scholarly journals Imaging local electric fields produced upon synchrotron X-ray exposure

2014 ◽  
Vol 112 (3) ◽  
pp. 696-701 ◽  
Author(s):  
Christopher M. Dettmar ◽  
Justin A. Newman ◽  
Scott J. Toth ◽  
Michael Becker ◽  
Robert F. Fischetti ◽  
...  
Keyword(s):  
Electric Fields ◽  
Second Harmonic ◽  
Soft Materials ◽  
Local Fields ◽  
X Rays ◽  
Electron Hole ◽  
X Ray ◽  
X Ray Absorption ◽  
Static Electric Fields ◽  
Cryogenic Conditions

Electron–hole separation following hard X-ray absorption during diffraction analysis of soft materials under cryogenic conditions produces substantial local electric fields visualizable by second harmonic generation (SHG) microscopy. Monte Carlo simulations of X-ray photoelectron trajectories suggest the formation of substantial local electric fields in the regions adjacent to those exposed to X-rays, indicating a possible electric-field–induced SHG (EFISH) mechanism for generating the observed signal. In studies of amorphous vitreous solvents, analysis of the SHG spatial profiles following X-ray microbeam exposure was consistent with an EFISH mechanism. Within protein crystals, exposure to 12-keV (1.033-Å) X-rays resulted in increased SHG in the region extending ∼3 μm beyond the borders of the X-ray beam. Moderate X-ray exposures typical of those used for crystal centering by raster scanning through an X-ray beam were sufficient to produce static electric fields easily detectable by SHG. The X-ray–induced SHG activity was observed with no measurable loss for longer than 2 wk while maintained under cryogenic conditions, but disappeared if annealed to room temperature for a few seconds. These results provide direct experimental observables capable of validating simulations of X-ray–induced damage within soft materials. In addition, X-ray–induced local fields may potentially impact diffraction resolution through localized piezoelectric distortions of the lattice.

SOFT X-RAY MICROSCOPY OF SOFT MATTER — HARD INFORMATION FROM TWO SOFTS

2002 ◽  
Vol 09 (01) ◽  
pp. 193-201 ◽  
Author(s):  
A. P. HITCHCOCK ◽  
C. MORIN ◽  
T. TYLISZCZAK ◽  
I. N. KOPRINAROV ◽  
H. IKEURA-SEKIGUCHI ◽  
...  
Keyword(s):  
Soft Matter ◽  
Phase Segregation ◽  
Soft Materials ◽  
Quantitative Information ◽  
Quantitative Chemical Analysis ◽  
X Rays ◽  
X Ray ◽  
Hard Information ◽  
Scanning Transmission ◽  
X Ray Absorption

Scanning transmission X-ray microscopy (STXM) and X-ray photoelectron emission microscopy (X-PEEM) provide quantitative chemical analysis at a spatial resolution well below 100 nm. Soft X-ray absorption or near edge X-ray absorption (NEXAFS) contrast provides sensitive differentiation of species which have similar elemental composition but are chemically distinct. Due to the ability of soft X-rays at wavelengths below the O K-edge to penetrate water, and on account of lower radiation damage, soft X-ray microscopy is an ideal tool for providing quantitative information about soft matter in the context of biological, polymer and environmental studies. Examples are given from recent studies of: phase segregation in polyurethanes and polymer blends, protein adsorption on polymers relating to biomaterial optimization, and metal mapping in biofilms. These examples show that it is indeed possible to get quantitative (hard) information by combining soft X-rays and soft materials.

Current Status of Solid-State X-Ray Systems

1985 ◽  
Vol 43 ◽  
pp. 158-161
Author(s):  
Martin Peckerar ◽  
Anastasios Tousimis
Keyword(s):  
Solid State ◽  
Electric Fields ◽  
Spectral Lines ◽  
Current Status ◽  
Mobile Charge ◽  
Electron Hole ◽  
X Ray ◽  
Sensing Systems ◽  
Transmission Electron ◽  
Electron Microscopes

Solid state x-ray sensing systems have been used for many years in conjunction with scanning and transmission electron microscopes. Such systems conveniently provide users with elemental area maps and quantitative chemical analyses of samples. Improvements on these tools are currently sought in the following areas: sensitivity at longer and shorter x-ray wavelengths and minimization of noise-broadening of spectral lines. In this paper, we review basic limitations and recent advances in each of these areas. Throughout the review, we emphasize the systems nature of the problem. That is. limitations exist not only in the sensor elements but also in the preamplifier/amplifier chain and in the interfaces between these components.Solid state x-ray sensors usually function by way of incident photons creating electron-hole pairs in semiconductor material. This radiation-produced mobile charge is swept into external circuitry by electric fields in the semiconductor bulk.

X-Ray absorption edge elemental imaging of B. thuringienis

1989 ◽  
Vol 47 ◽  
pp. 212-213
Author(s):  
R. L. Stears
Keyword(s):  
Absorption Edge ◽  
Elemental Distribution ◽  
X Rays ◽  
Differential Absorption ◽  
Synchrotron Source ◽  
High Brightness ◽  
X Ray ◽  
Elemental Imaging ◽  
Cellular Integrity ◽  
X Ray Absorption

Because of the nature of the bacterial endospore, little work has been done on analyzing their elemental distribution and composition in the intact, living, hydrated state. The majority of the qualitative analysis entailed intensive disruption and processing of the endospores, which effects their cellular integrity and composition.Absorption edge imaging permits elemental analysis of hydrated, unstained specimens at high resolution. By taking advantage of differential absorption of x-ray photons in regions of varying elemental composition, and using a high brightness, tuneable synchrotron source to obtain monochromatic x-rays, contact x-ray micrographs can be made of unfixed, intact endospores that reveal sites of elemental localization. This study presents new data demonstrating the application of x-ray absorption edge imaging to produce elemental information about nitrogen (N) and calcium (Ca) localization using Bacillus thuringiensis as the test specimen.

scholarly journals Al-driven peculiarities of local coordination and magnetic properties in single-phase Alx-CrFeCoNi high-entropy alloys

Nano Research ◽  
2021 ◽  
Author(s):  
Alevtina Smekhova ◽  
Alexei Kuzmin ◽  
Konrad Siemensmeyer ◽  
Chen Luo ◽  
Kai Chen ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Single Phase ◽  
Magnetic Circular Dichroism ◽  
Surface Region ◽  
Face Centered Cubic ◽  
X Rays ◽  
X Ray ◽  
High Entropy ◽  
X Ray Absorption ◽  
Absorption Edges

AbstractModern design of superior multi-functional alloys composed of several principal components requires in-depth studies of their local structure for developing desired macroscopic properties. Herein, peculiarities of atomic arrangements on the local scale and electronic states of constituent elements in the single-phase face-centered cubic (fcc)- and body-centered cubic (bcc)-structured high-entropy Alx-CrFeCoNi alloys (x = 0.3 and 3, respectively) are explored by element-specific X-ray absorption spectroscopy in hard and soft X-ray energy ranges. Simulations based on the reverse Monte Carlo approach allow to perform a simultaneous fit of extended X-ray absorption fine structure spectra recorded at K absorption edges of each 3d constituent and to reconstruct the local environment within the first coordination shells of absorbers with high precision. The revealed unimodal and bimodal distributions of all five elements are in agreement with structure-dependent magnetic properties of studied alloys probed by magnetometry. A degree of surface atoms oxidation uncovered by soft X-rays suggests different kinetics of oxide formation for each type of constituents and has to be taken into account. X-ray magnetic circular dichroism technique employed at L2.3 absorption edges of transition metals demonstrates reduced magnetic moments of 3d metal constituents in the sub-surface region of in situ cleaned fcc-structured Al0.3-CrFeCoNi compared to their bulk values. Extended to nanostructured versions of multicomponent alloys, such studies would bring new insights related to effects of high entropy mixing on low dimensions.

scholarly journals Synchrotron X-ray induced acoustic imaging

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Seongwook Choi ◽  
Eun-Yeong Park ◽  
Sinyoung Park ◽  
Jong Hyun Kim ◽  
Chulhong Kim
Keyword(s):  
Acoustic Imaging ◽  
Signal Frequency ◽  
X Rays ◽  
Repetition Period ◽  
Linear Accelerators ◽  
X Ray ◽  
X Ray Computed ◽  
Medical Linear Accelerators ◽  
Ionizing Radiation Exposure ◽  
X Ray Absorption

AbstractX-ray induced acoustic imaging (XAI) is an emerging biomedical imaging technique that can visualize X-ray absorption contrast at ultrasound resolution with less ionizing radiation exposure than conventional X-ray computed tomography. So far, medical linear accelerators or industrial portable X-ray tubes have been explored as X-ray excitation sources for XAI. Here, we demonstrate the first feasible synchrotron XAI (sXAI). The synchrotron generates X-rays, with a dominant energy of 4 to 30 keV, a pulse-width of 30 ps, a pulse-repetition period of 2 ns, and a bunch-repetition period of 940 ns. The X-ray induced acoustic (XA) signals are processed in the Fourier domain by matching the signal frequency with the bunch-repetition frequency. We successfully obtained two-dimensional XA images of various lead targets. This novel sXAI tool could complement conventional synchrotron applications.

scholarly journals Semi-automated protein crystal mounting device for the sulfur single-wavelength anomalous diffraction method

2010 ◽  
Vol 43 (2) ◽  
pp. 341-346 ◽  
Author(s):  
Yu Kitago ◽  
Nobuhisa Watanabe ◽  
Isao Tanaka
Keyword(s):  
Diffraction Method ◽  
Systematic Errors ◽  
Protein Crystal ◽  
X Rays ◽  
Anomalous Diffraction ◽  
X Ray ◽  
Frozen Solution ◽  
Custom Made ◽  
Protein Molecules ◽  
X Ray Absorption

Use of longer-wavelength X-rays has advantages for the detection of small anomalous signals from light atoms, such as sulfur, in protein molecules. However, the accuracy of the measured diffraction data decreases at longer wavelengths because of the greater X-ray absorption. The capillary-top mounting method (formerly the loopless mounting method) makes it possible to eliminate frozen solution around the protein crystal and reduces systematic errors in the evaluation of small anomalous differences. However, use of this method requires custom-made tools and a large amount of skill. Here, the development of a device that can freeze the protein crystal semi-automatically using the capillary-top mounting method is described. This device can pick up the protein crystal from the crystallization drop using a micro-manipulator, and further procedures, such as withdrawal of the solution around the crystal by suction and subsequent flash freezing of the protein crystal, are carried out automatically. This device makes it easy for structural biologists to use the capillary-top mounting method for sulfur single-wavelength anomalous diffraction phasing using longer-wavelength X-rays.

scholarly journals Anisotropy of X-ray Absorption Cross Section in CeCoGe3 Single Crystal

Crystals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 544
Author(s):  
Andrei Rogalev ◽  
Fabrice Wilhelm ◽  
Elena Ovchinnikova ◽  
Aydar Enikeev ◽  
Roman Bakonin ◽  
...  
Keyword(s):  
Cross Section ◽  
Absorption Cross Section ◽  
Linear Dichroism ◽  
X Rays ◽  
Absorption Cross ◽  
X Ray ◽  
Measured Absorption ◽  
Linearly Polarized ◽  
X Ray Absorption ◽  
Absorption Edges

Absorption spectra of two orthogonal linearly polarized x-rays in a single CeCoGe3 crystal were measured at the ID12 beamline of the ESRF for the energies near the K-edges of Ge, Co and near the L23 edges of Ce. The X-ray natural linear dichroism (XNLD) was revealed in the vicinity of all the absorption edges, which indicates a splitting of electronic states in a crystalline field. Mathematical modelling in comparison with experimental data allowed the isotropic and anisotropic parts of atomic absorption cross section in CeCoGe3 to be determined near all measured absorption edges. The calculations also show that the “average” anisotropy of the cross section close to the Ge K-edge revealed in the experiment is less than the partial anisotropic contributions corresponding to Ge atoms in two different Wyckoff positions.

scholarly journals Pre-edges in oxygen (1s) x-ray absorption spectra: A spectral indicator for electron hole depletion and transport blocking in iron perovskites

2009 ◽  
Vol 94 (20) ◽  
pp. 202102 ◽  
Author(s):  
Artur Braun ◽  
Defne Bayraktar ◽  
Selma Erat ◽  
Ashley S. Harvey ◽  
Daniel Beckel ◽  
...  
Keyword(s):  
Absorption Spectra ◽  
Electron Hole ◽  
X Ray ◽  
X Ray Absorption

X–ray absorption fine structure (XAFS) of Si wafer measured using total reflection X–rays

1999 ◽  
Vol 54 (1) ◽  
pp. 215-222 ◽  
Author(s):  
Jun Kawai ◽  
Shinjiro Hayakawa ◽  
Yoshinori Kitajima ◽  
Yohichi Gohshi
Keyword(s):  
Fine Structure ◽  
Total Reflection ◽  
X Rays ◽  
X Ray ◽  
Absorption Fine ◽  
X Ray Absorption ◽  
Si Wafer

A single crystal, linearly polarized Fe 2p X-ray absorption study of gillespite

1998 ◽  
Vol 62 (1) ◽  
pp. 65-75 ◽  
Author(s):  
P. F. Schofield ◽  
G. van der Laan ◽  
C. M. B. Henderson ◽  
G. Cressey
Keyword(s):  
Single Crystal ◽  
Ground State ◽  
Branching Ratio ◽  
Linear Dichroism ◽  
Electronic Charge ◽  
Magic Angle ◽  
X Rays ◽  
X Ray ◽  
Peak Structure ◽  
X Ray Absorption

AbstractThe Fe 2p X-ray absorption spectra of single crystal gillespite, BaFeSi4O10, show a strong linear dichroism, i.e. a large difference in the absorption when measured with the polarization of the X-rays either parallel or perpendicular to the plane of the FeO4 group. The isotropic spectrum, obtained from measurement at the ‘magic angle’, and the polarization dependent spectra have been compared to atomic multiplet calculations and show an excellent agreement with theory. Analysis of the branching ratio, the linear dichroism, and the detailed peak structure confirms that the 5A1 level is the ground state at room temperature and pressure. The 5B2 level is sufficiently low in energy that a distortion of the electronic charge density, induced by increased pressure, may result in a 5B2 ground state.

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