Welcome to Dubble XAFS beamline (BM26A)

X-ray Absorption Spectroscopy

X-ray Absorption Fine Structure Spectroscopy (XAFS) is a powerful technique to investigate the local atomic geometry and the chemical state of the atoms of one specific element in almost any type of substance. It is particularly well suited to investigate materials that lack long-range order like:

• nanomaterials, amorphous and highly disordered solids (clusters, catalysts, etc…)
• liquids, gels, molecular solutions, liquid crystals (molecular sieves, etc… )
• molecules and macromolecules containing metallic or heavy atoms (polymers, biomolecules, etc …)

Samples with very low concentration (min. 500 ppm) can be measured in Fluorescence mode.

Beamline characteristics

BM26A (see manual below) is designed to perform high quality XAFS measurements in a broad range of elements and samples.

Elements accessible on BM26 A

All chemical elements written with white fonts on coloured background can be studied at the Dubble XAFS station (see also the Note under the image). Among them, those already studied are underlined. To get the list of EXAFS/XANES publications corresponding to a given element, click on it in the image.

 
Note: To measure radioactive elements, you should come to an agreement with the ESRF Safety long before you apply for beamtime.

The main characteristics of the beamline are:

• Incident energy range with a reasonable flux from 4.9 to 32 keV
• Flux of 1 × 10¹¹ photons/sec
• Energy resolution dE/E of 2 × 10^-4
• Horizontal acceptance 2 mrad
• Beam size at sample place (H × V) max: 30 × 3 mm², min: 0 × 0.2 mm²
• Beam offset during a typical EXAFS scan varying from ca. 600 (Ti K-edge) to 10 μm (Sb K-edge)
• Step-by-step data collection with the reasonable acquisition time of 1s for optimised samples
• Quick EXAFS mode with time resolution of 3 minutes for fast EXAFS measurements

Detectors

BM26A beamline is equipped with:

• three low noise ion chambers Oxford Instruments for transmission experiments at high concentrations
• a 9-element monolithic Ge detector with a max. count rate per element ~150kHz and an energy resolution < 250 eV at 5.9 keV for fluorescence measurements at low concentrations
• a position sensitive INEL CPS 590 detector for combined WAXS / XAFS measurements
• a MarCCD 165 detector

Fluorescence detector	INEL detector

Software

The acquisition program used at BM26A, called Exafs, is described in the beamline manual. All the other tasks (sample positioning, beam alignment, ...) are done in SPEC. Signal processing is performed by the XSPRESS system developed at the Daresbury Laboratory.

A list of XAFS softwares for data analysis is provided here.

Manual

A beamline manual of BM26A is provided here. It gives all (or most of) the information a user may need to perform a successful experiment.

Sample environment

• Low temperature measurements down to 12 K using an Oxford CCC 1204 cryostat
• High temperature measurements up to 1000 °C. Gas blower to heat the samples inside a capillary can be borrowed from the technical beamline support group (TBS)
• Some cells for catalysis experiments are available
• High pressure gas system

In situ cell (1 atm - 450°C)	XANES of Cu catalyst reduction

Time resolved measurements with combined XAFS, WAXS, and SAXS techniques

The setup is able to probe the same part of the sample during the synthesis process with a time resolution in the order of several minutes. This combination has been successfully applied to probe the in situ crystallisation of molecular sieves. Example shown of in situ time resolved crystallisation of a CoAlPO₄ aluminophosphate gel measured from RT to 180 °C.

Combined XAFS, WAXS, SAXS set-up

Time resolved Quick EXAFS, WAXS and SAXS of the crystallization of CoAlPO-5 (from left to right)

References:

• Beale, A. M. et al. J. Am. Chem. Soc. 128, 12386 (2006).
• Grandjean, D. et al. J. Am. Chem. Soc. 127, 14554 (2005).
• O’Brien, M. G. et al. J. Am. Chem. Soc. 128, 11744 (2006).
• Van Santen, R. A., Nature 444, 46 (2006).
  

Click here to see more XAFS publications based on Dubble measurements.

If you want to know more about DUBBLE's XAFS station, please contact Sergey Nikitenko, Miguel Silveira (beamline scientists), or Wim Bras (project leader).

Literature

1. G. Derbyshire, K.-C. Cheung, P. Sangsingkeow and S. S. Hasnain, A low-profile monolithic multi-element Ge detector for X-ray fluorescence applications, Journal of Synchrotron Radiation 6 (1999), no. 2, 62-63.
2. R. Farrow, G. E. Derbyshire, B. R. Dobson, A. J. Dent, D. Bogg, J. Headspith, R. Lawton, M. Martini and K.Buxton, XSPRESS - X-Ray signal processing electronics for solid state detectors, Nuclear Instruments & Methods in Physics Research Section B-Beam Interactions with Materials and Atoms 97 (1995), 567-571.
3. G. A. Metselaar, E. Schwartz, R. de Gelder, M. C. Feiters, S. Nikitenko, G. Y. Smolentsev, G. E. Yalovega, A. V. Soldatov, J. J. L. M. Cornelissen, A. E. Rowan and R. J. M. Nolte, X-ray spectroscopic and diffraction study of the structure of the active species in the Ni^(II) catalyzed polymerization of isocyanides, ChemPhysChem 8 (2007), 1850-1856.
4. E. Sacaliuc, A. M. Beale, B. M. Weckhuysen and T. A. Nijhuis, Propene epoxidation over Au/Ti-SBA-15 catalysts, Journal of Catalysis 248 (2007), no. 2, 235-248.
5. E. J. M. Hensen, E. A. Pidko, N. Rane and R. A. van Santen, Water-promoted hydrocarbon activation catalyzed by binuclear Gallium sites in ZSM-5 zeolite, Angewandte Chemie International Edition 46 (2007), 7273-7276.
6. E. J. M. Hensen, Y. van der Meer, J. A. R. van Veen and J. W. Niemantsverdriet, Insight into the formation of the active phases in supported NiW hydrotreating catalysts, Applied Catalysis a-General 322 (2007), 16-32.
7. K. Kogej and B. Goderis, Association behavior and ordered nanoaggregation of charged fullerene derivatives and cationic surfactants in solution, Journal of Physical Chemistry C 111 (2007), no. 7, 2892-2900.

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