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Title: Rotation of X-ray polarization in the glitches of a silicon crystal monochromator

Abstract

EXAFS studies on dilute samples are usually carried out by collecting the fluorescence yield using a large-area multi-element detector. This method is susceptible to the `glitches' produced by all single-crystal monochromators. Glitches are sharp dips or spikes in the diffracted intensity at specific crystal orientations. If incorrectly compensated, they degrade the spectroscopic data. Normalization of the fluorescence signal by the incident flux alone is sometimes insufficient to compensate for the glitches. Measurements performed at the state-of-the-art wiggler beamline I20-scanning at Diamond Light Source have shown that the glitches alter the spatial distribution of the sample's quasi-elastic X-ray scattering. Because glitches result from additional Bragg reflections, multiple-beam dynamical diffraction theory is necessary to understand their effects. Here, the glitches of the Si(111) four-bounce monochromator of I20-scanning just above the Ni Kedge are associated with their Bragg reflections. A fitting procedure that treats coherent and Compton scattering is developed and applied to a sample of an extremely dilute (100 micromolal) aqueous solution of Ni(NO 3) 2. The depolarization of the wiggler X-ray beam out of the electron orbit is modeled. The fits achieve good agreement with the sample's quasi-elastic scattering with just a few parameters. The X-ray polarization is rotated up tomore » ±4.3° within the glitches, as predicted by dynamical diffraction. These results will help users normalize EXAFS data at glitches.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
Diamond Light Source, UK
OSTI Identifier:
1376895
DOE Contract Number:  
AC02-06CH11357
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Crystallography (Online); Journal Volume: 49; Journal Issue: 4
Country of Publication:
United States
Language:
English

Citation Formats

Sutter, John P., Boada, Roberto, Bowron, Daniel T., Stepanov, Sergey A., and Díaz-Moreno, Sofía. Rotation of X-ray polarization in the glitches of a silicon crystal monochromator. United States: N. p., 2016. Web. doi:10.1107/S1600576716009183.
Sutter, John P., Boada, Roberto, Bowron, Daniel T., Stepanov, Sergey A., & Díaz-Moreno, Sofía. Rotation of X-ray polarization in the glitches of a silicon crystal monochromator. United States. doi:10.1107/S1600576716009183.
Sutter, John P., Boada, Roberto, Bowron, Daniel T., Stepanov, Sergey A., and Díaz-Moreno, Sofía. Wed . "Rotation of X-ray polarization in the glitches of a silicon crystal monochromator". United States. doi:10.1107/S1600576716009183.
@article{osti_1376895,
title = {Rotation of X-ray polarization in the glitches of a silicon crystal monochromator},
author = {Sutter, John P. and Boada, Roberto and Bowron, Daniel T. and Stepanov, Sergey A. and Díaz-Moreno, Sofía},
abstractNote = {EXAFS studies on dilute samples are usually carried out by collecting the fluorescence yield using a large-area multi-element detector. This method is susceptible to the `glitches' produced by all single-crystal monochromators. Glitches are sharp dips or spikes in the diffracted intensity at specific crystal orientations. If incorrectly compensated, they degrade the spectroscopic data. Normalization of the fluorescence signal by the incident flux alone is sometimes insufficient to compensate for the glitches. Measurements performed at the state-of-the-art wiggler beamline I20-scanning at Diamond Light Source have shown that the glitches alter the spatial distribution of the sample's quasi-elastic X-ray scattering. Because glitches result from additional Bragg reflections, multiple-beam dynamical diffraction theory is necessary to understand their effects. Here, the glitches of the Si(111) four-bounce monochromator of I20-scanning just above the Ni Kedge are associated with their Bragg reflections. A fitting procedure that treats coherent and Compton scattering is developed and applied to a sample of an extremely dilute (100 micromolal) aqueous solution of Ni(NO3)2. The depolarization of the wiggler X-ray beam out of the electron orbit is modeled. The fits achieve good agreement with the sample's quasi-elastic scattering with just a few parameters. The X-ray polarization is rotated up to ±4.3° within the glitches, as predicted by dynamical diffraction. These results will help users normalize EXAFS data at glitches.},
doi = {10.1107/S1600576716009183},
journal = {Journal of Applied Crystallography (Online)},
number = 4,
volume = 49,
place = {United States},
year = {Wed Jul 06 00:00:00 EDT 2016},
month = {Wed Jul 06 00:00:00 EDT 2016}
}