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Accurate charge densities from powder X-ray diffraction - A new version of the Aarhus vacuum imaging-plate diffractometer

Tolborg, Kasper; Jørgensen, Mads R.V. LU ; Christensen, Sebastian; Kasai, Hidetaka; Becker, Jacob; Walter, Peter; Dippel, Ann Christin; Als-Nielsen, Jens and Iversen, Bo B. (2017) In Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials 73(4). p.521-530
Abstract

In recent years powder X-ray diffraction has proven to be a valuable alternative to single-crystal X-ray diffraction for determining electron-density distributions in high-symmetry inorganic materials, including subtle deformation in the core electron density. This was made possible by performing diffraction measurements in vacuum using high-energy X-rays at a synchrotron-radiation facility. Here we present a new version of our custom-built in-vacuum powder diffractometer with the sample-to-detector distance increased by a factor of four. In practice this is found to give a reduction in instrumental peak broadening by approximately a factor of three and a large improvement in signal-to-background ratio compared to the previous... (More)

In recent years powder X-ray diffraction has proven to be a valuable alternative to single-crystal X-ray diffraction for determining electron-density distributions in high-symmetry inorganic materials, including subtle deformation in the core electron density. This was made possible by performing diffraction measurements in vacuum using high-energy X-rays at a synchrotron-radiation facility. Here we present a new version of our custom-built in-vacuum powder diffractometer with the sample-to-detector distance increased by a factor of four. In practice this is found to give a reduction in instrumental peak broadening by approximately a factor of three and a large improvement in signal-to-background ratio compared to the previous instrument. Structure factors of silicon at room temperature are extracted using a combined multipole-Rietveld procedure and compared with ab initio calculations and the results from the previous diffractometer. Despite some remaining issues regarding peak asymmetry, the new diffractometer yields structure factors of comparable accuracy to the previous diffractometer at low angles and improved accuracy at high angles. The high quality of the structure factors is further assessed by modelling of core electron deformation with results in good agreement with previous investigations.The present state of X-ray electron-density determination from powder-diffraction data is briefly reviewed together with the first results from a new large-diameter in-vacuum diffractometer.

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Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
core electron deformation, electron density, powder diffraction, vacuum measurements
in
Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials
volume
73
issue
4
pages
10 pages
publisher
Wiley-Blackwell
external identifiers
  • scopus:85026557508
  • wos:000406756100003
ISSN
2052-5192
DOI
10.1107/S2052520617006357
language
English
LU publication?
yes
id
56b4034f-3538-4f63-b3b1-392a72dde12b
date added to LUP
2017-08-31 09:33:13
date last changed
2018-01-07 12:16:45
@article{56b4034f-3538-4f63-b3b1-392a72dde12b,
  abstract     = {<p>In recent years powder X-ray diffraction has proven to be a valuable alternative to single-crystal X-ray diffraction for determining electron-density distributions in high-symmetry inorganic materials, including subtle deformation in the core electron density. This was made possible by performing diffraction measurements in vacuum using high-energy X-rays at a synchrotron-radiation facility. Here we present a new version of our custom-built in-vacuum powder diffractometer with the sample-to-detector distance increased by a factor of four. In practice this is found to give a reduction in instrumental peak broadening by approximately a factor of three and a large improvement in signal-to-background ratio compared to the previous instrument. Structure factors of silicon at room temperature are extracted using a combined multipole-Rietveld procedure and compared with ab initio calculations and the results from the previous diffractometer. Despite some remaining issues regarding peak asymmetry, the new diffractometer yields structure factors of comparable accuracy to the previous diffractometer at low angles and improved accuracy at high angles. The high quality of the structure factors is further assessed by modelling of core electron deformation with results in good agreement with previous investigations.The present state of X-ray electron-density determination from powder-diffraction data is briefly reviewed together with the first results from a new large-diameter in-vacuum diffractometer.</p>},
  author       = {Tolborg, Kasper and Jørgensen, Mads R.V. and Christensen, Sebastian and Kasai, Hidetaka and Becker, Jacob and Walter, Peter and Dippel, Ann Christin and Als-Nielsen, Jens and Iversen, Bo B.},
  issn         = {2052-5192},
  keyword      = {core electron deformation,electron density,powder diffraction,vacuum measurements},
  language     = {eng},
  month        = {08},
  number       = {4},
  pages        = {521--530},
  publisher    = {Wiley-Blackwell},
  series       = {Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials},
  title        = {Accurate charge densities from powder X-ray diffraction - A new version of the Aarhus vacuum imaging-plate diffractometer},
  url          = {http://dx.doi.org/10.1107/S2052520617006357},
  volume       = {73},
  year         = {2017},
}