Search

Non-symmorphic materials have recently been predicted to exhibit many different exotic features in their electronic structures. These originate from forced band degeneracies caused by the non-symmorphic symmetry, which not only creates the possibility to realize Dirac semimetals, but also recently resulted in the prediction of novel quasiparticles beyond the usual Dirac, Weyl or Majorana fermions, which can only exist in the solid state. Experimental realization of non-symmorphic materials that have the Fermi level located at the degenerate point is difficult, however, due to the requirement of an odd band filling. In order to investigate the effect of forced band degeneracies on the transport behavior, a material that has such a degeneracy at or close to the Fermi level is desired. Here, we show with angular resolved photoemission experiments supported by density functional calculations, that ZrSiTe hosts several fourfold degenerate Dirac crossings at the X point, resulting from non-symmorphic symmetry. These crossings form a Dirac line node along XR, which is located almost directly at the Fermi level and shows almost no dispersion in energy. ZrSiTe is thus the first real material that allows for transport measurements investigating Dirac fermions that originate from non-symmorphic symmetry., 13 pages, 4 figures, accepted for publication in New Journal of Physics

The E3 residual stress neutron diffractometer operated at Helmholtz-Zentrum Berlin (HZB) is designed for studies in material science and engineering applications. Recent upgrade activities have made the instrument faster and more adaptable to different types of measurement. Thus, E3 has become more attractive to a broad user community, including industry, and increased substantially its scientific output.

V4 is a small-angle neutron scatting instrument with an accessible range of scattering vector 0.01 nm-1 < Q < 8.5 nm-1. Outstanding features of the instrument are the polarized neutron option and the list mode data acquisition, allowing for time-resolved measurements with µs time resolution.

RNA helicase Brr2 is implicated in multiple phases of pre-mRNA splicing and thus requires tight regulation. Brr2 can be auto-inhibited via a large N-terminal region folding back onto its helicase core and auto-activated by a catalytically inactive C-terminal helicase cassette. Furthermore, it can be regulated in trans by the Jab1 domain of the Prp8 protein, which can inhibit Brr2 by intermittently inserting a C-terminal tail in the enzyme's RNA-binding tunnel or activate the helicase after removal of this tail. Presently it is unclear, whether these regulatory mechanisms functionally interact and to which extent they are evolutionarily conserved. Here, we report crystal structures of Saccharomyces cerevisiae and Chaetomium thermophilum Brr2-Jab1 complexes, demonstrating that Jab1-based inhibition of Brr2 presumably takes effect in all eukaryotes but is implemented via organism-specific molecular contacts. Moreover, the structures show that Brr2 auto-inhibition can act in concert with Jab1-mediated inhibition, and suggest that the N-terminal region influences how the Jab1 C-terminal tail interacts at the RNA-binding tunnel. Systematic RNA binding and unwinding studies revealed that the N-terminal region and the Jab1 C-terminal tail specifically interfere with accommodation of double-stranded and single-stranded regions of an RNA substrate, respectively, mutually reinforcing each other. Additionally, such analyses show that regulation based on the N-terminal region requires the presence of the inactive C-terminal helicase cassette. Together, our results outline an intricate system of regulatory mechanisms, which control Brr2 activities during snRNP assembly and splicing.

A versatile UHV-polarimeter for the EUV XUV spectral range is described which incorporates two optical elements: a phase retarder and a reflection analyzer. Both optics are azimuthally rotatable around the incident synchrotron radiation beam and the incidence angle is freely selectable. This allows for a variety of reflectometry, polarimetry and ellipsometry applications on magnetic or non-magnetic samples and multilayer optical elements.

The liquid flexRIXS endstation is dedicated to resonant inelastic x-ray scattering experiments on liquid samples and gasses in the soft x-ray range. The liquids are injected into the chamber via a liquid jet system whereas gasses and also small amounts of liquids can be investigated using a liquid/gas flow cell. The MCP-based RIXS spectrometer allows for a resolving power of better than 1000.

The X-ray Pump-Probe (XPP) experimental station predominantly aims at investigating hard and soft matter under a broad range of ambient conditions using time-resolved X-ray diffraction.

At BESSY II a large acceptance angle, multipurpose infrared beamline is available, comprising several end stations suitable for material and life science investigations. The beamline provides highly brilliant infrared radiation over the energy range from about 20,000 down to 30 cm-1 and even lower when BESSY II is run in the so-called low-a mode.

V7 has widely been recognized as a versatile and flexible instrument for innovative neutron imaging and has made decisive contributions to the development of new methods by exploiting different contrast mechanisms for imaging. The reason for the success in method development is the flexibility of the facility which permits very fast change of the instrument’s configuration and allows for performing non-standard experiments. The ability for complementary experiments with the laboratory X-ray tomographic scanner (MicroCT Lab) offers the opportunity to study samples at different contrast levels and spatial resolution scales.

Nanoparticles with size in the range from 10 nm to 300 nm and from three different materials (Au 10 nm, Ag 20 nm, and PSL 30 nm, 100 nm and 300 nm) were used in this supplementary comparison. The selected nanoparticles meet the requirements of different measurement methods such as Atomic Force Microscopy (AFM), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Dynamic Light Scattering (DLS), and Differential Mobility Analyzer (DMA), Small Angle X-Ray Scattering and for forth. All 37 participating laboratories returned results, but not all laboratories were able to perform measurement of all 5 nanoparticles. In order to determine the degree of equivalence (DOE), two reference values were considered in this comparison: the method dependent reference value (MRV) and the global reference value (GRV). The MRVs were determined for different measurement methods according to the corresponding reported uncertainties and measurement values from the participants. Each measurement method owns its own MRV. Since the measurement data from DLS were very different from and inconsistent with the measurement data from the other methods, the MRV for DLS was used in the En number calculation for the measurement data reported from the DLS method. The GRV was determined from the MRVs and their uncertainties of all the measurement methods except DLS, and was applied in the En number calculations for the measurement data reported from AFM, EM, DMA and SAXS methods. The assumption that the particles are spherical was commonly made in the nanoparticle measurements. Non-sphericity of particles, if exists, could have different impacts on different measurement methods. It is also important to note that the methods used are measuring mean diameters of a population of particles, not just a single particle, and that the meaning of the mean diameter could differ for different methods. Probably if participants include a different specific contribution in the uncertainty in a harmonized way, taking the non-cancelled method-dependent "systematic" errors into account, it may be easier to compare the results. KEY WORDS FOR SEARCH Nanoparticles; Atomic Force Microscopy (AFM); Transmission Electron Microscopy (TEM); Scanning Electron Microscopy (SEM); Dynamic Light Scattering (DLS); and Differential Mobility Analyzer (DMA); Small Angle X-Ray Scattering Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCL, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

In various mineralizing marine organisms, calcite or aragonite crystals form through the initial deposition of amorphous calcium carbonate (ACC) phases with different hydration levels. Using X-ray PhotoEmission Electron spectroMicroscopy (X-PEEM), ACCs with varied spectroscopic signatures were previously identified. In particular, ACC type I and II were recognized in embryonic sea urchin spicules. ACC type I was assigned to hydrated ACC based on spectral similarity with synthetic hydrated ACC. However, the identity of ACC type II has never been unequivocally determined experimentally. In the present study we show that synthetic anhydrous ACC and ACC type II identified here in sea urchin spines, have similar Ca L2,3-edge spectra. Moreover, using X-PEEM chemical mapping, we revealed the presence of ACC-H2O and anhydrous ACC in growing stereom and septa regions of sea urchin spines, supporting their role as precursor phases in both structures. However, the distribution and the abundance of the two ACC phases differ substantially between the two growing structures, suggesting a variation in the crystal growth mechanism; in particular, ACC dehydration, in the two-step reaction ACC-H2O → ACC → calcite, presents different kinetics, which are proposed to be controlled biologically. Keywords: Sea urchin spine regeneration, Anhydrous amorphous calcium carbonate, Hydrated amorphous calcium carbonate, Ca L2,3-edge spectra, PhotoEmission Electron spectroMicroscopy

Energy-level alignment at organic-metal interfaces plays a crucial role for the performance of organic electronic devices. However, reliable models to predict energetics at strongly coupled interfaces are still lacking. We elucidate contact formation of 1,2,5,6,9,10-coronenehexone (COHON) to the (1 1 1)-surfaces of coinage metals by means of ultraviolet photoelectron spectroscopy, x-ray photoelectron spectroscopy, the x-ray standing wave technique, and density functional theory calculations. While for low COHON thicknesses, the work-functions of the systems vary considerably, for thicker organic films Fermi-level pinning leads to identical work functions of 5.2 eV for all COHON-covered metals irrespective of the pristine substrate work function and the interfacial interaction strength.

The short-time dynamics of amorphous beryllium oxide (a-BeO) has been investigated for electronic excitation/ionization by fast incident electrons, as well as by Ar 7+ , Ar 15+ , Xe 15+ , and Xe 31+ ions at velocities of 6–10% the speed of light. Site specific Auger-electron spectra induced by fast heavy ions are the central point of this investigation. Electron induced Auger spectra serve as a reference and electron-energy loss (EELS) spectroscopy as well as resonant inelastic X-ray scattering (RIXS) are invoked for quantitative understanding. For the heavy-ion case, we observe strong variations in the corresponding spectral distributions of Be–K and O–K Auger lines. These are related to local changes of the electron density, of the electron temperature and even of the electronic band structure of BeO on a femtosecond time scale after the passage of highly charged heavy ions.

Short-wavelength XUV beam splitters consisting of multilayer reflective and transmissive coatings on 3 × 3 mm and 10 × 10 mm SiN membranes have been developed and fully characterized., Amplitude-division beam splitters for XUV radiation sources have been developed and extensively characterized. Mo/Si multilayer coatings were deposited on 50 nm-thick SiN membranes. By changing the multilayer structure (periodicity, number of bilayers, etc.) the intensity of the reflected and transmitted beams were optimized for selected incident radiation parameters (wavelength, incident angle). The developed optical elements were characterized by means of XUV reflectometry and transmission measurements, atomic force microscopy and optical interferometry. Special attention was paid to the spatial homogeneity of the optical response and reflected beam wavefront distortions. Here the results of the characterization are presented and improvements required for advanced applications at XUV free-electron lasers are identified. A flatness as low as 4 nm r.m.s. on 3 × 3 mm beam splitters and 22 nm r.m.s. on 10 × 10 mm beam splitters has been obtained. The high-spatial-frequency surface roughness was about 0.7–1 nm r.m.s. The middle-spatial-frequency roughness was in the range 0.2–0.8 nm r.m.s. The reflection and transmission of the beam splitters were found to be very homogeneous, with a deviation of less than 2% across the full optical element.

C60 fullerene crystals may serve as important catalysts for interstellar organic chemistry. To explore this possibility, the electronic structures of free-standing powders of C60 and (C59N)2 azafullerenes are characterized using X-ray microscopy with near-edge X-ray adsorption fine structure (NEXAFS) spectroscopy, closely coupled with density functional theory (DFT) calculations. This is supported with X-ray photoelectron spectroscopy (XPS) measurements and associated core-level shift DFT calculations. We compare the oxygen 1s spectra from oxygen impurities in C60 and C59N, and calculate a range of possible oxidized and hydroxylated structures and associated formation barriers. These results allow us to propose a model for the oxygen present in these samples, notably the importance of water surface adsorption and possible ice formation. Water adsorption on C60 crystal surfaces may prove important for astrobiological studies of interstellar amino acid formation.

We report a kinetic small angle neutron scattering study of the skyrmion lattice (SL) in MnSi. Induced by an oscillatory tilting of the magnetic field direction, the elasticity and relaxation of the SL along the magnetic field direction have been measured with microsecond resolution. For the excitation frequency of 325 Hz the SL begins to track the tilting motion of the applied magnetic field under tilting angles exceeding $\alpha_c$ > 0.4{\deg}. Empirically the associated angular velocity of the tilting connects quantitatively with the critical charge carrier velocity of approx. 0.1mm/s under current driven spin transfer torques, for which the SL unpins. In addition, a pronounced temperature dependence of the skyrmion motion is attributed to the variation of the skyrmion stiffness. Taken together our study highlights the power of kinetic small angle neutron scattering as a new experimental tool to explore, in a rather general manner, the elasticity and impurity pinning of magnetic textures across a wide parameter space without parasitic signal interferences due to ohmic heating or Oersted magnetic fields.

The flexible end station “FEMTOSPEX Molecules and Surfaces”, which will enable time resolved photoemission studies in the future at HZB, is presented.

Synchrotron radiation micro-X-Ray Fluorescence (m-XRF), X-ray photoelectron (XPS) and X-ray Absorption Fine Structure (XAFS) spectroscopies are applied for the study of paleontological findings. More specifically the costal plate of a gigantic terrestrial turtle Titanochelon bacharidisi and a fossilized coprolite of the cave spotted hyena Crocuta crocuta spelaea are studied. Ca L2,3-edge NEXAFS and Ca 2p XPS are applied for the identification and quantification of apatite and Ca containing minerals. XRF mapping and XAFS are employed for the study of the spatial distribution and speciation of the minerals related to the deposition environment. Fil: Zougrou, I.M.. Aristotle University of Thessalonik; Grecia Fil: Katsikini, M.. Aristotle University of Thessalonik; Grecia Fil: Pinakidou, F.. Aristotle University of Thessalonik; Grecia Fil: Brzhezinskaya, M.. No especifíca; Fil: Papadopoulou, L.. Aristotle University of Thessalonik; Grecia Fil: Vlachos, Evangelos. Aristotle University of Thessalonik; Grecia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Tsoukala, E.. Aristotle University of Thessalonik; Grecia Fil: Paloura, E.C.. Aristotle University of Thessalonik; Grecia

Due to its low redox potential and high theoretical specific capacity, Li metal has drawn worldwide research attention because of its potential use in next-generation battery technologies such as Li-S and Li-O2. Unfortunately, uncontrollable growth of Li microstructures (LmSs, e.g., dendrites, fibers) during electrochemical Li stripping/plating has prevented their practical commercialization. Despite various strategies proposed to mitigate LmS nucleation and/or block its growth, a fundamental understanding of the underlying evolution mechanisms remains elusive. Herein, synchrotron in-line phase contrast X-ray tomography was employed to investigate the morphological evolution of electrochemically deposited/dissolved LmSs nondestructively. We present a 3D characterization of electrochemically stripped Li electrodes with regard to electrochemically plated LmSs. We clarify fundamentally the origin of the porous lithium interface growing into Li electrodes. Moreover, cleavage of the separator caused by growing LmS was experimentally observed and visualized in 3D. Our systematic investigation provides fundamental insights into LmS evolution and enables us to understand the evolution mechanisms in Li electrodes more profoundly.

We find in the case of W(110) previously overlooked anomalous surface states having their spin locked at right angle to their momentum using spin-resolved momentum microscopy. In addition to the well known Dirac-like surface state with Rashba spin texture near the "Equation missing"-point, we observe a tilted Dirac cone with circularly shaped cross section and a Dirac crossing at 0.28 × "Equation missing" "Equation missing" within the projected bulk band gap of tungsten. This state has eye-catching similarities to the spin-locked surface state of a topological insulator. The experiments are fortified by a one-step photoemission calculation in its density-matrix formulation.

The mechanism of C–H activation in selective oxidation reactions of short-chain alkane molecules over transition metal oxides is critically affected by the balance of acid–base and redox sites at the surface of the catalyst. Using the example of manganese tungstate we discuss how the relative abundance of these sites can be controlled via synthetic techniques. Phase-pure catalysts composed of the thermodynamic stable monoclinic MnWO4 phase have been prepared using hydrothermal synthesis. Variation of the initial pH value resulted in rod-shaped nano-crystalline MnWO4 catalysts composed of particles with varying aspect ratio. The synthesis products have been analysed using transmission electron microscopy, X-ray diffraction, infrared, and photoelectron spectroscopy. In situ Raman spectroscopy was used to investigate the dissolution–re-crystallization processes occurring under hydrothermal conditions. Ethanol oxidation was applied to probe the surface functionalities in terms of acid–base and redox properties. Changes in the aspect ratio of the primary catalyst particles are reflected in the product distribution induced by altering the fraction of acid–base and redox sites exposed at the surface of the catalysts in agreement with the proposed mechanism of particle growth by re-crystallization during ageing under hydrothermal conditions.

LiXEdrom is an experimental station dedicated to high resolution RIXS measurements on liquid samples. It is equipped with two VLS gratings and advanced photon detector (MCP/phosphorous screen/CCD), covering soft X-ray range of 200 – 1200 eV. The efficient differential pumping and cooling systems ensure successful executions of X-ray spectroscopy on liquid samples in vacuum. Liquid samples are introduced into the vacuum chamber by micro-jet or flow-cell techniques.

The cerebellar floccular and parafloccular lobes are housed in fossae of the periotic region of the skull of different vertebrates. Experimental evidence indicates that the lobes integrate visual and vestibular information and control the vestibulo-ocular reflex, vestibulo-collic reflex, smooth pursuit and gaze holding. Multiple paleoneuroanatomy studies have deduced the behaviour of fossil vertebrates by measuring the floccular fossae (FF). These studies assumed that there are correlations between FF volume and behaviour. However, these assumptions have not been fully tested. Here, we used micro-CT scans of extant mammals (47 species) and birds (59 species) to test six possible morphological-functional associations between FF volume and ecological/behavioural traits of extant animals. Behaviour and ecology do not explain FF volume variability in four out of six variables tested. Two variables with significant results require further empirical testing. Cerebellum plasticity may explain the lack of statistical evidence for the hypotheses tested. Therefore, variation in FF volume seems to be better explained by a combination of factors such as anatomical and phylogenetic evolutionary constraints, and further empirical testing is required.

Multifunctional composite nanoprobes consisting of iron oxide nanoparticles linked to silver and gold nanoparticles, Ag–Magnetite and Au–Magnetite, respectively, were introduced by endocytic uptake into cultured fibroblast cells. The cells containing the non-toxic nanoprobes were shown to be displaceable in an external magnetic field and can be manipulated in microfluidic channels. The distribution of the composite nanostructures that are contained in the endosomal system is discussed on the basis of surface-enhanced Raman scattering (SERS) mapping, quantitative laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) micromapping, and cryo soft X-ray tomography (cryo soft-XRT). Cryo soft-XRT of intact, vitrified cells reveals that the composite nanoprobes form intra-endosomal aggregates. The nanoprobes provide SERS signals from the biomolecular composition of their surface in the endosomal environment. The SERS data indicate the high stability of the nanoprobes and of their plasmonic properties in the harsh environment of endosomes and lysosomes. The spectra point at the molecular composition at the surface of the Ag–Magnetite and Au–Magnetite nanostructures that is very similar to that of other composite structures, but different from the composition of pure silver and gold SERS nanoprobes used for intracellular investigations. As shown by the LA-ICP-MS data, the uptake efficiency of the magnetite composites is approximately two to three times higher than that of the pure gold and silver nanoparticles.

NEXAFS-RIXS and home laboratory-based UV-Vis absorption spectroscopy are combined to examine the speciation and electronic structure of para- aminobenzoic acid (PABA) in aqueous solution as a function of pH. DFT and TD- DFT electronic structure calculations reproduce the experimental trends and provide a correlation between the experimental HOMO↔LUMO gap as well as the electronic transitions between molecular orbitals in the non-ionic, anionic and cationic forms of PABA.

We have investigated the influence of multiple scattering on the magnetic small-angle neutron scattering (SANS) from a Nd–Fe–B nanocrystalline magnet. We performed sample-thickness- and neutron-wavelength-dependent SANS measurements, and observed the scattering vector dependence of the multiple magnetic scattering. It is revealed that significant multiple scattering exists in the magnetic scattering rather than the nuclear scattering of Nd–Fe–B nanocrystalline magnet. It is considered that the mean free path of the neutrons for magnetic scattering is rather short in Nd–Fe–B magnets. We analysed the SANS data by the phenomenological magnetic correlation model considering the magnetic microstructures and obtained the microstructural parameters.

U49/2 PGM1 is one of HZB open-port VUV beamlines. Therefore and due to the fact that it delivers highest flux with very acceptable energy resolution it is the most heavily booked BESSY II beamline. Earlier work has largely focused on surface science and catalysis. After shut down of the former U41 PGM an increasing number of experiments on liquids and solutions are carried out.

Although the chamber named ALICE was designed for the analysis of magnetic hetero- and nanostructures via resonant magnetic x-ray scattering, the instrument is not limited to this technique. Static measurements involve the possibility to use scattering and spectroscopy synchrotron based techniques (photon-in photon-out, photon-in electron-out, and coherent scattering). Dynamic experiments require either laser or magnetic field pulses to excite the spin system followed by x-ray probe in the time domain from nano- to femtosecond delay times. In this temporal range, the demagnetization/remagnetization dynamics and magnetization precession in a number of magnetic materials (metals, alloys, and magnetic multilayers) can be probed in an element specific manner. The versatility of the instrument was tested by a series of pilot experiments, pointing out ALICE as one of the most demanded instruments at the Helmholtz-Zentrum in Berlin.

The coherent soft-x-ray scattering experiment CXS has been developed to study nano-structured magnetic and nonmagnetic thin film samples in transmission or reflection geometry. A nanometer precision movable sample stage in a 1 Tesla magnet vector field together with a movable CCD detector, variable in sample – CCD distance, allows both XMCD and XMLD experiments in transmission and reflection as well as imaging techniques such as Fourier transform holography and ptychography.

The CISSY end station combines thin film deposition (sputtering, molecular beam epitaxy ambient-pressure methods) with surface and bulk-sensitive analysis (photo emission, x-ray emission, x-ray absorption) in the same UHV system, allowing fast and contamination–free transfer between deposition and analysis. It is mainly used for the fabrication and characterization of thin film devices and their components like thin film photovoltaic cells, water-splitting devices and other functional thin film materials.

Integrating epitaxial and ferromagnetic Europium Oxide (EuO) directly on silicon is a perfect route to enrich silicon nanotechnology with spin filter functionality. To date, the inherent chemical reactivity between EuO and Si has prevented a heteroepitaxial integration without significant contaminations of the interface with Eu silicides and Si oxides. We present a solution to this long-standing problem by applying two complementary passivation techniques for the reactive EuO/Si interface: ($i$) an $in\:situ$ hydrogen-Si $(001)$ passivation and ($ii$) the application of oxygen-protective Eu monolayers --- without using any additional buffer layers. By careful chemical depth profiling of the oxide-semiconductor interface via hard x-ray photoemission spectroscopy, we show how to systematically minimize both Eu silicide and Si oxide formation to the sub-monolayer regime --- and how to ultimately interface-engineer chemically clean, heteroepitaxial and ferromagnetic EuO/Si $(001)$ in order to create a strong spin filter contact to silicon., 11 pages of scientific paper, 10 high-resolution color figures. Supplemental information on the thermodynamic problem available (PDF). High-resolution abstract graphic available (PNG). Original research (2016)

The μmRIXS confocal plane grating spectrometer offers high resolution resonant inelastic x-ray scattering (RIXS) spectroscopy in the soft x-ray range between 50 eV and 1000 eV. The small focus of its dedicated beamline allows for spectroscopical imaging at selected sample sites with a spatial resolution of 1 micrometer.

Beamline UE49-SGM is a dedicated high-flux soft x-ray beamline, spanning the energy range of 95 eV to 1400 eV. Its micrometer focus makes it ideally suitable for investigation of small or inhomogeneous samples both with spectroscopic methods and coherent scattering as well as imaging techniques with full polarization control.

Optical design and technical data of the high-resolution normal incidence monochromator (NIM) beamline U125-2 NIM are presented.

The At-Wavelength Metrology Facility at BESSY-II is dedicated to short-term characterization of novel UV, EUV and XUV optical elements, such as diffraction gratings, mirrors, multilayers and nano-optical devices like reflection zone plates. It consists of an Optics Beamline PM-1 and a Reflectometer in a clean-room hutch as a fixed end station. The bending magnet Beamline is a Plane Grating Monochromator beamline (c-PGM) equipped with an SX700 monochromator. The beamline is specially tailored for efficient high-order suppression and stray light reduction. The versatile 11-axes UHV-Reflectometer can house life-sized optical elements, which are fully adjustable and of which the reflection properties can be measured in the full incidence angular range as well as in the full azimuthal angular range to determine polarization properties.

The KMC-2 beamline is dedicated to provide X-ray radiation with high energy stability and resolution. The experimental setup is optimized towards offering a wide range of methods and sample environments. Two permanent endstations can be used in alternation. DIFFRACTION is a flexible multi-purpose diffractometer, based on a Huber six circle diffractometer in psi geometry. XANES provides the possibility for EXAFS, XANES and X-ray fluorescence measurements at-air.

The lithiation and delithiation mechanisms of multiple Sn particles in a customized flat radiography cell were investigated by in amp; 8197;situ synchrotron radiography. For the first time, four de lithiation phenomena in a Sn electrode battery system are highlighted 1 amp; 8197;the de lithiation behavior varies between different Sn particles, 2 amp; 8197;the time required to lithiate individual Sn particles is markedly different from the time needed to discharge the complete battery, 3 amp; 8197;electrochemical deactivation of originally electrochemically active particles is reported, and 4 amp; 8197;a change of electrochemical behavior of individual particles during cycling is found and explained by dynamic changes of de lithiation pathways amongst particles within the electrode. These unexpected findings fundamentaly expand the understanding of the underlying de lithiation mechanisms inside commercial lithium ion batteries LIBs and would open new design principles for high performance next generation LIBs

The Macromolecular Crystallography (MX) group at the Helmholtz-Zentrum Berlin (HZB) is operating three state-of-the-art synchrotron beamlines for MX at BESSY II in Berlin (Heinemann et al., 2003; Mueller et al., 2012, 2015). The radiation source for all three beamlines BL14.1-3 is a superconducting 7T-wavelength shifter. Currently, the three beam lines are the most productive stations for MX in Germany, with about 250 PDB depositions per year and over 1500 PDB depositions in total (Status 10/2015). BL14.1 and BL14.2 are energy tuneable in the range 5.5-15.5 keV, while beam line BL14.3 is a fixed-energy side station operated at 13.8 keV. The HZB-MX beamlines are in regular user operation providing close to 200 beam days per year and about 600 user shifts to approximately 100 research groups across Europe. Additional user facilities include office space adjacent to the beam lines, a sample preparation laboratory, a biology laboratory (safety level 1) and high-end computing resources.

The FemtoSpeX facility of the BESSY II storage ring is dedicated to ultrafast optical-pump & soft x-ray probe experiments. Experimental end-stations for experiments in transmission, reflection, and diffraction geometry are available.

Highly controlled Fe-catalyzed growth of monolayer hexagonal boron nitride (h-BN) films is demonstrated by the dissolution of nitrogen into the catalyst bulk via NH3 exposure prior to the actual growth step. This “pre-filling” of the catalyst bulk reservoir allows us to control and limit the uptake of B and N species during borazine exposure and thereby to control the incubation time and h-BN growth kinetics while also limiting the contribution of uncontrolled precipitation-driven h-BN growth during cooling. Using in situ X-ray diffraction and in situ X-ray photoelectron spectroscopy combined with systematic growth calibrations, we develop an understanding and framework for engineering the catalyst bulk reservoir to optimize the growth process, which is also relevant to other 2D materials and their heterostructures.

PM3 merges the developments of the former BESSY I SX700 III monochromator for elliptically polarized VUV radiation and of BESSY II collimated plane grating monochromators. This way it is possible to achieve circular polarization from a BESSY II dipole in the range 20 – 2000 eV with high photon flux, high energy resolution and high stability.

L-edge soft X-ray spectroscopy has been proven to be a powerful tool to unravel the peculiarities of electronic structure of transition metal compounds in solution. However, the X-ray absorption spectrum is often probed in the total or partial fluorescence yield modes, what leads to inherent distortions with respect to the true transmission spectrum. In the present work, we combine photon- and electron-yield experimental techniques with multi-reference first principles calculations. Exemplified for the prototypical FeCl2 aqueous solution we demonstrate that the partial yield arising from the Fe3s → 2p relaxation is a more reliable probe of the absorption spectrum than the Fe3d → 2p one. For the bonding-relevant 3d → 2p channel we further provide the basis for the joint analysis of resonant photoelectron and inelastic X-ray scattering spectra. Establishing the common energy reference allows to assign both spectra using the complementary information provided through electron-out and photon-out events.

Silicon Si is proposed to be one of the most promising anode materials for next generation lithium ion batteries, but unsatisfactory discharge capacity and inevitable performance deterioration prevent their commercialisation. In amp; 8197;situ synchrotron X ray tomography is applied to a Si composite electrode based battery in its pristine and first discharged state and the degradation of the electron and or ion conducting network, as well as degradation of Si particles, is quantitatively investigated. Thus, this study is complementary to previous X ray tomographic studies focusing on Si particles only. On the electrode level, the Si particles located in the central part of the electrode primarily experience crack formation; on the particle level, lithiation behaviour is heterogeneous and cavities are formed during electrode preparation and battery operation. The correlation between the electrochemical activities of Si particles and their individual contact with the conducting network is investigated and quantified Si particles will experience lithiation only under the condition that at least 40 amp; 8201; of their surface is electrically and ionically connected

The Kirkpatrick–Baez (KB) refocusing mirrors unit at the PG1 beamline at FLASH has been newly designed, developed and fully commissioned. The vertical focal size of the KB optics is measured to be 5.8 ± 1 µm FWHM and the horizontal 6 ± 2 µm FWHM; astigmatism has been minimized to below 1 mm between waist positions. Such a tight focus is essential for the VUV double Raman spectrometer as it serves as an entrance slit for the first monochromator and defines its resolution to a very large extent. The Raman spectrometer is a permanent end-station at the PG1 beamline, dedicated to inelastic soft X-ray scattering experiments., The Kirkpatrick–Baez (KB) refocusing mirror system installed at the PG1 branch of the plane-grating monochromator beamline at the soft X-ray/XUV free-electron laser in Hamburg (FLASH) is designed to provide tight aberration-free focusing down to 4 µm × 6 µm full width at half-maximum (FWHM) on the sample. Such a focal spot size is mandatory to achieve ultimate resolution and to guarantee best performance of the vacuum-ultraviolet (VUV) off-axis parabolic double-monochromator Raman spectrometer permanently installed at the PG1 beamline as an experimental end-station. The vertical beam size on the sample of the Raman spectrometer, which operates without entrance slit, defines and limits the energy resolution of the instrument which has an unprecedented design value of 2 meV for photon energies below 70 eV and about 15 meV for higher energies up to 200 eV. In order to reach the designed focal spot size of 4 µm FWHM (vertically) and to hold the highest spectrometer resolution, special fully motorized in-vacuum manipulators for the KB mirror holders have been developed and the optics have been aligned employing wavefront-sensing techniques as well as ablative imprints analysis. Aberrations like astigmatism were minimized. In this article the design and layout of the KB mirror manipulators, the alignment procedure as well as microfocus optimization results are presented.

Reduction in metal oxide thin films has been suggested as the key mechanism responsible for forming conductive phases within solid state memory devices, enabling their resistive switching capacity. The quantitative spatial identification of such conductive regions is a daunting task, particularly for metal oxides capable of exhibiting multiple phases as in the case of TiOx. Here, we spatially resolve and chemically characterize distinct TiOx phases in localized regions of a TiOx based memristive device by combining full field transmission X ray microscopy with soft X ray spectroscopic analysis that is performed on lamella samples. We particularly show that electrically pre switched devices in low resistive states comprise reduced disordered phases with O Ti ratios around 1.37 that aggregate in a 100 nm highly localized region electrically conducting the top and bottom electrodes of the devices. We have also identified crystalline rutile and orthorhombic like TiO2 phases in the region adjacent to the main reduced area, suggesting that the temperature increases locally up to 1000 K, validating the role of Joule heating in resistive switching. Contrary to previous studies, our approach enables to simultaneously investigate morphological and chemical changes in a quantitative manner without incurring difficulties imposed by interpretation of electron diffraction patterns acquired via conventional electron microscopy techniques

Powder neutron diffraction measurements of PrNi_{5}Sn performed in the temperature range 1.5-76 K indicate that the compound crystallizes in a hexagonal CeNi_{5}Sn-type crystal structure (space group P6_{3}/mmc). The a lattice parameter and the unit cell volume V increase while the c lattice parameter does not change with increasing temperature. No long range magnetic ordering was detected down to 1.5 K, in contradiction to bulk magnetometric results.

The UE49-PGMa beamline hosts a photoemission electron microscope (PEEM) dedicated to spectromicroscopy and element-selective magnetic imaging on the nanometer scale. The instrument is an Elmitec PEEM III equipped with energy filter and Helium cooled manipulator. Laser driven excitations can be studied using an attached Ti:Sa laser. A variety of customized sample holders is available for imaging in moderate magnetic / electric field, temperature control, or local laser excitations. With x-rays the instrument is capable of 30 nm spatial resolution.

The V1 Membrane Diffractometer is dedicated for biological samples or other samples with large unit cells (5 -10 nm in cell length). Its main application is the investigation of biological and synthetic membranes,. For these studies, dedicated sample environment is available, including the new BerILL humidity chamber with a continuous range in relative humidity (RH) from 10 % RH to 100 % RH.

The THz beamline at BESSY II employs high power broadband femto to picosecond long THz pulses for magneto optical THz and FIR studies. A newly designed set up exploits the unique properties of ultrashort THz pulses generated by laser energy modulation of electron bunches in the storage ring or alternatively from compressed electron bunches. Experiments from 0.15 to 5 THz 5 150 cm 1 may be conducted at a user station equipped with a fully evacuated high resolution FTIR spectrometer 0.0063 cm 1 , lHe cooled bolometer detectors, a THz TDS set up and different sample environments, including a superconducting high field magnet 11 T 11T with variable temperature insert 1.5 K 300 K , a sample cryostat and a THz attenuated total reflection chamber. Main applications are Frequency Domain Fourier transform THz Electron Paramagnetic Resonance FD FT THz EPR , THz FTIR spectroscopy and optical pump THz probe time domain spectroscopy TDS , with sub ps time resolution