Synopsis

BM23 is a multi-purpose EXAFS beamline optimized for high-quality EXAFS measurements in 4.5–90 keV range (or 4.5–45 keV with focused beam), in transmission or fluorescence mode. The beamline is equipped with a modern fixed-exit monochromator developed at the ESRF, resulting in sub-micron stability of the beam and measurement times down to a few seconds per EXAFS. BM23 offers a wide range of sample environments: catalytic reactors, infrastructure for reactive gases, mass-spectrometer for gas analysis, electrochemical equipment, cryostats, equipment for high-pressure studies with diamond anvil cells. A Pilatus 1M detector is available for quasi-simultaneous XAS/XRD experiments. Simultaneous XAS and DRIFTS measurements under controlled temperature and gas flow can be performed with the dedicated DRIFTS/XAS/MS setup. A microXAS station for focusing the beam below 3x3 μm FWHM is also available for space-resolved XAS and XRF studies.

Disciplines

• Chemistry
• Physics
• Earth and Planetary Sciences
• Materials and Engineering
• Environmental Sciences
• Cultural Heritage
• Life Sciences

Applications

• Catalysis
• Electrochemistry
• Solid state physics
• Earth and planetary science
• Materials science
• Environmental science
• Cultural and natural heritage
• Life sciences

Techniques

• XAS - X-ray Absorption Spectroscopy
• EXAFS - Extended X-ray Absorption Fine Structure
• XANES - X-ray Absorption Near Edge Structure
• XRD - X-ray Diffraction
• XRF - X-ray Fluorescence Spectroscopy
• TFY-XAS - Total Fluorescence Yield X-ray Absorption Spectroscopy
• PFY-XAS - Partial Fluorescence Yield X-ray Absorption Spectroscopy
• FTIR - Fourier Transform Infrared Spectroscopy

Sample environments

• CHEMISTRY
  
  Chemical reactors:
  Different reactors for in situ and operando studies under controlled temperature, pressure and gas feed. The samples can be measured as pellets, powder in capillaries, loose powder, deposited on support (depending on the experimental needs).
  DRIFTS/XAS/MS setup with dedicated catalytic reactor for simultaneous DRIFTS and XAS measurement at controlled temperature and gas flow.
  
  Gases:
  Gas delivery system: 11 gas lines for inert and reactive gases, including 3 gas cabinets for flammables and CO. Max pressure 20 bar.
  Two remotely controlled gas mixing setups for reactive gases:
  Low pressure (up to 4 bar) - 10 MFCs for 10-150 ml/min flow, electric 3-way valves, possibility to interface liquid saturator. Full remote control.
  High pressure (up to 18 bar) or fast switches - 4 MFCs for 20-50 ml/min flow, 4-way valve for fast switches, 2 back-pressure regulators.
  Higher pressure experiments are possible on-demand with dedicated pressure regulators and ad hoc setups (to be discussed in advance).
  
  Electrochemistry:
  Potentiostat Biologic SP150e
  Electrochemistry cell: coming soon
  
  Analytics:
  Mass-spectrometer for gas composition analysis Pfeiffer GSD 350
  IR gas analyzer
  UV-Vis spectrometer with fiber optics for transmission measurements
  
  
• EXTREME CONDITIONS
  
  Diamond anvil cells (DAC) (up to multi-Mbar pressures 400 GPa)
  Resistive heated DAC (1500 K, 100 GPa)
  High-pressure cryostat (5 K, 100 GPa)
  Paris-Edinburgh Press
  
  
• MATERIALS SCIENCE
  
  Liquid He cryostat (4-300K): for solids and liquids
  Online microscope setup for microXAS and microXRF measurements with focused beam
  Multi-sample holders: up to 52 samples stacked for high-throughput measurement (both solids and liquids).
  Anaerobic chamber for measurements of air-sensitive samples.
  Robot arm for very large sets of samples (>500)

Detectors

• XAS and XRF
  
  Gas-filled Ionization chambers for transmission measurements
  Si diode for total fluorescence yield measurements
  16-element Si-drift detector for partial fluorescence yield measurements (Ardesia)
  1-element Si-drift detectors with 1 and 2mm sensor thickness (Hitachi Vortex), compatible with polycapillary lens
  1-element Ge-drift detector - shared with ID15a
  FalconX electronics (16 channels)
  
  
• XRD
  
  Pilatus 1M XRD detector. Can be used quasi-simultaneously with XAS detectors for cobmined XAS/XRD experiments
  
  
• CHEMICAL ANALYTICS
  
  Mass spectrometer: Pfeiffer OmniStar GSD 350
  FTIR spectrometer: Agilent Cary 680 with optics and dedicated reactor for combined DRIFTS/XAS/MS measurements at controlled temperature and gas flow.
  Potentiostat Biologic SP-150e for electrochemical experiments: 2 channels, 1 A max current, EIS option
  FTIR gas analyser MATRIX-MG5 - shared with ID26
  
  
• RAMAN
  
  A PRL system for online pressure determination in the DAC

Technical details

Source

Bending magnet and 0.85 T 2-pole Wiggler

Monochromator

Fixed-exit ESRF monochromator. Si (111) for  4 - 50 keV, Si (311 ) for 7 - 90 keV

Mirrors

A pair of flat parallel mirrors with Si, Pt and Rh stripes. Incidence angle 2-5 mrad.

Focusing

3 x 3 µm (FWHM) using a pair of Pt coated mirrors in KB geometry

Both focused and unfocused operation is possible

Flux

6x10¹⁰ ph/s : Si (111), 21 keV,  200 mA mode, unfocused

6x10⁹ ph/s : Si (111), 21 keV, 200 mA mode, focused with KB mirrors at 3 mrad

Time resolution

Down to 1s for a single EXAFS scan (ΔE = 1 keV, continuous mode)

Down to 3 s/scan for consecutive EXAFS scans (ΔE = 1 keV, continuous mode)

Fast XRF mapping, down to 5 ms/point (continuous mode)

Energy Resolution

Si(311)  ca. 3 x 10^-5

Si(111)  ca. 1.5 x 10^-4

Stability

Energy stability during energy scans : few meV 

X-ray beam position stability during energy scans: 1 micron

REFERENCE PUBLICATION(s)

General publication:

O. Mathon et al., A. Beteva, J. Borrel, D. Bugnazet, S. Gatla, R. Hino, I. Kantor, T. Mairs, M. Munoz, S. Pasternak, F. Perrin, S. Pascarelli, J. Synchrot. Radiat. 2015, 22, 1548.

For extreme condition setups:

A.D. Rosa, G. Garbarino, J.E. Rodrigues, E. Mijit, ..., K.A. Lomachenko, O Mathon (2024) New opportunities for high pressure X-ray absorption spectroscopy at ID24-DCM and BM23 with the Extremely Brilliant Source of the ESRF High Pressure Research 44 (3), 248-276 https://doi.org/10.1080/08957959.2024.2364281