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SUL-X Beamline

The X-ray beamline of the Sychrotron Laboratory for Environmental Studies (Synchrotron Umwelt-Labor) combines diffraction, absorption and fluorescence measurements on environmentally relevant materials with microfocusing capabilities.

Sources of pollution, path of contaminants, and the contribution of synchrotron radiation based techniques via Molecular Environmental Science (MES) to enviornmnetal questions are the main tasks of this beamline.
Umwelt

 

 

The SUL X beamline is major part of the Synchrotron Laboratory for Environmental Studies supported by the German governments (BMBF and state Baden Württemberg) for dealing environmental questions with synchrotron radiation methods. Therefore this beamline is designed for combined measurements with a microfocusing capability.

Initially utilising a wiggler source the beamline will be upgraded at a later date with a superconducting undulator.

Environmental samples are generally complex (e.g., contaminated soils, mining dump sediments), consisting of mixtures of mineral phases (amorphous, crystalline, with micrometer or nano-scale particle sizes), microbes, and in some cases vegetable material. Spatial distribution, speciation, and phase association of trace levels of contaminants are the basis for risk assessment and development of remediation strategies (e.g. arsenic speciation and distribution in groundwater related sediments). This problem is best addressed by synchrotron based techniques capable of providing spatial resolution in the micrometer range while allowing the combination of microfocused techniques (XRF, XAS, XRD, IR), as foreseen in the SUL concept.

Layout

SUL-X

Schematic Beamline Layout

      

Optic components

 Bilder-SULX-webpage-Optik-M1  Bilder-SULX-webpage-Optik-M2uDCM  Bilder-SULX-webpage-Optik-KBM
Front-End with first, horizontal, focusing mirror (M1) First part of the otic hutchwith double crystal monochromator (DCM) and second, vertical, focusing mirror (M2)

End of the optic in experiemntal hutch with the Kirckpatrick -Baez mirror system (KBM)

xperimental station - 3D model (under construction)

 
 Messplatz


SUL-X21


Experimental station - Detectors

 
   Detector  Type  Main specification
 D1  Fluorescence 7 element Si(Li) (Gresham, now e2v)

Resolution (averaged over all elements, optimum peaking time):
<140 eV (at 5.9 keV, 1000 cps)
<310 eV (at 5.9 keV, 100.000 cps)

Area per element 30 mm2

 D2  Absorption 3 ionisation chamber (Oxford Instruments, IC-Plus type)  Active lenght 5cm, Kapton windows 6 µm thick
 D3  Diffraction CCD detector (Photonic science)

Active area 80x120mm2 (hor. x vert.)

Fiber optic 3.46:1 scaling down pixels 2048x2048, 16 bit dynamic through fusion mode

Readout time 3.3s – 21s
Vacuum compatible

 D4  Selection of sample spots Optical microscope (TSO Spezialoptik)

Resolution 2µm,

Transmitted and reflected light, Vacuum compatible



Experimental station - Sample stage

   Movement  Range
 S1  z stage  105 mm
 S2  x/y stage  100mm / 40mm
 S3  phi circle  360°
 S4  chi cradle  10°
 S5  theta circle 360°
 S6  2 theta circle   -160° to +15°

 

 

 

 

 

 

 

 

 

 

 

7 Element Si(Li) fluorescence detector (Gresham)

detectorintestdetector  

 

In-vacuum CCD detector (Photonic Science)

139_3948cc
CCD-Detector-SeitenansichtAnschluesse-139_3950cc
 

 

Methods

Available Methods, Obtainable Parameters

The SUL X-ray beamline closes the spectral gap between soft and hard X-ray spectroscopy, and offers to investigate samples - without remounting them - sequentially
with the following methods and modes:

Fluorescence Spectroscopy:

  •     elemental mapping of an extended sample :e.g. thin section of a contaminated soil sample
        (microfocused beam size mode)
  •     high sensitivity to low concentrations (primary “white light” beam with its high flux mode)


Absorption spectroscopy for all elements between S(Al) and U:

  •     information about the local atomic geometry (EXAFS)
  •     chemical state of the absorbing atom (XANES)
  •     investigations on ordered (crystalline) and disordered (amorphous, liquid) materials
  •     dilute species and light elements (fluorescence mode of XAS)


Diffraction experiments (powder and aggregates of crystals):

  •     location of pollutant atoms within a crystalline mineral matrix
  •     investigation of sample concentrations, chemical states of elements and their associations
        mineral phases
        down to the μm scale
  •     essential key parameters for environmental and health risk assessment

Advantages

  •     Nondestructive, Surface / volume sensitive
  •     Three X-ray techniques with microfocus without sample remounting
  •     Spectroscopy from light elements S(Al) to U at a single beamline


Purpose, summarized

  •     Environmental science, material science, biology
  •     Focus on inhomogeneous, complex samples
  •     Spatial element distribution, speciation, and mineral phase determination

 

Key parameters of the beamline

 

Energy range

2.3 kev - 19 keV (S K-edge, U L3-edge), later 1.4 keV (Al K-edge)

Energy resolution (DE/E)

Si(111) 2x10-4; Si(311) 1x10-4; YB66(004) 5x10-4;

 

(theoretical values) 

Source

Wiggler (27 pole each 74 mm), later upgrade undulator (100 pole each 14mm)

Optics (sorted in beam direction)

Toroidal mirror, horizontally focusing, vertically collimating

DCM with Si(111), Si(311), YB66(400) and mirror (white light)

Cylindrical mirror with three coatings, low energy band path, vertically focusing

Precise slit in focus, defining a “new” source with adjustable size

Elliptical Kirkpatrick Baez mirror system, focusing “new” source

Monochromatic or “white light” beam path, selectable.

Beam size at sample position

1 mm (hor) x 1mm (vert) down to 30 µm x 25 µm

(later down to 10 µm x 10 µm)

Flux at sample position

4 x 1010 (5keV), 3 x 1010 (10kev), 3 x 1010 (20keV) ph/s / 100mA e- current in spot size (FWHM) 0.2 mm (hor) x 0.1 mm2

Experimental station

 

Sample diffractometer with theta, phi circle and chi cradle (10°), xyz linear stages

CCD detector on 2theta arm for diffraction

3 retractable ionization chambers for absorption

7 element Si(Li) fluorescence detector for fluorescence

Optical microscope

Diffractometer and detectors all in vacuum vessel

Sample environment

Chambers for different environments (gases, liquids, T-controlled) are planned; low temperature environment down to -5 °C (small samples, peltier cooled), and down to -20 °C (flat samples, N 2 cryostream) available.