Elemental, chemical, and orientational characterization of easily damageable materials with x-ray microscopy

1995 ◽  
Vol 53 ◽  
pp. 92-93
Author(s):  
H. Ade
Keyword(s):  
Linear Dichroism ◽  
Aqueous Environment ◽  
X Rays ◽  
Edge Structure ◽  
X Ray ◽  
Elemental Sensitivity ◽  
Linearly Polarized ◽  
Synchrotron Light ◽  
X Ray Absorption

Many of the transmission x-ray microscopy developments since the late seventies, including the ones at the National Synchrotron Light Source (NSLS), were driven primarily by the potential of x-ray microscopy to image wet and unstained biological samples with low radiation dose. High image contrast between an aqueous environment and carbon based materials can be achieved with photon energies between the carbon and oxygen K absorption edges (290-540 eV). This contrast is based on differences in cross section of the elements oxygen and carbon in this energy range. Going beyond this "elemental" sensitivity, Ade et al. recently demonstrated how chemical (valence) sensitivity can be achieved via the X-ray Absorption Near Edge Structure (XANES) at the carbon K edge. In addition, linear dichroism microscopy can exploit the dependence of x-ray absorption resonances on the bond orientation relative to the linearly polarized x rays. For an application of the latter technique see A.P. Smith et al.

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.

Determination of the degree of radial order in Kevlar fibers using x-ray linear dichroism microscopy

1995 ◽  
Vol 53 ◽  
pp. 492-493
Author(s):  
A. P. Smith ◽  
H. Ade ◽  
B. Hsiao ◽  
S. Subramoney
Keyword(s):  
Spatial Resolution ◽  
National Laboratory ◽  
Linear Dichroism ◽  
Fiber Axis ◽  
X Rays ◽  
Specific Chemical ◽  
Edge Structure ◽  
Thin Sections ◽  
X Ray ◽  
X Ray Absorption

The Scanning Transmission X-ray Microscope (STXM) located at beamline X1A at the National Synchrotron Light Source at Brookhaven National Laboratory can be used to acquires high resolution, chemically and orientationally sensitive images with 50 nm spatial resolution, as well as point spectra from 0.1 μm2 areas. Chemical (valence) sensitivity can be achieved via the X-ray Absorption Near Edge Structure (XANES) at the carbon K edge. In addition, linear dichroism microscopy exploits the dependence of x-ray absorption resonances on the bond orientation relative to the linearly polarized x rays. Previous x-ray linear dichroism microscopy work has demonstrated the ability to determine the orientation of specific chemical groups within polymeric systems at high spatial resolution. Here, we have extended this technique to quantitatively determine the degree of radial order in various grades of poly(p-phenylene terephthalamide) (Kevlar™) fibers.The orientational dependence of the absorption cross-section yields “butterfly” patterns when thin sections of certain grades of Kevlar fibers cut at 45° with respect to the fiber axis are imaged at specific photon energies.

X-ray microscopy: A novel, low damage approach to core excitation spectroscopy at high spatial resolution

1996 ◽  
Vol 54 ◽  
pp. 156-157
Author(s):  
H. Ade
Keyword(s):  
Linear Dichroism ◽  
X Rays ◽  
Chemical Mapping ◽  
Specific Chemical ◽  
X Ray ◽  
Nexafs Spectroscopy ◽  
Linearly Polarized ◽  
Imaging Mode ◽  
Electron Energy Loss ◽  
X Ray Absorption

Only recently has transmission x-ray microscopy been utilized for chemical analysis from small spots and chemical mapping via near edge x-ray absorption fine structure (NEXAFS) spectroscopy. NEXAFS microscopy is analogous to Electron Energy Loss Spectroscopy (EELS) in an electron microscope. Particularly in imaging mode, NEXAFS microscopy requires a considerable lower dose than EELS microscopy which makes it very suitable to studying radiation sensitive materials such as polymers. In addition, NEXAFS microscopy can exploit the dependence of x-ray absorption resonances on the bond orientation relative to the linearly polarized x rays (linear dichroism microscopy) and determine the orientation of specific chemical bonds in (partially) orientated materials.

scholarly journals Exploring the Dzi Bead with Synchrotron Light: XRD, XRF Imaging and μ-XANES Analysis

Heritage ◽  
2020 ◽  
Vol 3 (3) ◽  
pp. 1035-1045
Author(s):  
Averie Reinhardt ◽  
Renfei Feng ◽  
Qunfeng Xiao ◽  
Yongfeng Hu ◽  
Tsun-Kong Sham
Keyword(s):  
Hot Spots ◽  
Imaging Techniques ◽  
X Rays ◽  
X Ray Diffraction ◽  
Edge Structure ◽  
X Ray ◽  
Synchrotron Light ◽  
Evil Spirits ◽  
Eye Pattern ◽  
X Ray Absorption

The origin of Dzi beads, also called “tian zhu”, has always been a mystery. These beads come in a variety of patterns, shapes and sizes. They have cultural and heritage significance in Tibet and areas surrounding the Himalayas. The most recognized beads are those with the “eye” pattern. They are said to ward off evil spirits. Due to their reputation, the demand for Dzi beads has increased in Asia. Herein, we report a study of a Dzi bead with a three-eye pattern using X-ray diffraction (XRD), X-ray fluorescence (XRF), X-ray absorption near edge structure (XANES) and imaging techniques. This is a novel area for Dzi bead research using X-rays from a synchrotron light source to determine the chemical composition of the bead, if the pattern is natural or man-made or if the bead is genuine or a replica. These techniques revealed the bead to be composed of agate (silicon dioxide). An interesting feature on the bead’s surface was the etched rings, which were observed to contain regular copper hot spots on their circumference. Our results suggest that the Dzi bead was genuine and started out as an earth-formed agate, with the pattern crafted.

scholarly journals Database of ab initio L-edge X-ray absorption near edge structure

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Yiming Chen ◽  
Chi Chen ◽  
Chen Zheng ◽  
Shyam Dwaraknath ◽  
Matthew K. Horton ◽  
...  
Keyword(s):  
High Throughput ◽  
Scattering Theory ◽  
Research Community ◽  
Metal Compounds ◽  
Edge Structure ◽  
X Ray ◽  
Initial Release ◽  
Computational Workflow ◽  
X Ray Absorption

AbstractThe L-edge X-ray Absorption Near Edge Structure (XANES) is widely used in the characterization of transition metal compounds. Here, we report the development of a database of computed L-edge XANES using the multiple scattering theory-based FEFF9 code. The initial release of the database contains more than 140,000 L-edge spectra for more than 22,000 structures generated using a high-throughput computational workflow. The data is disseminated through the Materials Project and addresses a critical need for L-edge XANES spectra among the research community.

Characterization of As-doped, p-type ZnO by x-ray absorption near-edge structure spectroscopy: Theory

2006 ◽  
Vol 89 (22) ◽  
pp. 222113 ◽  
Author(s):  
Sukit Limpijumnong ◽  
M. F. Smith ◽  
S. B. Zhang
Keyword(s):  
Edge Structure ◽  
X Ray ◽  
P Type ◽  
X Ray Absorption

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.

Near Edge X-Ray Absorption Fine Structure (NEXAFS) Microscopy: Chemical Analysis at Sub Visible Spatial Resolution

1997 ◽  
Vol 3 (S2) ◽  
pp. 851-852
Author(s):  
H. Ade
Keyword(s):  
Fine Structure ◽  
Compositional Analysis ◽  
High Sensitivity ◽  
Linear Dichroism ◽  
X Rays ◽  
X Ray ◽  
Absorption Fine ◽  
Nexafs Spectroscopy ◽  
Wide Range ◽  
X Ray Absorption

Infrared, Raman, and fluorescence/luminescence microspectroscopy/microscopy in many instances seek to provide high sensitivity compositional and functional information that goes beyond mere elemental composition. This goal is shared by NEXAFS microscopy, in which Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy is employed to provide chemical sensitivity and can be relatively easily adopted in a scanning transmission x-ray microscope (STXM). In addition to compositional information, NEXAFS microscopy can exploit the dependence of x-ray absorption resonances on the bond orientation relative to the linearly polarized x rays (linear dichroism microscopy). For compositional analysis, NEXAFS microscopy is analogous to Electron Energy Loss Spectroscopy (EELS) in an electron microscope. However, when utilizing near edge spectral features, NEXAFS microscopy requires a considerable lower dose than EELS microscopy which makes it very suitable to studying radiation sensitive materials such as polymers. NEXAFS has shown to have excellent sensitivity to a wide range of moieties in polymers, including sensitivity to substitution isomerism.

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