Polychromatic Synchrotron Radiation Research Articles

Restoring size of detonation nanodiamonds from small-angle x-ray scattering of polychromatic synchrotron radiation beam

Over the past two decades, LIH SB RAS and BINP SB RAS have jointly conducted experiments on time-resolved (TR) small-angle x-ray scattering (SAXS) with detonating high explosives. The purpose of these experiments is to restore the dynamics of carbon species condensation to diamond nanoparticles by analyzing series of SAXS patterns behind the detonation front measured in real time with fast detectors. This knowledge is crucial for the development of reliable detonation models. In this paper, we compare SAXS patterns of identical nanodiamond samples measured at the TR-SAXS extreme state of matter end-station (BINP SB RAS) in the static mode under realistic conditions simulating fast real-time measurements with polychromatic SR beam and traditional SAXS BioMUR beamline at the Kurchatov Synchrotron Radiation Source (NRC “Kurchatov Institute”) with monochromatic synchrotron radiation (SR) beam. These experiments confirm that the size of scattering inhomogeneities determined in dynamic experiments with single bunch exposure with polychromatic SR beam is correct.

Nanoprobing of MoS2 by Synchrotron Radiation When van der Waals Epitaxy Is Locally Invalid.

In this work, we demonstrated nano-scaled Laue diffractions by a focused polychromatic synchrotron radiation beam to discover what happens in MoS2 when van der Waals epitaxy is locally invalid. A stronger exciton recombination with a local charge depletion in the density of 1 × 1013 cm-2, extrapolated by Raman scattering and photoluminescence, occurs in grains, which exhibits a preferred orientation of 30° rotation with respect to the c-plane of a sapphire substrate. Else, the charge doping and trion recombination dominate instead. In addition to the breakthrough in extrapolating mesoscopic crystallographic characteristics, this work opens the feasibility to manipulate charge density by the selection of the substrate-induced disturbances without external treatment and doping. Practically, the 30° rotated orientation in bilayer MoS2 films is promoted on inclined facets in the patterned sapphire substrate, which exhibits a periodic array of charge depletion of about 1.65 × 1013 cm-2. The built-in manipulation of carrier concentrations could be a potential candidate to lateral and large-area electronics based on 2D materials.

Spectroscopic imaging with single acquisition ptychography and a hyperspectral detector

We present a new method of single acquisition spectroscopic imaging with high spatial resolution. The technique is based on the combination of polychromatic synchrotron radiation and ptychographic imaging with a recently developed energy discriminating detector. We demonstrate the feasibility with a Ni-Cu test sample recorded at I13-1 of the Diamond Light Source, UK. The two elements can be clearly distinguished and the Ni absorption edge is identified. The results prove the feasibility of obtaining high-resolution structural and chemical images within a single acquisition using a polychromatic X-ray beam. The capability of resolving the absorption edge applies to a wide range of research areas, such as magnetic domains imaging and element specific investigations in biological, materials, and earth sciences. The method utilises the full available radiation spectrum and is therefore well suited for broadband radiation sources.

Single-shot full strain tensor determination with microbeam X-ray Laue diffraction and a two-dimensional energy-dispersive detector.

The full strain and stress tensor determination in a triaxially stressed single crystal using X-ray diffraction requires a series of lattice spacing measurements at different crystal orientations. This can be achieved using a tunable X-ray source. This article reports on a novel experimental procedure for single-shot full strain tensor determination using polychromatic synchrotron radiation with an energy range from 5 to 23 keV. Microbeam X-ray Laue diffraction patterns were collected from a copper micro-bending beam along the central axis (centroid of the cross section). Taking advantage of a two-dimensional energy-dispersive X-ray detector (pnCCD), the position and energy of the collected Laue spots were measured for multiple positions on the sample, allowing the measurement of variations in the local microstructure. At the same time, both the deviatoric and hydrostatic components of the elastic strain and stress tensors were calculated.

On the possibilities of polychromatic synchrotron radiation microtomography for visualization of internal structures of Rhodnius prolixus

The recent years advancements in microtomography have increased the achievable resolution and contrast, making this relatively inexpensive and a widely available technology, potentially useful for studies of insect’s internal morphology. Phase Contrast X-Ray Synchrotron Microtomography (SR-PhC-µCT) is a non-destructive technique that allows the microanatomical investigations of Rhodnius prolixus, one of the most important insect vectors of Trypanosoma cruzi, the etiologic agent of Chagas’ disease. In Latin America, vector control is the most useful method to prevent Chagas’ disease, and a detailed knowledge of R. prolixus’ interior structures is crucial for a better understanding of their function and evolution. Traditionally, in both biological morphology and anatomy, the internal structures of whole organisms or parts of them are accessed by dissecting or histological serial sectioning; so studying the internal structures of R. prolixus’ head using SR-PhC-µCT is of great importance in researches on vector control. In this work, volume-rendered SR-PhC-µCT images of the heads of selected R. prolixus were obtained using the new set-up available at the SYRMEP beamline of ELETTRA (Trieste, Italy). In this new set-up, the outcoming beam from the ring is restrained before the monochromator and in a devoted end-station, absorption and phase contrast radiography and tomography set-up are available. The images obtained with polychromatic X-ray beam in phase contrast regimen and 2 µm resolution, showed details and organs of R. prolixus never seen before with SR-PhC-µCT.

Ultra-fast in-situ X-ray studies of evolving columnar dendrites in solidifying steel weld pools

High-brilliance polychromatic synchrotron radiation has been used to conduct in-situ studies of the solidification microstructure evolution during simulated welding. The welding simulations were realized by rapidly fusing ∼ 5 mm spot in Fe-Cr-Ni steel. During the solid- liquid-solid phase transformations, a section of the weld pool was placed in an incident 50-150 keV polychromatic synchrotron X-ray beam, in a near-horizontal position at a very low inclination angle. Multiple high-resolution 2D detectors with very high frame rates were utilized to capture time resolved X-ray diffraction data from suitably oriented solid dendrites evolving in the weld pool. Comprehensive analysis of the diffraction data revealed individual and overall dendritic growth characteristics and relevant melt and solid flow dynamics during weld pool solidification, which was completed within 1.5 s. Columnar dendrite tip velocities were estimated from the experimental data and during early stages of solidification were exceeded 4 mm/s. The most remarkable observation revealed through the time-resolved reciprocal space observations are correlated to significant tilting of columnar type dendrites at their root during solidification, presumably caused by convective currents in the weld pool. When the columnar dendrite tilting are transformed to respective metric linear tilting velocities at the dendrite tip; tilting velocities are found to be in the same order of magnitude as the columnar tip growth velocities, suggesting a highly transient nature of growth conditions.

Ultrafast Dynamical Study Using Time-resolved Laue Diffraction

Electron transfer reactions are fundamental processes in chemistry and also in biology [1-3]. Light harvesting complexes are functional centers in plants where sunlight is converted into chemical energy. In this, optical excitation in a chromophore unit leads to the transfer of electrons within the system. However, due to the complexity of the biological photo-reaction centre, recent spectroscopic efforts have concentrated on a smaller chemical model which share characteristic with their biological counter parts. A promising model is the so-called D-A (donor-acceptor) systems, which are chemically synthetic molecules with electron transfer capabilities. The electrical conductivity is a function of the optical state of the system. An optically switching diode is an interesting application of donor-acceptor molecules. We aimed to determine photo-induced structural changes in Pyrene-N,N-dimethylaniline (PyDMA). Static structures for many molecules are available at high resolution but the mechanism by which these molecules function and the structures of intermediate states often remain elusive. Knowledge of the geometry of molecular excited states at atomic resolution is crucial for a full understanding of photo-induced chemical processes. Time-resolved X-ray diffraction (TR-XRD) using polychromatic synchrotron radiation allows a detailed study of the time evolution of structural intermediates and short living states of chemical systems at wide range of time-scales, drawing a complete picture of the photo-induced charge transfer process. Investigation of photo-excitation processes in molecular single crystals, where the initial photo-excitation processes occur on extremely short time-scales (femto-/picosecond time domain) and have been in the focus of scientific investigations due to their possible applications, e.g. as optical switches.

Comparative Survival Analysis ofDeinococcus radioduransand the HaloarchaeaNatrialba magadiiandHaloferax volcaniiExposed to Vacuum Ultraviolet Irradiation

The haloarchaea Natrialba magadii and Haloferax volcanii, as well as the radiation-resistant bacterium Deinococcus radiodurans, were exposed to vacuum UV (VUV) radiation at the Brazilian Synchrotron Light Laboratory. Cell monolayers (containing 105 to 106 cells per sample) were prepared over polycarbonate filters and irradiated under high vacuum (10−5 Pa) with polychromatic synchrotron radiation. N. magadii was remarkably resistant to high vacuum with a survival fraction of (3.77±0.76)×10−2, which was larger than that of D. radiodurans (1.13±0.23)×10−2. The survival fraction of the haloarchaea H. volcanii, of (3.60±1.80)×10−4, was much smaller. Radiation resistance profiles were similar between the haloarchaea and D. radiodurans for fluences up to 150 J m−2. For fluences larger than 150 J m−2, there was a significant decrease in the survival of haloarchaea, and in particular H. volcanii did not survive. Survival for D. radiodurans was 1% after exposure to the higher VUV fluence (1350 J m−2), while N. magadii had a survival lower than 0.1%. Such survival fractions are discussed regarding the possibility of interplanetary transfer of viable microorganisms and the possible existence of microbial life in extraterrestrial salty environments such as the planet Mars and Jupiter's moon Europa. This is the first work to report survival of haloarchaea under simulated interplanetary conditions. Key Words: Vacuum ultraviolet—Synchrotron—Radiation resistance—Planetary protection—Panspermia. Astrobiology 11, 1034–1040.

On the possibilities of hard X-ray imaging with high spatio-temporal resolution using polychromatic synchrotron radiation

Time-resolved imaging with penetrating radiation has an outstanding scientific value but its realisation requires a high density of photons as well as corresponding fast X-ray image detection schemes. Bending magnets and insertion devices of third generation synchrotron light sources offer a polychromatic photon flux density which is high enough to perform hard X-ray imaging with a spatio-temporal resolution up to the μm-μs range. Existing indirect X-ray image detectors commonly used at synchrotron light sources can be adapted for fast image acquisition by employing CMOS-based digital high speed cameras already available on the market. Selected applications from life sciences and materials research underline the high potential of this high-speed hard X-ray microimaging approach.

Copper Sulfide Assisted Recrystallization of Cu-poor CuInS2 Observed in-situ by Polychromatic X-ray Diffraction

AbstractThe microstructural changes during heating of bi-layers of Cu-poor CuInS2 and CuS under different sulfur excess conditions were studied. This was done by means of energy dispersive X-ray diffraction of polychromatic synchrotron radiation in a vacuum setup where the sulfur pressure conditions can be controlled. Understood as the formation of a new microstructure, the recrystallization of the Cu-poor CuInS2 phase was characterized by a change in the reflection profile (from Cauchy-type to Gauss-type), the reduction of the breadth and a subsequent normalized-intensity increase of the 112 reflection. The Cauchy component of the breadth was used to monitor the recrystallization under different sulfur and heating rate conditions. The main results are: a) Cu availability for the consumption of the CuIn5S8 phase is a pre-requisite for recrystallization, b) in presence of the Cu2-xS phase, increased sulfur pressure enhances recrystallization.

Powder diffractometry on polychromatic synchrotron radiation (approach to a problem)

Abstract The method of the determination of interplanar spaces and relative intensities for polycrystalline samples from the X-ray patterns that have been taken in polychromatic radiation is offered. The method is based on the construction of a model X-ray pattern and minimization of the difference between it and the experimental curve. It is shown by model experiments for SrO 2 , Cu and Al that the method is proof against experimental errors and that errors of definition of parameters are of the same order as those for X-rays pattern obtained in monochromatic radiation. The influence of absorption edges of elements being a part of the sample on the X-ray pattern and the possibility of using them for improvement of experiment quality are discussed.

Zone-plate-array lithography using synchrotron radiation

We present our results in the design and development of a multiple-beam x-ray pattern generator based on an array of Fresnel zone plates (FZPs). Exposures have been carried out using a synchrotron source at SuperACO (France), a PC-controlled piezoelectric scanning stage, and an array of FZPs fabricated by high resolution electron-beam lithography and reactive-ion etching of a tungsten absorber. In particular, we have implemented an array of apertures using a self-aligned process in order to minimize background intensity coming from diffraction orders other than the positive first order. We show that even with polychromatic synchrotron radiation and relatively low resolution FZPs, patterns of various geometries could be successfully written in poly(methylmethacrylate) resist and submicrometer resolution was obtained after metal liftoff.

Ab initiostructure determination of low-molecular-weight compounds using synchrotron radiation Laue diffraction

The potential of using polychromatic synchrotron radiation for ab initio structure determination of low-molecular-weight compounds is investigated. Three different organic compounds were studied. For each of the structures the cell volume was determined with the aid of a Zr attenuator that was placed in the direct beam to obtain a sharp \lambda_{\rm min} edge. Space-group determination did not prove to be complicated; it was aided by deconvolution of the multiple spots. Two low-temperature data sets were collected, and it appeared that spot streaking owing to the inherent increase of mosaicity due to freezing was not too detrimental to the application of the Laue method. Although both the R_{\rm merge} values (around 12%) and the final R_1 values (around 10%) are higher than usually found in monochromatic experiments, all structures show reasonable geometry. Comparison of one of the structures with a reference structure obtained with monochromatic data shows an r.m.s. deviation between the 21 non-H-atom positions of 0.019 Å.

Calculation of the optimal specimen thickness for small-angle X-ray experiments with the use of polychromatic synchrotron radiation

An evaluation method of the optimal specimen thickness for small-angle X-ray experiments using polychromatic synchrotron radiation (SR) is put forward. Curves of the dependence of the optimal specimen thickness on various SR-spectra with a one-dimensional detector and Si(Li) SSD are calculated. The curves allow one to optimize an experiment by selecting either the optimal specimen thickness for an available SR-spectrum or the short-wave spectrum limit for a given specimen thickness (fibers, tissues, etc.). Besides increasing both precision and reproducibility of the X-ray experiments, the method gives the possibility either to increase the statistical precision within a given recording time of an X-ray pattern and/or to decrease the recording time with retention of the same statistical precision. It is shown that a deviation of 15–20% in the specimen thickness from the optimal thickness leads to a decrease in the scattering intensity of less than 2%.

Sub-20 nm x-ray nanolithography using conventional mask technologies on monochromatized synchrotron radiation

The optimal wavelength range for x-ray lithography is usually estimated between 0.8 and 1.4 nm. In this work, the use of a monochromator working at 1.1 nm on synchrotron radiation is reported. Replication results in this monochromatic mode are compared with results obtained for a polychromatic synchrotron radiation centered at 0.8 nm in terms of resolution and image contrast. Two conventional mask technologies are used for this study. The influence of the mask contrast is also studied. A nondestructive soft contact system was chosen to lower the gap below 1 μm. An ultimate resolution of 20 nm is shown in PMMA resist as well as 35 nm in PMMA/MAA (8.5%) resist for the monochromatic mode. The effect of photoelectrons created in the substrate is also investigated by replications on Si substrates coated with a Cr/Au bilayer. In addition, the daughtering of high resolution masks at 1.1 nm is successfully performed in the 20 nm range by Au electroplating.

放射光Ｘ線結晶学で今何ができるか？ 微少量・高精度・極限に迫る 極微小結晶・微小領域の構造解析

Structural studies on a sub-micrometer-sized crystal grain and on micrometer-sized area are introduced on the equipment and method of structure refinement based on the Laue intensities obtained with polychromatic synchrotron radiation. Some examples of analyses are also given.

Coherent grating x-ray diffraction (CGXD) and its applications (invited)

We show that an x-ray interference phenomenon, coherent grating x-ray diffraction (CGXD), can be used to study lateral nanostructure arrays on crystal surfaces and interfaces. Compared to Fraunhofer grating diffraction of visible light, x-ray grating diffraction contains information not only about geometric profiles of the surface but also about the internal crystalline structures and lattice strain distributions in the grating features. The grating diffraction pattern can also be measured in a white-beam Laue method using highly collimated polychromatic synchrotron radiation, which provides a parallel data collection scheme and may be useful in in situ studies on evolution of nanostructure arrays.

Energy dispersive x-ray diffraction of micro-crystals at ultrahigh pressures

Abstract Ultrahigh pressures and temperatures in diamond-anvil cells are achieved at the expense of reducing sample volume. The capability of x-ray diffraction with high spatial resolution is most fundamental for probing microscopic samples at the maximum P-T and for minimizing the effect of gradients. Polychromatic synchrotron radiation with energy dispersive x-ray diffraction is ideal for the development of new classes of structural microprobes. Primary x-ray beams down to 3 microns can be produced with microbeam slit systems and microfocusing optical devices. The microprobe can be routinely used for a variety of high-pressure experiments, including single-crystal x-ray diffraction above 50 GPa, polycrystal-line diffraction above 300 GPa, deviatoric strain measurements, and diffraction at simultaneous high pressure and temperature.

Development of a microarea diffraction system by polychromatic synchrotron radiation with the Laue method

Microarea diffraction equipment has been developed with a micropinhole and an imaging plate using the Laue method combined with polychromatic synchrotron radiation. The crystal structure of 8 μm diam area of olivine [(Mg,Fe)2SiO4] grain included in a thin section of meteorite was successfully refined based on the intensities of Laue spots.

Study of Periodic Surface Nanostructures Using Coherent Grating X-Ray Diffraction (Cgxd)

AbstractIt is shown that an x-ray interference phenomenon, Coherent Grating X-ray Diffraction (CGXD), can be used to study lateral nanostructure arrays on crystal surfaces and interfaces. Compared to Fraunhofer grating diffraction of visible light, x-ray grating diffraction contains information not only about geometric profiles of a surface, but also about the internal crystalline structures and lattice strain distributions in grating features. Grating diffraction patterns can also be measured in a white-beam Laue method using highly collimated polychromatic synchrotron radiation. This provides a way for parallel data collection and is useful in in-situ studies of structural evolution of nanostructure arrays.