystallite size of 9 nm can be prepared. The catalytic performance of the compound can be tuned by changing the reduction temperature under hydrogen (300 °C, 500 °C and 700 °C). The catalyst treated at 300 °C shows the best catalytic perfo...

Following the Q2XAFS Workshop and Satellite to IUCr Congress 2017 on ‘Data Acquisition, Treatment, Storage – quality assurance in XAFS spectroscopy’, a summary is given of the discussion on different aspects of a XAFS experiment that affect data quality. Some pertinent problems ranging from sources and minimization of noise to harmonic contaminatio...

Extended X-ray absorption fine structure (EXAFS) at the Cd K edge and diffraction patterns have been measured on CdTe as a function of pressure from 100 kPa (1 bar) to 5 GPa using a cell with nano-polycrystalline diamond anvils and an X-ray focussing scanning spectrometer. Three phases - zincblende (ZB), mixed cinnabar-ZB and rocksalt (RS) - are we...

When high pressure is applied to Ce-Al metallic glasses, their disordered atomic structure exhibits some unusual properties like polyamorphism or transformation into a crystalline phase. In this work, we probe the atomic arrangement of Ce55Al45 and Ce75Al25 glasses by X-ray absorption spectroscopy and X-ray diffraction in the pressure range of 0–30...

The deposition of large amounts of mixed-valence Fe minerals in iron formations during the Archean and Paleoproterozoic indicates that the Fe(II)aq (aqueous) content of coeval anoxic seawater was likely several hundred M, compared to ca. 1 to 20 nM of the modern oxygenated ocean. It has been suggested that oxygen production along shallow marine con...

Solid krypton (Kr) undergoes a pressure-induced martensitic phase transition from a face-centered cubic (fcc) to a hexagonal close-packed (hcp) structure. These two phases coexist in a very wide pressure domain inducing important modifications of the bulk properties of the resulting mixed phase system. Here, we report a detailed in situ x-ray diffr...

A double-sided laser heating setup for diamond anvil cells installed on the ID24 beamline of the ESRF is presented here. The setup geometry is specially adopted for the needs of energy-dispersive X-ray absorption spectroscopic (XAS) studies of materials under extreme pressure and temperature conditions. We illustrate the performance of the facility...

Before the Archean to Proterozoic Transition (APT) the tectonic regime was domi- nated by microplates oating on a low viscosity mantle. Such a regime restricted chemical exchange between the shallow and deeper mantle reservoirs. After the APT, a more global convection regime led to deep subduction of slabs. We propose that the improved vertical mix...

A high-power, nanosecond pulsed laser impacting the surface of a material can generate an ablation plasma that drives a shock wave into it; while in situ x-ray imaging can provide a timeresolved probe of the shock-induced material behaviour on macroscopic length scales. Here, we report on an investigation into laser-driven shock compression of a po...

High-pressure x-ray absorption spectroscopy was performed at the Ir $L_3$ and $L_2$ absorption edges of Sr$_3$Ir$_2$O$_7$. The branching ratio of white line intensities continuously decreases with pressure, reflecting a reduction in the angular part of the expectation value of the spin-orbit coupling operator, $\left\langle {\bf L} \cdot {\bf S} \r...

High-pressure x-ray absorption spectroscopy was performed at the Ir L3 and L2 absorption edges of Sr3Ir2O7. The branching ratio of white-line intensities continuously decreases with pressure, reflecting a reduction in the angular part of the expectation value of the spin-orbit coupling operator, 〈L·S〉. Up to the high-pressure structural transition...

Carbonate-rich silicate and carbonate melts play a crucial role in deep Earth magmatic processes and their melt structure is a key parameter, as it controls physical and transport properties. Carbon-rich melts can be strongly enriched in trace elements, but the structural incorporation mechanisms of these elements are difficult to study because suc...

X-ray spectroscopic techniques have proven to be particularly useful in elucidating the molecular and electronic structural information of chemically heterogeneous and complex micro- and nano-structured materials. However, spatially resolved chemical characterization at the micrometre scale remains a challenge. Here, we report the novel hyperspectr...

Precise knowledge of the melting temperatures of iron, nickel and their alloys at pressures of the deep Earth would allow us to better constrain the parameters used for the Earth's heat budget and dynamics. However, melting curves of transition metals at pressures approaching 100 GPa and above are still controversial. To address this issue, we repo...

La K-edge X-ray absorption spectroscopy has been used to elucidate the changes in the local electronic and lattice structure that occur in the A-site deficient double perovskite La 1/3NbO 3 up to 6 GPa. The pressure evolution of the oxygen dodecahedrum around the A-site has been examined. XANES (X-ray absorption near edge structure) data show modif...

This chapter presents an overview of energy dispersive X-ray absorption spectroscopy (EDXAS), as developed and used at synchrotron radiation sources. It mainly covers time resolved studies, with emphasis on technical aspects.

Fluid catalytic cracking refers to a chemical conversion process of industrial scale. This process, utilizing porous catalysts composed of clay and zeolite, converts heavy crude oil fractions into transportation fuel and petrochemical feedstocks. Among other factors iron-rich reactor and feedstream impurities cause these catalyst particles to perma...

Fluid catalytic cracking refers to a chemical conversion process of industrial scale. This process, utilizing porous catalysts composed of clay and zeolite, converts heavy crude oil fractions into transportation fuel and petrochemical feedstocks. Among other factors iron-rich reactor and feedstream impurities cause these catalyst particles to perma...

A combined diffraction and EXAFS study of LaCoO3 and La0.5Sr0.5Co0.75Nb0.25O3 powders — CORRIGENDUM - E. A. Efimova, V. V. Sikolenko, D. V. Karpinsky, I. O. Troyanchuk, S. Pascarelli, C. Ritter, M. Feygenson, S. I. Tiutiunnikov, V. Efimov

An innovative approach aimed at disclosing the mechanism of chemical reactions occurring in solution in the ms time-scale is presented. Time-resolved Energy Dispersive X-ray Absorption and UV/Vis spectroscopies with millisecond resolution are used simultaneously to directly follow the evolution of both the oxidation state and the local structure of...

Ultrasonic irradiation of molten gallium in organic liquids (decane, dodecane, etc.) results in dispersion of the gallium into nanometric spheres. These were examined by several analytical methods XRD, DSC, Raman and IR spectroscopy) as well as electron microscopy (SEM, TEM) and found to be composed of Ga and C. The DSC analysis indicates that the...

A combination of neutron diffraction, synchrotron X-ray diffraction, and high-resolution extended X-ray absorption fine structure measurements has been used to clarify the correlations between long- and local-range structural distortions across the spin-state transition in powders of LaCoO 3 and La 0.5 Sr 0.5 Co 0.75 Nb 0.25 O 3 . The analysis of t...

Combined X-ray Photoelectron (XPS) and Absorption Fine Spectroscopy (XAFS) investigations on 10wt%Pd-16wt%Sb 10%Pd-16%Sb/TiO2 catalyst allow new insight into the impact of the co-component Sb on the active Pd species which catalyzes the gas phase acetoxylation of toluene to benzyl acetate. Ex situ Pd3d XPS and Pd L-edge XANES studies indicate the p...

A number of laser facilities coming online all over the world promise the capability of high-power laser experiments with shot repetition rates between 1 and 10 Hz. Target availability and technical issues related to the interaction environment could become a bottleneck for the exploitation of such facilities. In this paper, we report on target nee...

We present a combined high pressure Ni K-edge x-ray absorption and Raman spectroscopic investigation of β-Ni(OH) 2 . Extended x-ray absorption fine structure analysis reveals a progressive shrinking of the Ni–O and Ni–Ni bond distances with pressure. As pressure is increased, Raman data show a continuous hardening of the phonon modes associated wi...

The conditions of the pressure-induced (Formula presented.) phase transformation in zirconium have been reported to be influenced by the sample purity, the pressurizing conditions, and the deformation rate. Here, we study this transformation using a dynamic diamond-anvil cell compression setup and ms-scale time-resolved X-ray absorption spectroscop...

The magnetic and structural properties of cobalt were investigated under high pressure (160 GPa) and low temperature (50 K), by synchrotron K-edge x-ray magnetic circular dichroism and x-ray diffraction. A quasihydrostatic equation of state was measured up to 160 GPa. We found that uniaxial stress plays a role in the hexagonal close packed-face cen...

We present in this paper recent advances in the high pressure domain provided by the introduction of time-resolved energy-dispersive XAS (EDXAS) techniques at synchrotrons. We highlight technical aspects and describe two modes of acquisition: the ‘movie’ mode, where the time resolution is given by the detector acquisition speed and the ‘pump-and-pr...

Platinum nanoparticles dispersed on nanosized ceria are active for CO oxidation at room temperature after hydrogen pretreatment. High angular annular dark field -scanning transmission electron microscopy (HAADF-STEM) analysis of the reduced catalyst shows spreading of the 1 nm sized platinum particles under the electron beam, characteristic for two...

The local structure and dynamics of α-iron have been investigated by extended x-ray absorption fine structure (EXAFS) spectroscopy and x-ray diffraction (XRD) in order to shed light on some thermal and magnetic anomalies observed in the last decades. The quantitative EXAFS analysis of the first two coordination shells reveals a peculiar local vibra...

The pressure evolution of the local structure of Fe2O3 hematite has been determined by extended x-ray absorption fine structure up to ∼79 GPa. Below the phase-transition pressure at ∼50 GPa, no increasing of FeO6 octahedra distortion is observed as pressure is applied. Above the phase transition, an abrupt decrease of the nearest-neighbor Fe-O dist...

Understanding Warm Dense Matter (WDM), the state of planetary interiors, is a new frontier in scientific research. There exists very little experimental data probing WDM states at the atomic level to test current models and those performed up to now are limited in quality. Here, we report a proof-of-principle experiment that makes microscopic inves...

The noble gases are the most inert atomic group, but their reactivity increases with pressure. Diamond-anvil-cell experiments and ab initio modelling have been used to investigate a possible direct reaction between xenon and oxygen at high pressures. We have synthesized two oxides below 100 GPa, Xe2O5 under oxygen-rich conditions, and Xe3O2 under o...

Co-Pd multilayers obtained by Pd capping of pre-deposited Co nanoparticles on amorphous alumina are systematically studied by means of high-resolution transmission electron microscopy, x-ray diffraction, extended x-ray absorption fine structure, SQUID-based magnetometry, and x-ray magnetic circular dichroism. The films are formed by CoPd alloyed na...

In-situ EXAFS combined with a Paris-Edinburgh press (PEP) is an outstanding tool to investigate the local environment of trace elements in melts at high pressure and temperature. A novel design of the pressure assembly ensures a highly stable experimental setup (reaching temperatures of up to 2000 K at 2.5 GPa) while permitting the necessary level...

A combined high-resolution Co K-edge extended x-ray absorption fine structure (EXAFS) and high-resolution X-ray powder diffraction (XRD) study has been performed to clarify the detail of anomalous behavior of temperature-dependent magnetic susceptibility curve on the LaCoO3 across the spin-state (~120 K) transition. According to XRD analysis, the D...

The local structure of IrTe2 has been studied by iridium L3-edge x-ray absorption spectroscopy (XAS) measurements as a function of pressure, performed at two temperatures (100 and 295 K) across the structural phase transition at ∼270 K. Extended x-ray absorption fine structure (EXAFS) and x-ray absorption near-edge structure (XANES) spectra show pr...

To explore the microscopic response of a metallic glass (MG) to an applied hydrostatic load we performed a high-pressure extended x-ray absorption fine structure (EXAFS) study of the Zr66.7Cu33.3 amorphous alloy. EXAFS fitting revealed that on compression, Zr-Zr pairs are strained preferentially. Strong Zr-Cu interactions contribute to the stiffnes...

Ba8Si39Ge7 and Ba8Si29Ge17 have been studied at high pressure using x-ray diffraction and x-ray absorption spectroscopy (XAS) at the Ge K edge. In Ba8Si39Ge7, a transition is observed similar to the one in Ba8Si46, apparently isostructural. However, the XAS data analysis shows that the transformation is related to the off-centering of the Ba atoms....

Catalysts using platinum pre-formed nanoparticles were prepared as a strategy to evaluate the impact of structural and electronic properties of ceria-alumina-supports in the water gas shift reaction, minimizing variations of the metallic phase among samples. Promoted cerium Pt/Al2O3 catalysts, with 12 or 20 wt% of CeO2, were prepared by adding ceri...

The pressure evolution of the local structure of Fe2O3 hematite has been determined for the first time by extended x-ray absorption fine structure up to 79 GPa. The comparison to the different high-pressure forms proposed in the literature suggests that the orthorhombic structure with space group Aba2 is the most probable. The crossover from Fe hig...

Nb K-edge x-ray absorption spectroscopy is utilized to investigate the changes in the local structure of the A-site deficient double perovskite La1/3NbO3 which undergoes a pressure induced irreversible amorphization. EXAFS results show that with increasing pressure up to 7.5 GPa, the average Nb-O bond distance decreases in agreement with the expect...

The European Synchrotron Radiation Facility has recently made available to the user community a facility totally dedicated to Time-resolved and Extreme-conditions X-ray Absorption Spectroscopy – TEXAS. Based on an upgrade of the former energy-dispersive XAS beamline ID24, it provides a unique experimental tool combining unprecedented brilliance (up...

Fe-bearing carbonates have been proposed as possible candidate host minerals for carbon inside the Earth's interior and hence their spectroscopic properties can provide constraints on the deep carbon cycle. Here we investigate high-pressure spin crossover in synthetic FeCO3 (siderite) using a combination of Mössbauer, Raman, and X-ray absorption ne...

Skiagite-rich garnet was synthesized as single crystals at 9.5 GPa and 1100 °C using a multi-anvil apparatus. The crystal structure [cubic, space group Ia3̄d, a = 11.7511(2) Å, V = 1622.69(5) Å3, Dcalc = 4.4931 g/cm3] was investigated using single-crystal synchrotron X-ray diffraction. Synchrotron Mössbauer source spectroscopy revealed that Fe2+ an...

The structural properties of 1-hexyl-3-methylimidazolium iodide ([C6mim]I)/water mixtures with molar ratios ranging from 1:1 to 1:200 have been investigated using molecular dynamics (MD) simulations with extended X-ray absorption fine structure (EXAFS) experimental data. The presence of a complex network of interactions among cations, anions, and w...

BM23 is the general-purpose EXAFS bending-magnet beamline at the ESRF, replacing the former BM29 beamline in the framework of the ESRF upgrade. Its mission is to serve the whole XAS user community by providing access to a basic service in addition to the many specialized instruments available at the ESRF. BM23 offers high signal-to-noise ratio EXAF...

Significance There is a long-standing controversy over the melting curve of Fe at high pressure as determined from static laser heated diamond anvil cell and dynamic compression studies. X-ray absorption spectroscopy measurements are used here as a criterion to detect melting under pressure. Confronted with a diversity of obtained melting curves, t...