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.
(Less)
- author
- 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.
- organization
- publishing date
- 2017-08-01
- 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
-
- pmid:28762964
- wos:000406756100003
- scopus:85026557508
- ISSN
- 2052-5206
- 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
- 2024-01-14 03:54:45
@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 = {{2052-5206}},
keywords = {{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}},
doi = {{10.1107/S2052520617006357}},
volume = {{73}},
year = {{2017}},
}