Development of XANES nanoscopy on BL7C at PLS-II

X-ray absorption near-edge structure (XANES) imaging is a powerful tool to visualize the chemical state distribution of transition-metal-based materials at synchrotron radiation facilities. In recent years, the electrochemical working rechargeable battery has been the most studied material in XANES imaging owing to the large increase of portable electronics and electric vehicles. This work acknowledges the importance of battery analysis and has developed the XANES imaging system on BL7C at Pohang Light Source-II (PLS-II). BL7C employs an undulator taper configuration to obtain an energy band >130 eV near the K-absorption edge of the target element with a minimum energy interval >0.2 eV. While measuring energy-dependent images, the zone plate translation maintains the best focus, and then various data processes such as background correction, image registration and clustering allow single XANES spectrum extraction and chemical distribution mapping. Here, the XANES imaging process is described, the XANES spectrum quality is identified and the chemical states of the partially charged cathode material used in lithium-ion batteries as an application example are examined.

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Early commissioning results for spectroscopic X-ray Nano-Imaging Beamline BL 7C sXNI at PLS-II

Journal of Synchrotron Radiation ◽

10.1107/s1600577517013972 ◽

2017 ◽

Vol 24 (6) ◽

pp. 1276-1282 ◽

Cited By ~ 8

Author(s):

Sangsul Lee ◽

Ik hwan Kwon ◽

Jae-Young Kim ◽

Sung-Sun Yang ◽

Sechang Kang ◽

...

Keyword(s):

Lithium Iron Phosphate ◽

Phase Distribution ◽

Lithium Ion ◽

Feedback System ◽

Double Crystal ◽

Pilot Studies ◽

Beam Position ◽

Edge Structure ◽

X Ray

For spectral imaging of chemical distributions using X-ray absorption near-edge structure (XANES) spectra, a modified double-crystal monochromator, a focusing plane mirrors system and a newly developed fluorescence-type X-ray beam-position monitoring and feedback system have been implemented. This major hardware upgrade provides a sufficiently stable X-ray source during energy scanning of more than hundreds of eV for acquisition of reliable XANES spectra in two-dimensional and three-dimensional images. In recent pilot studies discussed in this paper, heavy-metal uptake by plant rootsin vivoand iron's phase distribution in the lithium–iron–phosphate cathode of a lithium-ion battery have been imaged. Also, the spatial resolution of computed tomography has been improved from 70 nm to 55 nm by means of run-out correction and application of a reconstruction algorithm.

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Parameters Influencing Sulfur Speciation in Environmental Samples Using Sulfur K-Edge X-Ray Absorption Near-Edge Structure

Journal of Analytical Methods in Chemistry ◽

10.1155/2012/659858 ◽

2012 ◽

Vol 2012 ◽

pp. 1-12 ◽

Cited By ~ 2

Author(s):

Siwatt Pongpiachan ◽

Kanjana Thumanu ◽

Charnwit Kositanont ◽

Klaus Schwarzer ◽

Jörg Prietzel ◽

...

Keyword(s):

Environmental Samples ◽

Sulfur Compound ◽

Germanium Detector ◽

Xanes Spectrum ◽

Principal Component ◽

Hierarchical Cluster ◽

Particle Size Effect ◽

Coastal Sediments ◽

Signal To Noise ◽

Edge Structure

This paper aims to enhance the credibility of applying the sulfur K-edge XANES spectroscopy as an innovative “fingerprint” for characterizing environmental samples. The sensitivities of sulfur K-edge XANES spectra of ten sulfur compound standards detected by two different detectors, namely, Lytle detector (LyD) and Germanium detector (GeD), were studied and compared. Further investigation on “self-absorption” effect revealed that the maximum sensitivities of sulfur K-edge XANES spectra were achieved when diluting sulfur compound standards with boron nitride (BN) at the mixing ratio of 0.1%. The “particle-size” effect on sulfur K-edge XANES spectrum sensitivities was examined by comparing signal-to-noise ratios of total suspended particles (TSP) and particulate matter of less than 10 millionths of a meter(PM10)collected at three major cities of Thailand. The analytical results have demonstrated that the signal-to-noise ratios of sulfur K-edge XANES spectra were positively correlated with sulfate content in aerosols and negatively connected with particle sizes. The combination of hierarchical cluster analysis (HCA) and principal component analysis (PCA) has proved that sulfur K-edge XANES spectrum can be used to characterize German terrestrial soils and Andaman coastal sediments. In addition, this study highlighted the capability of sulfur K-edge XANES spectra as an innovative “fingerprint” to distinguish tsunami backwash deposits (TBD) from typical marine sediments (TMS).

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The dynamics of the inner boundary of the outer radiation belt during geomagnetic storms

10.5194/egusphere-egu2020-19607 ◽

2020 ◽

Author(s):

Xiaofei Shi ◽

Jie Ren ◽

Qiugang Zong

Keyword(s):

Radiation Belt ◽

Electron Flux ◽

Geomagnetic Storms ◽

Minimum Energy ◽

Onset Time ◽

Recovery Phase ◽

Outer Radiation Belt ◽

H Index ◽

Late Recovery ◽

Energy Dependent

We present a statistical study of energy-dependent and L shell-dependent inner boundary of the outer radiation belt during 37 isolated geomagnetic storms using observations from Van Allen Probes from 2013 to 2017. There are mutual transformations between "V-shaped" and "S-shaped" inner boundaries during different storm phases, resulting from the competition among electron loss, radial transport and local acceleration. The radial position, onset time, Est (the minimum energy at Lst where the inner boundary starts to exhibit an S-shaped form), and the radial width of S-shaped boundary (&#916;L) are quantitatively defined according to the formation of a reversed energy spectrum (electron flux going up with increasing energies from hundreds of keV to ~1 MeV) from a kappa-like spectrum (electron flux steeply falling with increasing energies). The case and statistical results present that (1) The inner boundary has repeatable features associated with storms: the inner boundary is transformed from S-shaped to V-shaped form in several hours during the storm commencement and main phase, and retains in the V-shaped form for several days until it evolves into S-shaped during late recovery phase; (2) &#916;L shows positive correlation with SYM-H index; (3) The duration of the V-shaped form is positively correlated with the storm intensity and the duration of the recovery phase; (4) The minimum energy Est are mainly distributed in the range of 100-550 keV. All these findings have important implications for understanding the dynamics of energetic electrons in the slot region and the outer radiation belt during geomagnetic storms.

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Electronic Structure of P-Doped ZnO Films with p-Type Conductivity

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2006.17953 ◽

2006 ◽

Vol 6 (11) ◽

pp. 3422-3425

Author(s):

Veeramuthu Vaithianathan ◽

Jong Ha Moon ◽

Chang-Hwan Chang ◽

Kandasami Asokan ◽

Sang Sub Kim

Keyword(s):

Electronic Structure ◽

Xanes Spectrum ◽

Sharp Decrease ◽

Zno Films ◽

Charge Neutrality ◽

Edge Structure ◽

X Ray ◽

Doped Zno ◽

P Type ◽

X Ray Absorption

The electronic structure of laser-deposited P-doped ZnO films was investigated by X-ray absorption near-edge structure spectroscopy (XANES) at the O K-, Zn K-, and Zn L3-edges. While the O K-edge XANES spectrum of the n-type P-doped ZnO demonstrates that the density of unoccupied states, primarily O 2p–P 3sp hybridized states, is significantly high, the O K-edge XANES spectrum of the p-type P-doped ZnO shows a sharp decrease in intensity of the corresponding feature indicating that P replaces O sites in the ZnO lattice, and thereby generating PO. This produces holes to maintain charge neutrality that are responsible for the p-type behavior of P-doped ZnO. Both the Zn K-, and Zn L3-edge XANES spectra of the P-doped ZnO reveal that Zn plays no significant role in the p-type behavior of ZnO:P.

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X-ray absorption near edge structure analysis of the charge–discharge mechanisms of dithiobiuret polymer used as a high-capacity cathode material for lithium-ion batteries

Electrochimica Acta ◽

10.1016/j.electacta.2018.05.137 ◽

2018 ◽

Vol 281 ◽

pp. 99-108 ◽

Cited By ~ 1

Author(s):

Hiroshi Uemachi ◽

Yuske Tamenori ◽

Tetsuya Itono ◽

Takashi Masuda ◽

Tatsuya Shimoda ◽

...

Keyword(s):

Cathode Material ◽

Lithium Ion Batteries ◽

Structure Analysis ◽

High Capacity ◽

Lithium Ion ◽

Edge Structure ◽

X Ray ◽

X Ray Absorption ◽

Charge Discharge

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Effect of thickness variations on EELS spatial-difference profiles

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100165288 ◽

1996 ◽

Vol 54 ◽

pp. 564-565

Author(s):

J. Bruley ◽

D. B. Williams

Keyword(s):

Difference Spectrum ◽

Spatial Difference ◽

Probe Position ◽

Difference Spectra ◽

Characteristic Structure ◽

Edge Structure ◽

Dependent Signal ◽

The Difference ◽

Thickness Variations ◽

Energy Dependent

This paper concerns the influence of sample thickness on spatial-difference spectra, and seeks to identify if an interface dependent signal may be generated as an artifact of grain boundary grooving. The spatial-difference profiling technique may be used to identify variations in composition and electronic structure across interfaces at sub-nanometer length scales. The signal-to-background ratios and hence visibility of small changes to the near-edge structure and edge intensities are enhanced using this technique by removing intense energy dependent backgrounds. These backgrounds are assumed to be only slowly varying with respect to the electron probe position. A spatial-difference spectrum is generated from the difference between two spectra after suitable normalization or scaling. This scaling is achieved by either matching intensities of the background prior to a characteristic absorption edge (for compositional profiles) or by normalizing to some characteristic structure of the near-edge structure (for bonding profiles). The latter is performed typically after subtraction of a smooth power-law background modeled in the region immediately preceding the edge.

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In Situ X-ray Absorption Near-Edge Structure Calculation and Machine Learning Analysis of the Structural Evolution in Lithium-Ion Battery Cathode Materials

The Journal of Physical Chemistry C ◽

10.1021/acs.jpcc.1c05810 ◽

2021 ◽

Author(s):

Ji Li ◽

Bingbao Mei ◽

Hongzhou Liu ◽

Xuewen Li ◽

Songqi Gu ◽

...

Keyword(s):

Machine Learning ◽

Cathode Materials ◽

Structural Evolution ◽

Lithium Ion ◽

Structure Calculation ◽

Edge Structure ◽

X Ray ◽

X Ray Absorption ◽

Learning Analysis

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An Analytical Model for Adsorption and Diffusion of Atoms/Ions on Graphene Surface

Journal of Nanomaterials ◽

10.1155/2015/382474 ◽

2015 ◽

Vol 2015 ◽

pp. 1-10 ◽

Cited By ~ 3

Author(s):

Yan-Zi Yu ◽

Jian-Gang Guo ◽

Yi-Lan Kang

Keyword(s):

Interaction Energy ◽

Minimum Energy ◽

Gold Atom ◽

Lithium Ion ◽

Continuous Model ◽

Atomic Scale ◽

Monolayer Graphene ◽

Graphene Surface ◽

Adsorption Sites ◽

And Diffusion

Theoretical investigations are made on adsorption and diffusion of atoms/ions on graphene surface based on an analytical continuous model. An atom/ion interacts with every carbon atom of graphene through a pairwise potential which can be approximated by the Lennard-Jones (L-J) potential. Using the Fourier expansion of the interaction potential, the total interaction energy between the adsorption atom/ion and a monolayer graphene is derived. The energy-distance relationships in the normal and lateral directions for varied atoms/ions, including gold atom (Au), platinum atom (Pt), manganese ion (Mn2+), sodium ion (Na1+), and lithium-ion (Li1+), on monolayer graphene surface are analyzed. The equilibrium position and binding energy of the atoms/ions at three particular adsorption sites (hollow, bridge, and top) are calculated, and the adsorption stability is discussed. The results show that H-site is the most stable adsorption site, which is in agreement with the results of other literatures. What is more, the periodic interaction energy and interaction forces of lithium-ion diffusing along specific paths on graphene surface are also obtained and analyzed. The minimum energy barrier for diffusion is calculated. The possible applications of present study include drug delivery system (DDS), atomic scale friction, rechargeable lithium-ion graphene battery, and energy storage in carbon materials.

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Machine learning approaches for ELNES/XANES

Microscopy ◽

10.1093/jmicro/dfz109 ◽

2020 ◽

Vol 69 (2) ◽

pp. 92-109 ◽

Cited By ~ 1

Author(s):

Teruyasu Mizoguchi ◽

Shin Kiyohara

Keyword(s):

Neural Network ◽

Machine Learning ◽

Decision Tree ◽

Hierarchical Clustering ◽

Data Augmentation ◽

Xanes Spectrum ◽

Feedforward Neural Network ◽

Material Structure ◽

Learning Approaches ◽

Edge Structure

Abstract Materials characterization is indispensable for materials development. In particular, spectroscopy provides atomic configuration, chemical bonding and vibrational information, which are crucial for understanding the mechanism underlying the functions of a material. Despite its importance, the interpretation of spectra using human-driven methods, such as manual comparison of experimental spectra with reference/simulated spectra, is becoming difficult owing to the rapid increase in experimental spectral data. To overcome the limitations of such methods, we develop new data-driven approaches based on machine learning. Specifically, we use hierarchical clustering, a decision tree and a feedforward neural network to investigate the electron energy loss near edge structures (ELNES) spectrum, which is identical to the X-ray absorption near edge structure (XANES) spectrum. Hierarchical clustering and the decision tree are used to interpret and predict ELNES/XANES, while the feedforward neural network is used to obtain hidden information about the material structure and properties from the spectra. Further, we construct a prediction model that is robust against noise by data augmentation. Finally, we apply our method to noisy spectra and predict six properties accurately. In summary, the proposed approaches can pave the way for fast and accurate spectrum interpretation/prediction as well as local measurement of material functions.

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