### Polycapillary based µ-XAS and confocal µ-XANES at a bending magnet source of the ESRF

Geert Silversmit UGent, Bart Vekemans UGent and Laszlo Vincze UGent (2009) p.30-30
abstract
Glass polycapillary optics are shown to be easy to use alternative focusing optics for bending magnet XAS stations, compared to e.g. Kirkpatrick-Baez mirror systems. Their acceptance is several mm horizontally and vertically, while the angular acceptance can be matched to the source divergence by the design of the polycapillary. Polycapillaries consist of a bundle of hundreds of thousand of small bent glass fibres all oriented towards the same focal point. Due to repeated total reflections the incoming X-rays are guided towards that focal point, resulting in an achromatic optic. A polycapillary half-lens based focusing system was successfully tested for transmission and fluorescence μ-XAS at DUBBLE (BM26A, ESRF). This beamline is equipped with a non-fixed exit Si(111) monochromator, the resulting vertical positional variations of the X-ray beam during an EXAFS scan are essentially cancelled by the focusing effect of the polycapillary. Beam sizes of 10-20 μm, transmission efficiencies of 25-45% and intensity gain factors of about 2000 were obtained in the 7-14 keV energy range. Although the polycapillary optic has a smoothly changing energy dependent transmission efficiency, the amplitude and shape of the EXAFS oscillations are not influenced by this. An EXAFS spectrum on a probed mass of 3 pg of Zn was achieved on a biological sample in fluorescence mode. In addition, by mounting a second polycapillary half-lens in front of an energy dispersive detector, a confocal set-up is obtained, which restricts the part of the sample seen by the detector to a microscopic volume of about 15x20x20 μm3 at the Fe K absorption edge. The applicability of the polycapillary μ-XAS set-up and the confocal μ-XANES is illustrated within the field of environmental science and geology.
author
organization
alternative title
Polycapillary based mu-XAS and confocal mu-XANES at a bending magnet source of the ESRF
year
type
conference
publication status
published
subject
keyword
µ-EXAFS, confocal µ-XANES, polycapillary
in
X-Ray Absorption Fine Structure, 14th International conference, Program and abstracts book
pages
30 - 30
conference name
14th International conference on X-Ray Absorption Fine Structure (XAFS14)
conference location
Camerino, Italy
conference start
2009-07-26
conference end
2009-07-31
language
English
UGent publication?
yes
classification
C3
id
967441
handle
http://hdl.handle.net/1854/LU-967441
date created
2010-06-01 13:32:35
date last changed
2016-12-19 15:36:25
@inproceedings{967441,
abstract     = {Glass polycapillary optics are shown to be easy to use alternative focusing optics for bending magnet XAS stations, compared to e.g. Kirkpatrick-Baez mirror systems. Their acceptance is several mm horizontally and vertically, while the angular acceptance can be matched to the source divergence by the design of the polycapillary. Polycapillaries consist of a bundle of hundreds of thousand of small bent glass fibres all oriented towards the same focal point. Due to repeated total reflections the incoming X-rays are guided towards that focal point, resulting in an achromatic optic.
A polycapillary half-lens based focusing system was successfully tested for transmission and fluorescence \ensuremath{\mu}-XAS at DUBBLE (BM26A, ESRF). This beamline is equipped with a non-fixed exit Si(111) monochromator, the resulting vertical positional variations of the X-ray beam during an EXAFS scan are essentially cancelled by the focusing effect of the polycapillary. Beam sizes of 10-20 \ensuremath{\mu}m, transmission efficiencies of 25-45\% and intensity gain factors of about 2000 were obtained in the 7-14 keV energy range. Although the polycapillary optic has a smoothly changing energy dependent transmission efficiency, the amplitude and shape of the EXAFS oscillations are not influenced by this. An EXAFS spectrum on a probed mass of 3 pg of Zn was achieved on a biological sample in fluorescence mode.
In addition, by mounting a second polycapillary half-lens in front of an energy dispersive detector, a confocal set-up is obtained, which restricts the part of the sample seen by the detector to a microscopic volume of about 15x20x20 \ensuremath{\mu}m3 at the Fe K absorption edge. The applicability of the polycapillary \ensuremath{\mu}-XAS set-up and the confocal \ensuremath{\mu}-XANES is illustrated within the field of environmental science and geology.},
author       = {Silversmit, Geert and Vekemans, Bart and Nikitenko, Sergey and Bras, Wim and Brenker, Frank E. and Vincze, Laszlo},
booktitle    = {X-Ray Absorption Fine Structure, 14th International conference, Program and abstracts book},
keyword      = {{\textmu}-EXAFS,confocal {\textmu}-XANES,polycapillary},
language     = {eng},
location     = {Camerino, Italy},
pages        = {30--30},
title        = {Polycapillary based {\textmu}-XAS and confocal {\textmu}-XANES at a bending magnet source of the ESRF},
year         = {2009},
}


Chicago
Silversmit, Geert, Bart Vekemans, Sergey Nikitenko, Wim Bras, Frank E. Brenker, and Laszlo Vincze. 2009. “Polycapillary Based µ-XAS and Confocal µ-XANES at a Bending Magnet Source of the ESRF.” In X-Ray Absorption Fine Structure, 14th International Conference, Program and Abstracts Book, 30–30.
APA
Silversmit, G., Vekemans, B., Nikitenko, S., Bras, W., Brenker, F. E., & Vincze, L. (2009). Polycapillary based µ-XAS and confocal µ-XANES at a bending magnet source of the ESRF. X-Ray Absorption Fine Structure, 14th International conference, Program and abstracts book (pp. 30–30). Presented at the 14th International conference on X-Ray Absorption Fine Structure (XAFS14).
Vancouver
1.
Silversmit G, Vekemans B, Nikitenko S, Bras W, Brenker FE, Vincze L. Polycapillary based µ-XAS and confocal µ-XANES at a bending magnet source of the ESRF. X-Ray Absorption Fine Structure, 14th International conference, Program and abstracts book. 2009. p. 30–30.
MLA
Silversmit, Geert, Bart Vekemans, Sergey Nikitenko, et al. “Polycapillary Based µ-XAS and Confocal µ-XANES at a Bending Magnet Source of the ESRF.” X-Ray Absorption Fine Structure, 14th International Conference, Program and Abstracts Book. 2009. 30–30. Print.