SAMBA

Optical layout

• Mirrors
• Sagittal focusing double crystal monochromator
• Quick-EXAFS monochromator (no longer available)

Mirrors

Two cylindrically bendable silicon mirrors (WinlightX) coated by a layer of 50 nm of Pd are used for providing:

1. vertical collimation of the beam
2. vertical focusing of the beam at the sample position
3. harmonic rejection.

The mirrors are used over the whole 4-40 keV energy range available on the beamline by tilting the mirrors from 10 mrad to 1 mrad (i.e. 0.57° to 0.057°) depending on the desired cut-off energy for removing the harmonic X-rays.

The reflective Pd surfaces are 1200 mm long per 88 mm wide allowing a horizontal acceptance of about 6.2 mrad on the first collimating mirror located at 14.1 m from the source. The surface of the mirrors was polished to a rms roughness less than 3 Ǻ rms and to a  longitudinal slope error less than 2µrad rms. The first mirror is water cooled using blades immersed in In-Ga eutectic in grooves in the mirror surface.

The focusing in the vertical direction is ensured by the M2 mirror, the resulting vertical spot size at the sample position is 110 µm (FWHM) with a foot size of about 300 µm.

Sagittal focusing double crystal monochromator

Sagittal focusing double crystal monochromator

The sagittally focusing Double Crystal Monochromator (DCM) provided by Oxford Danfysik is used in the so-called high flux mode. The DCM is installed at 16.1 m from the source. It deals of a first flat water-cooled Si(220) or Si(111) crystal and a sagittally bent 2nd crystal. The main Bragg axis of rotation passes through the centre of the diffracting face on the 1st crystal and perpendicular to the beam axis. In this way, the incident white beam is always centred on the axis of rotation. A fixed offset to the exit beam is achieved by moving the 2nd crystal perpendicularly to the first one according to the Bragg angle. In this case the beam moves along the axis of the sagittally-bent 2nd crystal. The first crystal is indirectly water-cooled by using a multi-channel water cooling support (SOLEIL original design) in contact with the crystal through a thin film of In-Ga eutectic. The 2nd crystal is uncooled.

The horizontal acceptance of the monochromator is limited by the efficiency of the sagittal bender. For a horizontal acceptance of 1.5 mrad, the typical beam size at the sample position is around 300 µm (H) x 200 µm (V) (FWHM).

In order to avoid possible radiation damage on the sample due to the high density of photons in a so small spot, the beamline is often slightly defocused in both directions to achieve a spot size of 2 mm (H) x 1mm (V).

Flux at the sample position provided by the Si(220) and Si(111)

 Flux at the sample position provided by the Si(220) and Si(111)

Normalized flux at the sample position for the Si(220) and Si(111) sagittally DCM (400 mA stored current, 1.5 mrad horizontal and 1 mrad of grazing incidence on the mirrors).

Then the typical flux at the sample position at 8.5 keV is 5 1011 ph/s with the Si(220) DCM and 1.2 10¹²ph/s with the Si(111) DCM (6 mrad of vertical acceptance and 1.5 mrad of horizontal acceptance, I = 400 mA).

Related publications: 

SAMBA: The 4-40 keV X-ray Absorption Spectroscopy Beamline at SOLEIL. 
V. Briois, E. Fonda, S. Belin, L. Barthe, C. La Fontaine, F. Langlois, M. Ribbens, F. Villain 
UVX 2010 - 10e Colloque sur les Sources Cohérentes et Incohérentes UV, VUV et X ; Applications et Développements Récents: 41-47. EDP Sciences 2011

Quick-EXAFS monochromator (no longer available)

The SOLEIL designed Quick-EXAFS monochromators are made of two independent channel-cut crystals (Si(111) and Si(311)). Each channel-cut crystal is mounted on a cam driven tilt table allowing it to oscillate periodically with amplitude θ(t) around an average fixed Bragg angle θB. The amplitude can be tune from 0.1 to 4° by an original SOLEIL in vacuum variable cam design. The θB Bragg angle is selected by one of the two goniometers holding the oscillating tilt tables. The 4 to 37 keV energy range is available using both Quick-EXAFS monochromators. The channel-cut crystal can be changed by the other one in few seconds during an experiment allowing to record quick-EXAFS data at absorption edges very far in energy. For instance the XAS study of a bimetallic catalyst at both edges during the same catalytic reaction is now possible with the SAMBA’s QuEXAFS set-up, even if the edge energies of those elements are covered by two distinct crystals.

Quick-exafs monochromator

Maximum performance of the Quick-EXAFS mechanics in terms of oscillation frequency of the channel-cut is 40 Hz for two recorded spectra: one with the Bragg angle collection in the downward direction and the other with the Bragg angle collection in the upward direction. Due to the photon flux available at the sample position at the SAMBA beamline in QuEXAFS configuration ((flux ~ 1011 ph/s at 8 keV) the optimal time resolution of experiments on real concentrated and not too absorbing samples is around 100 ms.

(left) Absorption of stacked Cr and Mn metallic foils measured over an amplitude of 3.6 °. Data are the average of 10 spectra each collected at 1Hz. (right) k2 weighted Quick-EXAFS are compared to standard scans taken in almost 15 min.

Related publications:

The SAMBA Quick-EXAFS monochromator: XAS with edge jumping 
E. Fonda, A. Rochet, M. Ribbens, S. Belin, L. Barthe, V. Briois 
Journal of Synchrotron Radiation (2012), 19, p 417 - 424 

Find in the following, the detection modes available on the EXAFS experiment, the different combination of techniques and some ancillary equipments.

• Sagittal Mode
• Quick-exafs Mode
• CombinedTechniques

• Catalysis
• Energy Science
• Low temperature
• Liquid Cells (for transmission and fluorescence)

Sagittal Mode

Crystal type : Si220 (4 to 42 keV)  Si111 (4 to 22 keV)
Beam size : 300μm x 200μm  /  75μm x 75μm using capillary

Detection

Transmission :

Oxford ionization chambers

Fluorescence :

 Canberra 35-elements  monolithic planar Ge pixel array detector

 Detector Silicon Drift : Vortex

Total electron yield

No picture. The sample must be electrical conductor otherwise a thin layer of graphite may be evaporated. 

Beam size using capillary : 75μm x 75μm

Application in Environmental science as an example, but also microfluidic application and grazing incidence of thin films. 

Quick-exafs Mode

Crystal type : Si311 Si111 (4 to 37 keV)
Beam size : typically 0.5 mm x 1 mm
Flux ~ 1011 ph/s at 8 keV

Detection

Transmission

Oken ionization chambers

Fluorescence

Avalanche Photo Diode (APD)

TEY

Tey absoption spectrum

Ni K edge XAS signal (up) collected in a TEY detection mode on a Proton Exchange Membrane Fuel Cell thick film in the Quick-EXAFS mode after correction of glitches. The presented spectrum is not averaged (5s of time acquisition).The frequency of oscillation of the Si(111) channel-cut was 0.1 Hz (5s per spectrum) with an oscillation amplitude of 1.6°.

No picture. The sample must be electrical conductor otherwise a thin layer of graphite may be evaporated. 

Edge Jump

Large energie range from 4 keV (Si111) to 37 keV (Si311) in 30s
The remote selection of the monochromator crystals, Si(111) or Si(311), allowing users to permanently access energies between 4 and 37 keV in Quick-exafs mode. 

The SAMBA quick-EXAFS monochromator: XAS with edge jumping

E. Fonda, A. Rochet, M. Ribbens, S. Belin, V. Briois The SAMBA quick-EXAFS monochromator: XAS with edge jumping J. Synchrotron Rad. 2012, 19, 417 – 424.

Example of the energy range accessible with Si111 cam=4°

Notice :

quick-exafs_anglais.pdf (1.4 MB - pdf) (1.4 MB)

Media Folder: 

SAMBA

CombinedTechniques

XAS with Raman spectroscopy

XAS with Raman spectroscopy

Kosi RXN1-785 Kaiser

Iexc. = 785 nm or 532 nm
CCD: 100-3450cm^-1 or 200-4000 cm^-1
Optical fibers 
with probehead
Seceral Long Working Distance objectives (150 mm to 35 mm)

XAS with UV-visible spectroscopy

Cary 50 VARIAN

With optical fibers
190 < I < 1100 nm
VScan < 24000 nm/min
XAS cell with mylar or PP windows for optical fiber used in transmission
or immersion probe : 2 or 10 mm
or cuvettes Quartz, Glass, PMMA, PS

XAS with Raman and UV-Visible spectroscopies

XAS with Differential Scanning Calorimeter (DSC)

DSC 111 Setaram :

Calvet type differential scanning calorimeter 
-120 to 800°C 

  * Phase transition (fusion, crystallization,
     glass transition, polymerization, degradation)
  *  Cp Evaluation
  *  Monitoring of reactions 
      (oxidation, reduction, dehydration...)

Catalysis

Retrouvez ci-dessous les différents environnements échantillons catalyseurs à votre disposition sur la station EXAFS.

Polyvalent SOLEIL development for fluorescence, transmission and Raman coupling

La Fontaine, C., Barthe, L., Rochet, A., & Briois, V. 
X-ray absorption spectroscopy and heterogeneous catalysis: Performances at the SOLEIL's SAMBA beamline.Catalysis Today, 2013, 205: 148–158

Characteristics   Lytle-type cell

• RT 600°C +/- 0.5°C
• Atmospheric pressure
• Powdered catalyst gently pressed into the cavity of the sample hoolder (thickness 2, 4 and 6 mm, 0.10 - 0.25 cm³)

High pressure cell for transmission and Raman coupling

A. Rochet et al. Catalysis Today (2011) vol 171 186-191 
A. Rochet et al. Diamond Light Source Proceedings (2011) 1, e130 1-4 

Characteristics  Lytle-type cell

• RT 600°C +/- 0.5°C
• 50 bar
• Powdered catalyst gently pressed into the cavity of the sample holder (thickness 2 mm)

Commercial cell Harrick for fluorescence and Raman coupling

C. La Fontaine et al. Harrick Scientific Products (Ed.), Application Note n°91201 (2010).

Characteristics

• RT 500°C
• Atmospheric pressure
• Powdered catalyst (≈50 mg) gently pressed into the sample holder cavity
• Catalyst pellet (6 mm dia.) disposed onto a BN bed

Gas distribution system

• Complex mixtures
• Saturator for liquid reactants
• Heated lines (120°C)
• Patm --> 20 bar
• Remote control

Mass spectrometer

MKS Cirrus
LM99 Analyser

• Tripple mass filter, 1-200amu or 1-300amu
• Faraday and SEM detector
• Maximum operating pressure Faraday 2x10-5 mBar

Energy Science

Setup for Li/Na batteries

VMP3 Bio-logic Multi-channel Potentiostat 

16 independent channels, 6 already equipped whose one for impedance measurement

Low temperature

Helium Cryostat

He cryostat suitable for transmission and fluorescence detection 
(20 K to Room Temperature)

Nitrogen Cryostat

Liquid nitrogen (80 K) cryostat suitable for transmission and fluorescence detection

Liquid Cells

We have different cells with fixed or variable optical path available for basic or acidic solution. Two of them are thermostatically controlled. Note Kapton, Mylar, PP or PTFE can be used as windows depending of the nature of the solution.

Liquid cell with variable optical path for transmission

Thermostated liquid cell (PTFE) with  adjustable optical paths (10 µm to 6 mm)  suitable for the combination of  transmission XAS with UV-Vis spectroscopies (design SPECA)

Liquid cell for transmission

Liquid cells PTFE with fixed optical paths
(0.5<o.p.<5mm)

Liquid cell for fluorescence mode

Liquid cell (PCTFE) for fluorescence detection
(design F. Villain)

Liquid cell for biological sample

PTFE sample-holder for He cryostat 
(two samples ~ 50µl) available for 
transmission and fluorescence detection 

Thermostated liquid cell

Thermostated liquid cell (PCTFE) with adjustable optical paths (100µm to 10mm) suitable for the combination of transmission XAS with Raman and/or UV-Vis spectroscopies
(design F. Villain)

Thermostated liquid cell (PTFE) with adjustable optical paths (10µm to 6mm) suitable for the combination of transmission XAS with UV-Vis spectroscopies (design SPECA)

Surface preparation and growing of thin films under UHV  (10-10)

Tools for preparation 
Knudsen cells, Source for
Omicron electron, Quartz balance

XAS detectors
Dinode (TEY), 7-elements Ge Canberra (fluorescence)

Surfaces caracterization
Auger, LEED, Quadrupole residual gas analyser

Note: The sample holder can be cooled down to -190°C and heated up to 1000°C (depending on the transferable holder type).

View of the UHV SEXAFS vessel:
(A) manipulator for transfer of samples;
(B) storage carrousel chamber;
(C) main analysis/growth chamber;
(D) 7 elements Ge detector (Canberra France)

Notices :

gnuplothowto.pdf (114.69 KB)

new_holderpositions.pdf (84.22 KB)

sputteringhowto.pdf (62.75 KB)

tbt_cryostats.pdf (54.91 KB)

augerhandbook.pdf (340.67 KB)