Karen Appel

European XFEL · HED

The insulator–metal transition in liquid hydrogen is an important phenomenon to understand the interiors of gas giants, such as Jupiter and Saturn, as well as the physical and chemical behavior of materials at high pressures and temperatures. Here, the path toward an experimental approach is detailed based on spectrally resolved x-ray scattering, t...

A von Hámos spectrometer has been implemented in the vacuum interaction chamber 1 of the High Energy Density instrument at the European X-ray Free-Electron Laser facility. This setup is dedicated, but not necessarily limited, to X-ray spectroscopy measurements of samples exposed to static compression using a diamond anvil cell. Si and Ge analyser c...

Shown is a daughter crystal of K2[ZnCl4] in a fluid inclusion in pegmatite quartz from the Ehrenfriedersdorf tin deposit with high Rb, Cs, and Br concentrations.

The determination of the spin state of iron-bearing compounds at high pressure and temperature is crucial for our understanding of chemical and physical properties of the deep Earth. Studies on the relationship between the coordination of iron and its electronic spin structure in iron-bearing oxides, silicates, carbonates, iron alloys, and other mi...

We present recent results from an experiment carried out at the European X-ray free electron laser [1]. We harness the unique capabilities of the instrument to create solid density plasmas with tailored non-thermal electron distributions. By heating solids at photon energies above the k-edge, we create non-thermal photoelectrons that relax via coll...

In this study we present results of the dynamic compression of α-cristobalite up to a pressure of 106 GPa with the use of the dynamic diamond anvil cell. X-ray diffraction images were recorded at different ramp compression and decompression rates to investigate in situ the high-pressure phase transitions of α-cristobalite. Our results suggest that...

The European XFEL delivers up to 27000 intense (>10 ¹² photons) pulses per second, of ultrashort (≤50 fs) and transversely coherent X-ray radiation, at a maximum repetition rate of 4.5 MHz. Its unique X-ray beam parameters enable groundbreaking experiments in matter at extreme conditions at the High Energy Density (HED) scientific instrument. The p...

We present a proof-of-principle study demonstrating x-ray Raman Spectroscopy (XRS) from carbon samples at ambient conditions in conjunction with other common diagnostics to study warm dense matter, performed at the high energy density scientific instrument of the European x-ray Free Electron Laser (European XFEL). We obtain sufficient spectral reso...

The high-precision X-ray diffraction setup for work with diamond anvil cells (DACs) in interaction chamber 2 (IC2) of the High Energy Density instrument of the European X-ray Free-Electron Laser is described. This includes beamline optics, sample positioning and detector systems located in the multipurpose vacuum chamber. Concepts for pump–probe X-...

The ultrafast synthesis of ε-Fe3N1+x in a diamond-anvil cell (DAC) from Fe and N2 under pressure was observed using serial exposures of an X-ray free electron laser (XFEL). When the sample at 5 GPa was irradiated by a pulse train separated by 443 ns, the estimated sample temperature at the delay time was above 1400 K, confirmed by in situ transform...

We introduce a setup to measure high-resolution inelastic x-ray scattering at the High Energy Density scientific instrument at the European X-Ray Free-Electron Laser (XFEL). The setup uses the Si (533) reflection in a channel-cut monochromator and three spherical diced analyzer crystals in near-backscattering geometry to reach a high spectral resol...

The response of forsterite, Mg₂SiO₄, under dynamic compression is of fundamental importance for understanding its phase transformations and high‐pressure behavior. Here, we have carried out an in situ X‐ray diffraction study of laser‐shocked polycrystalline and single‐crystal forsterite (a‐, b‐, and c‐orientations) from 19 to 122 GPa using the Matt...

For the High-Energy-Density (HED) beamline at the SASE2 undulator of the European XFEL, a hard X-ray split-and-delay unit (SDU) has been built enabling time-resolved pump/probe experiments with photon energies between 5 keV and 24 keV. The optical layout of the SDU is based on geometrical wavefront splitting and multilayer Bragg mirrors. Maximum de...

Magnesite is observed to be chemically stable at high pressure (>80 GPa) (Binck et al., 2020). However, to constrain its stability in the lower mantle, we have to investigate its interaction with co-existing lower mantle phases. Previous experimental studies on MgCO3+SiO2 imply that at <35 GPa magnesite is stable at mantle geotherm conditions (Lita...

The von Hámos spectrometer setup at the HED instrument of the European XFEL is described in detail. The spectrometer is designed to be operated primarily between 5 and 15 keV to complement the operating photon energy range of the HED instrument. Four Highly Annealed Pyrolitic Graphite (HAPG) crystals are characterised with thicknesses of 40 μm or 1...

In situ x-ray diffraction and wave-profile measurements were carried out on polycrystalline boron carbide under laser- induced shock compression at 51 GPa at the Matter in Extreme Conditions end-station of the Linac Coherent Light Source. The diffraction data indicate that boron carbide remains crystalline to this pressure and there is no evidence...

The high-pressure phase transition of strontianite (SrCO3) was investigated at ambient temperature by means of powder and single-crystal X-ray diffraction. The samples were compressed in a diamond anvil cell to a maximum pressure of 49 GPa. Structure refinements confirm the existence of SrCO3 in the low pressure aragonite-type phase Pmcn (62) up to...

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

We present a method to determine the bulk temperature of a single crystal diamond sample at an X-Ray free electron laser using inelastic X-ray scattering. The experiment was performed at the high energy density instrument at the European XFEL GmbH, Germany. The technique, based on inelastic X-ray scattering and the principle of detailed balance, wa...

SiO2 is one of the most fundamental constituents in planetary bodies, being an essential building block of major mineral phases in the crust and mantle of terrestrial planets (1–10 ME). Silica at depths greater than 300 km may be present in the form of the rutile-type, high pressure polymorph stishovite (P42/mnm) and its thermodynamic stability is...

The European XFEL is a hard X-ray free-electron laser (FEL) based on a high-electron-energy superconducting linear accelerator. The superconducting technology allows for the acceleration of many electron bunches within one radio-frequency pulse of the accelerating voltage and, in turn, for the generation of a large number of hard X-ray pulses. We r...

In the laboratory study of extreme conditions of temperature and density, the exposure of matter to high intensity radiation sources has been of central importance. Here, we interrogate the performance of multi-layered targets in experiments involving high intensity, hard x-ray irradiation, motivated by the advent of extremely high brightness hard...

Beam conditioning CRL transfocator optics implemented at the Materials Imaging and Dynamics (MID) instrument of the European XFEL are described. Two CRL transfocator units are equipped with beryllium parabolic refractive lenses of large radii of curvature to provide collimated or focused x-ray beam in the 5-25 keV photon energy range. Optical schem...

The behavior of silicon carbide (SiC) under shock compression is of interest due to its applications as a high-strength ceramic and for general understanding of shock-induced polymorphism. Here we use the Matter in Extreme Conditions beamline of the Linac Coherent Light Source to carry out a series of time-resolved pump-probe x-ray diffraction meas...

Abstract In this paper, we show that supercritical fluids have a greater significance in the generation of pegmatites, and for ore-forming processes related to granites than is usually assumed. We show that the supercritical melt or fluid is a silicate phase in which volatiles; principally H2O are completely miscible in all proportions at magmatic...

In the original publication, there are some missing data in Table 1 and incorrect data in Table 2.

In this paper, we show that supercritical fluids have a greater significance in the generation of pegmatites, and for ore-forming processes related to granites than is usually assumed. We show that the supercritical melt or fluid is a silicate phase in which volatiles; principally H2O are completely miscible in all proportions at magmatic temperatu...

We present measurements of the plasmon shift in shock-compressed matter as a function of momentum transfer beyond the Fermi wavevector using an X-ray Free Electron Laser. We eliminate the elastically scattered signal retaining only the inelastic plasmon signal. Our plasmon dispersion agrees with both the random phase approximation (RPA) and static...

We describe a setup for performing inelastic X-ray scattering and X-ray diffraction measurements at the Matter in Extreme Conditions (MEC) endstation of the Linac Coherent Light Source. This technique is capable of performing high-, meV-resolution measurements of dynamic ion features in both crystalline and non-crystalline materials. A four-bounce...

In the laboratory study of extreme conditions of pressure, temperature, and timescale, the irradiation of matter by high intensity sources has been of central importance. Here we investigate the performance of layered targets in experiments involving very high intensity hard x-ray irradiation, motivated by the advent of extremely high brightness x-...

We describe a setup for performing inelastic X-ray scattering measurements at the Matter in Extreme Conditions (MEC) endstation of the Linac Coherent Light Source (LCLS). This technique is capable of performing high-, meV-resolution measurements of dynamic ion features in both crystalline and non-crystalline materials. A four-bounce silicon (533) m...

We present an extreme ultraviolet (EUV) microscope using a Schwarzschild objective which is optimized for single-shot sub-micrometer imaging of laser-plasma targets. The microscope has been designed and constructed for imaging the scattering from an EUV-heated solid-density hydrogen jet. Imaging of a cryogenic hydrogen target was demonstrated using...

Simulations of experiments at modern light sources, such as optical laser laboratories, synchrotrons, and free electron lasers, become increasingly important for the successful preparation, execution, and analysis of these experiments investigating ever more complex physical systems, e.g. biomolecules, complex materials, and ultra–short lived state...

The combination of powerful optical lasers and an x-ray free-electron laser (XFEL) provides unique capabilities to study the transient behaviour of matter in extreme conditions. The high energy density science instrument (HED instrument) at the European XFEL will provide the experimental platform on which an unique x-ray source can be combined with...

Carbonates are key-phases in the chemistry and dynamics of our planet. They are present from marine environments down to the lower mantle. Carbonate inclusions in kimberlitic diamonds have been shown to carry significant amounts of Sr and REE (Brenker et al., 2005; 2007). Carbonate-related element transport processes to the deep regions of the Eart...

Large explosive volcanic eruptions inject gases, aerosols, and fine ashes into the stratosphere, potentially influencing climate and atmosphere composition on a global scale. Although the potential climate effect of chlorine (Cl) and bromine (Br) injections into the stratosphere is known, the global mass fluxes are poorly constrained. In this study...

Trace element measurements in PM10-2.5, PM2.5-1.0 and PM1.0-0.3 aerosol were performed with 2 h time resolution at kerbside, urban background and rural sites during the ClearfLo winter 2012 campaign in London. The environment-dependent variability of emissions was characterized using the Multilinear Engine implementation of the positive matrix fact...

Trace element measurements in PM10–2.5, PM2.5–1.0 and PM1.0–0.3 aerosol were performed with 2 h time resolution at kerbside, urban background and rural sites during the ClearfLo winter 2012 campaign in London. The environment-dependent variability of emissions was characterized using the Multilinear Engine implementation of the positive matrix fact...

The advent of the first free-electron X-ray lasers (XFELs), FLASH in 2004 and LCLS in 2009, may prove to be the most profound development since the invention of the laser and, equally, the synchrotron. Sharp improvements in a number of laser parameters, most notably intensity and pulse duration, support this expectation. This brings scientific drea...

Free-electron laser facilities enable new applications in the field of high-pressure research including geo- and planetary sciences. At the European X-ray Free Electron Laser (XFEL) in Hamburg, one of the six baseline instruments is dedicated to High Energy Density Science (HED).1 A 100 J optical laser with nanosecond pulse duration, high repetitio...

The High Energy Density Science (HED) instrument at the European X-ray Free-Electron Laser Facility in Hamburg, Germany, is dedicated to the investigation of a wide range of materials and systems at extreme conditions of pressure, temperature, ionization or electro-magnetic field. For sample excitation a variety of high energy drivers will be insta...

The High Energy Density Science (HED) instrument at the European X-ray Free- Electron Laser Facility in Hamburg, Germany, is dedicated to the investigation of a wide range of materials and systems at extreme conditions of pressure, temperature, ionization or electro-magnetic field. For sample excitation a variety of high energy drivers will be inst...

Free-electron laser facilities enable new applications in the field of high-pressure research including geo- and planetary sciences. At the European X-ray Free Electron Laser (XFEL) in Hamburg, one of the six baseline instruments is dedicated to High Energy Density Science (HED). A 100 J optical laser with nanosecond pulse duration, high repetition...

Ambient concentrations of trace elements with 2 h time resolution were measured in PM10–2.5, PM2.5–1.0 and PM1.0–0.3 size ranges at kerbside, urban background and rural sites in London during winter 2012. Samples were collected using rotating drum impactors (RDIs) and subsequently analysed with synchrotron radiation-induced X-ray fluorescence spect...

Free-electron lasers (FELs) produce extremely intense, coherent and ultrashort pulses of light. Due to these properties, FELs can be used to investigate electronic and structural properties of short lived systems at very high spatial and temporal resolution and thus open up completely new scientific applications. From 2017 onwards, the European X-r...

This study aims at evaluating the capabilities of synchrotron radiation micro X-ray fluorescence spectrometry (SR micro-XRF) for qualitative and semi-quantitative elemental mapping of the distribution of actinides in human tissues originating from individuals with documented occupational exposure. The investigated lymph node tissues were provided b...

Free-electron laser facilities enable new applications in the field of high-pressure research including planetary materials. The European x-ray Free Electron Laser (European XFEL) in Hamburg, Germany will start user operation in 2017 and will provide photon energies of up to 25 keV. The high-energy density science instrument (HED) is one of the six...

The High Energy Density Physics (HED) instrument at the European XFEL will provide an unique platform for experiments combining hard x-ray FEL radiation (3 - 24 keV range) and the capability to generate matter under extreme conditions of pressure, temperature or electric field using high energy optical lasers (100 TW Ti-Sapphire and 100 J/ns diode-...

Free-electron laser facilities provide new applications in the field of high-pressure research including planetary materials. The European X-ray Free Electron Laser (XFEL) in Hamburg will start user operation in 2017 and will provide photon energies of up to 25 keV. With a photon flux of about 10^12 photons/pulse, with a pulse duration of 2-100 fs...

Free-electron laser facilities enable new applications in the field of high-pressure research including planetary materials. The European X-ray Free Electron Laser (European XFEL) in Hamburg, Germany will start user operation in 2017 and will provide photon energies of up to 25 keV. The high-energy density science instrument (HED) at the European X...

The High Energy Density science instrument at the European XFEL (HED) will provide unique possibilities for the investigation of near solid density matter at states of extreme excitation. Intense, coherent, and ultrashort x-ray pulses can be applied to obtain structural and electronic properties of these short-living systems. Located on the SASE 2...

For the High Energy Density (HED) experiment [1] at the European XFEL [2] an x-ray split- and delay-unit (SDU) is built covering photon energies from 5 keV up to 20 keV [3]. This SDU will enable time-resolved x-ray pump / x-ray probe experiments [4,5] as well as sequential diffractive imaging [6] on a femtosecond to picosecond time scale. Further,...

Free-electron laser facilities provide new applications in the field of high-pressure Research including planetary materials. The European X-ray Free Electron Laser (XFEL) in Hamburg will start user operation in 2017 and will provide photon energies of up to 25 keV. With a photon flux of about 10^12 photons/pulse, with a pulse duration of 2–100 fs...

Our previous studies carried out on the pilocarpine model of seizures showed that highly resolved elemental analysis might be very helpful in the investigation of processes involved in the pathogenesis of epilepsy, such as excitotoxicity or mossy fiber sprouting. In this study, the changes in elemental composition that occurred in the hippocampal f...

This technical design report (TDR) of the High Energy Density Physics scientific instrument (HED instrument) at the European XFEL outlines the scientific and technological requirements for the various subsystems and describes the technical realization chosen to match these requirements. The scientific requirements have been extracted from a range o...

Free-electron laser facilities provide new applications in the field of high-pressure research including planetary materials. The European X-ray Free Electron Laser (XFEL) in Hamburg, Germany will start user operation in 2017 and will provide photon energies of up to 25 keV. With a photon flux of ca 1012 photons/pulse, a pulse duration of 2 - 100 f...