Study of X-ray absorption near-edge structure with a photoemission electron microscope

2006 ◽  
Vol 38 (4) ◽  
pp. 574-578
Author(s):  
Zengming Zhang ◽  
Zejun Ding ◽  
Hideki Yoshikawa ◽  
Ryuichi Shimizu
Keyword(s):  
Electron Microscope ◽  
Edge Structure ◽  
X Ray ◽  
X Ray Absorption ◽  
Photoemission Electron

X-RAY PHOTOEMISSION ELECTRON MICROSCOPE DETERMINATION OF ORIGINS OF ROOM TEMPERATURE FERROMAGNETISM AND PHOTOLUMINESCENCE IN HIGH Co-CONTENT CoxZn1-xO FILMS

2014 ◽  
Vol 21 (04) ◽  
pp. 1450058 ◽  
Author(s):  
WEI CAO ◽  
VLADIMIR PANKRATOV ◽  
MARKO HUTTULA ◽  
LIANA SHIRMANE ◽  
YU RAN NIU ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Room Temperature ◽  
Room Temperature Ferromagnetism ◽  
Luminescence Properties ◽  
Edge Structure ◽  
X Ray ◽  
Zno Nanoclusters ◽  
X Ray Absorption ◽  
Photoemission Electron

In this paper, we reported on the X-ray photoemission electron microscope (XPEEM) determination of magnetic and luminescence origins for two Co x Zn 1-x O films. The cobalt fraction x of radio frequency co-sputtered samples were 0.86(2) and 0.92(2), respectively. Films were ferromagnetic and semiconductive. Unique narrow green color lines beside the ZnO intrinsic emissions were found with a decay time in microsecond range at room temperature. Origins of magnetic and luminescence properties were determined with XPEEM. The X-ray absorption near edge structure at the Co  L3-edge denoted that Co was partially oxidized, and phase-contrast images together with chemical composition identification further proved that Co and CoO co-existed in the samples. The ferromagnetism was attributed to ferromagnetism of Co clusters partially canceled by the antiferromagnetism of its oxide, and the photoluminescence to bound exciton in ZnO nanoclusters and defect related centers of ZnO nanoclusters in a Co -rich matrix. Present results show possibilities for adjusting magnetic and luminescence properties of Co – ZnO compounds by changing the cobalt concentration.

Calculations of oxygen electron energy loss near edge structure

1987 ◽  
Vol 45 ◽  
pp. 128-129
Author(s):  
Xudong Weng ◽  
Peter Rez
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Energy Loss ◽  
Electron Energy ◽  
Nearest Neighbour ◽  
Edge Structure ◽  
X Ray ◽  
Electron Energy Loss ◽  
X Ray Absorption ◽  
Widespread Interest

Most analytical microscopes are equipped with energy loss spectrometers capable of giving spectra showing 1-2 eV resolution for inner shell edges. The relatively weak modulation starting 30-50 eV from threshold due to Extended X-ray Edge Energy Loss Fine Structure (EXELFS) which is analogous to EXAFS in X-ray absorption has been studied in some detail. Although the theory is, in principle, straightforward the technique using energy loss in the electron microscope to determine nearest neighbour distances has not attracted widespread interest. This is partly due to the long counting times involved. The near edge structure (NES) within 20-30 eV of threshold is characterized by a very strong modulation and is clearly visible even when small amounts of the element are present. Interpretation of the features is very much more difficult and except in those cases in which peaks can be clearly assigned to transitions to antibonding orbitals the main form of analysis has been limited to simple comparisons or fingerprinting.

ACTIVE-ILMENITE SURFACE STRUCTURE INFLUENCE ON ACID-ASSISTED BALL MILLING

2018 ◽  
Vol 25 (Supp01) ◽  
pp. 1840006
Author(s):  
WEERACHON PHOOHINKONG ◽  
SORAPONG PAVASUPREE ◽  
KANOKTHIP BOONYARATTANAKALIN ◽  
WANICHAYA MEKPRASART ◽  
WISANU PECHARAPA
Keyword(s):  
Electron Microscope ◽  
Ball Milling ◽  
Sample Surface ◽  
Chemical Oxidation ◽  
Milling Process ◽  
Octahedral Cluster ◽  
Edge Structure ◽  
X Ray ◽  
Ball Milling Process ◽  
X Ray Absorption

Active-ilmenite powder derived from natural ilmenite sand was prepared by the ball milling process with acid-solution and Deionized (DI) water. Morphology and particle size of active-ilmenite product in acid/DI-assisted ball milling process were monitored by field emission scanning electron microscope (FE-SEM) and transmission electron microscope (TEM). Surface atomic component and chemical bonding were investigated by X-ray photoelectron spectroscopy (XPS). Meanwhile, bulk chemical oxidation and fine structure of active-ilmenite were studied by X-ray absorption near edge structure (XANES) and extended X-ray absorption ne-structure spectroscopy (EXAFS) to confirm the oxidation state and local active species structure at surface. Active-ilmenite by acid-assisted ball milling process is a distinctive method for the preparation of active-ilmenite product with high active surface. Moreover, the distortion of TiO6 and FeO6 octahedral cluster on the sample surface was detected in all milled samples with acid-assisted ball milling process. The presence of Fe[Formula: see text], Fe[Formula: see text] ions and miniature sulfate was also detected on the sample surface by milled product with acid-assisted method.

X-ray microanalysis of thin specimens in the transmission electron microscope at voltages up to 1000 Kv.

1978 ◽  
Vol 36 (1) ◽  
pp. 540-541
Author(s):  
G. Cliff ◽  
M.J. Nasir ◽  
G.W. Lorimer ◽  
N. Ridley
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Weight Fraction ◽  
Present Series ◽  
Constant Independent ◽  
X Ray ◽  
Transmission Electron ◽  
Series Of Experiments ◽  
Image Position ◽  
X Ray Absorption

In a specimen which is transmission thin to 100 kV electrons - a sample in which X-ray absorption is so insignificant that it can be neglected and where fluorescence effects can generally be ignored (1,2) - a ratio of characteristic X-ray intensities, I1/I2 can be converted into a weight fraction ratio, C1/C2, using the equationwhere k12 is, at a given voltage, a constant independent of composition or thickness, k12 values can be determined experimentally from thin standards (3) or calculated (4,6). Both experimental and calculated k12 values have been obtained for K(11<Z>19),kα(Z>19) and some Lα radiation (3,6) at 100 kV. The object of the present series of experiments was to experimentally determine k12 values at voltages between 200 and 1000 kV and to compare these with calculated values.The experiments were carried out on an AEI-EM7 HVEM fitted with an energy dispersive X-ray detector.

point-Analysis Using the Extrapolation Method in the Analytical Electron microscope

1990 ◽  
Vol 48 (2) ◽  
pp. 430-431
Author(s):  
Zenji Horita ◽  
Ryuzo Nishimachi ◽  
Takeshi Sano ◽  
Minoru Nemoto
Keyword(s):  
Electron Microscope ◽  
Extrapolation Method ◽  
X Ray ◽  
Absorption Correction ◽  
Point Analysis ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
Data Points ◽  
Identical Composition ◽  
X Ray Absorption

Absorption correction is often required in quantitative x-ray microanalysis of thin specimens using the analytical electron microscope. For such correction, it is convenient to use the extrapolation method[l] because the thickness, density and mass absorption coefficient are not necessary in the method. The characteristic x-ray intensities measured for the analysis are only requirement for the absorption correction. However, to achieve extrapolation, it is imperative to obtain data points more than two at different thicknesses in the identical composition. Thus, the method encounters difficulty in analyzing a region equivalent to beam size or the specimen with uniform thickness. The purpose of this study is to modify the method so that extrapolation becomes feasible in such limited conditions. Applicability of the new form is examined by using a standard sample and then it is applied to quantification of phases in a Ni-Al-W ternary alloy.The earlier equation for the extrapolation method was formulated based on the facts that the magnitude of x-ray absorption increases with increasing thickness and that the intensity of a characteristic x-ray exhibiting negligible absorption in the specimen is used as a measure of thickness.

Chemical and orientational imaging of polymeric samples

1994 ◽  
Vol 52 ◽  
pp. 68-69
Author(s):  
H. Ade ◽  
B. Hsiao ◽  
G. Mitchell ◽  
E. Rightor ◽  
A. P. Smith ◽  
...  
Keyword(s):  
Ethylene Terephthalate ◽  
National Laboratory ◽  
Brookhaven National Laboratory ◽  
Carbonyl Groups ◽  
Aromatic Rings ◽  
Edge Structure ◽  
X Ray ◽  
Scanning Transmission ◽  
Polymeric Samples ◽  
X Ray Absorption

We have used the Scanning Transmission X-ray Microscope at beamline X1A (X1-STXM) at Brookhaven National Laboratory (BNL) to acquire high resolution, chemical and orientation sensitive images of polymeric samples as well as point spectra from 0.1 μm areas. This sensitivity is achieved by exploiting the X-ray Absorption Near Edge Structure (XANES) of the carbon K edge. One of the most illustrative example of the chemical sensitivity achievable is provided by images of a polycarbonate/pol(ethylene terephthalate) (70/30 PC/PET) blend. Contrast reversal at high overall contrast is observed between images acquired at 285.36 and 285.69 eV (Fig. 1). Contrast in these images is achieved by exploring subtle differences between resonances associated with the π bonds (sp hybridization) of the aromatic groups of each polymer. PET has a split peak associated with these aromatic groups, due to the proximity of its carbonyl groups to its aromatic rings, whereas PC has only a single peak.

Full-Field Calcium K-Edge X-ray Absorption Near-Edge Structure Spectroscopy on Cortical Bone at the Micron-Scale: Polarization Effects Reveal Mineral Orientation

2016 ◽  
Vol 88 (7) ◽  
pp. 3826-3835 ◽  
Author(s):  
Bernhard Hesse ◽  
Murielle Salome ◽  
Hiram Castillo-Michel ◽  
Marine Cotte ◽  
Barbara Fayard ◽  
...  
Keyword(s):  
Cortical Bone ◽  
Edge Structure ◽  
Full Field ◽  
Polarization Effects ◽  
X Ray ◽  
X Ray Absorption

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.

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