scholarly journals Effect of reflection and refraction on NEXAFS spectra measured in TEY mode

2018 ◽  
Vol 25 (1) ◽  
pp. 232-240 ◽  
Author(s):  
Elena Filatova ◽  
Andrey Sokolov
Keyword(s):  
Critical Angle ◽  
Optical Constants ◽  
Reflection Spectroscopy ◽  
Total Electron Yield ◽  
Total Electron ◽  
X Ray ◽  
Reflection And Refraction ◽  
Wide Range ◽  
X Ray Absorption ◽  
Kronig Relation

The evolution of near-edge X-ray absorption fine structure in the vicinity of theK-absorption edge of oxygen for HfO2over a wide range of incidence angles is analyzed by simultaneous implementation of the total-electron-yield (TEY) method and X-ray reflection spectroscopy. It is established that the effect of refraction on the TEY spectrum is greater than that of reflection and extends into the angular region up to angles 2θc. Within angles that are less than the critical angle, both the reflection and refraction strongly distort the shape of the TEY spectrum. Limitations of the technique for the calculation of optical constants from the reflection spectra using the Kramers–Kronig relation in the limited energy region in the vicinity of thresholds are discussed in detail.

Determination of the Anomalous Scattering Factors in the Soft-X-ray Range using Diffraction from a Multilayer

1998 ◽  
Vol 31 (5) ◽  
pp. 700-707 ◽  
Author(s):  
L. Sève ◽  
J. M. Tonnerre ◽  
D. Raoux
Keyword(s):  
Fluorescence Yield ◽  
Bragg Diffraction ◽  
Anomalous Scattering ◽  
Total Electron Yield ◽  
Total Electron ◽  
X Ray ◽  
Scattering Factor ◽  
X Ray Absorption ◽  
Kronig Relation

Bragg diffraction from an Ag/Ni multilayer was used to determine independently both the real and imaginary parts of the anomalous scattering factor (ASF) around the NiLIIIandLIIedges in the soft-X-ray range. Huge resonant variations were observed with f'' reaching 55\,r_o and f' decreasing to −63 r_o at the NiLIIIedge. The independent measurements of f' and f'' are tested for coherency using the Kramers–Kronig relation. The f'' values are also compared with those derived from X-ray absorption methods such as total electron yield and fluorescence yield measurements.

Soft X-ray refractive index by reconciling total electron yield with specular reflection: experimental determination of the optical constants of graphite

2018 ◽  
Vol 25 (5) ◽  
pp. 1433-1443
Author(s):  
C. Jansing ◽  
H. Wahab ◽  
H. Timmers ◽  
A. Gaupp ◽  
H.-C. Mertins
Keyword(s):  
Refractive Index ◽  
Optical Constants ◽  
Specular Reflection ◽  
Complex Refractive Index ◽  
Reflection Spectra ◽  
Total Electron Yield ◽  
Total Electron ◽  
X Ray ◽  
Electron Yield ◽  
Saturation Effects

The complex refractive index of many materials is poorly known in the soft X-ray range across absorption edges. This is due to saturation effects that occur there in total-electron-yield and fluorescence-yield spectroscopy and that are strongest at resonance energies. Aiming to obtain reliable optical constants, a procedure that reconciles electron-yield measurements and reflection spectroscopy by correcting these saturation effects is presented. The procedure takes into account the energy- and polarization-dependence of the photon penetration depth as well as the creation efficiency for secondary electrons and their escape length. From corrected electron-yield spectra the absorption constants and the imaginary parts of the refractive index of the material are determined. The real parts of the index are subsequently obtained through a Kramers–Kronig transformation. These preliminary optical constants are refined by simulating reflection spectra and adapting them, so that measured reflection spectra are reproduced best. The efficacy of the new procedure is demonstrated for graphite. The optical constants that have been determined for linearly polarized synchrotron light incident with p- and s-geometry provide a detailed and reliable representation of the complex refractive index of the material near π- and σ-resonances. They are also suitable for allotropes of graphite such as graphene.

Short Range Order Structure Around Oxygen Atoms in the Superconductor Y-Ba-Cu-O

1987 ◽  
Vol 99 ◽  
Author(s):  
S. C. Woronick ◽  
W. Ng ◽  
A. Krol ◽  
B. X. Yang ◽  
Y. H. Kao ◽  
...  
Keyword(s):  
Short Range ◽  
Short Range Order ◽  
Local Environment ◽  
Order Structure ◽  
Total Electron Yield ◽  
Total Electron ◽  
X Ray ◽  
Superconducting Compound ◽  
X Ray Absorption ◽  
Oxygen Atoms

ABSTRACTSpectra of the oxygen K-edge extended x-ray absorption fine structure (EXAFS) of the superconducting compound Y-Ba-Cu-O were obtained by measuring the total electron yield as a function of incident x-ray energy at temperatures between 77K and 300K. This technique affords a convenient way for probing the local environment around the oxygen atoms and soft modes in the lattice.

VUV- and Soft X-Ray-Induced Optical Luminescence and X-Ray Absorption Fine Structures of Porous Silicon

1992 ◽  
Vol 281 ◽  
Author(s):  
T. K. Sham ◽  
D. T. Jiang ◽  
I. Coulthard ◽  
J. W. Lorimer ◽  
X. H. Feng ◽  
...  
Keyword(s):  
Porous Silicon ◽  
Total Electron Yield ◽  
Total Electron ◽  
X Ray ◽  
Absorption Fine ◽  
Electron Yield ◽  
Optical Luminescence ◽  
Fine Structures ◽  
X Ray Absorption ◽  
Uv Excitation

ABSTRACTOptical luminescence in porous silicon induced by soft X-ray and vacuum UV excitation with energies in the vicinity of the Si K-edge (1838 eV) and the Si L-edge (99 eV) has been observed. The luminescence has been used, together with total electron yield, to record X-ray absorption fine structure (XAFS) in the near-edge region of both Si edges. The near- edge spectra recorded simultaneously with either luminescence or total electron yield were compared, and the implications of these measurements for the structure of porous silicon are discussed.

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