BL11 : experimental equipment

Overview of XAFS measurement system

  In experimental hutch No. 1, measurement equipment is installed for XAFS measurements, including detectors, stages and a slit. This equipment is installed on an experimental stage having dimensions of 1.2 m (long) × 1 m (wide). The beam height is 360 mm from the top of the experimental stage.

 

Schematic view of experimental stage for XAFS measurement system 

Fig. 1: Schematic view of experimental stage for XAFS measurement system.
 
<Detectors>
  • Ionization chambers
  • Lytle detector
  • Silicon drift detector
  • Conversion electron yield (CEY) detector

 

<Oprics>

θ stage with X-Z stage

Step θ stage: 0.0025º/pulse

   X stage: 0.001 mm/pulse (stroke: ±75 mm)

   Z stage: 0.0001 mm/pulse (stroke: ±50 mm)

 

 

<Experimental stage>

Size: 1.2 m (L) × 1 m (W)

 

 

<Slit with X-Z stage>

Slit stroke: ± 10 mm

X stage: 0.001 mm/pulse (stroke: ± 25 mm)

Z stage: 0.0001 mm/pulse (stroke: ± 10 mm)

 

 

<Measurement devices>

Power supply for NIM bin, high-voltage power supplies for ionization chambers, current amplifier, VF converter, quad counter, spectroscopic amplifier, SCA, MCA, etc.

 
 
Measurement system in transmission mode

Transmission mode is standard for XAFS measurement and it is performed using two ionization chambers. The energy range covered is from 3.5 to 23 keV. A suitable combination of ionization chambers and filling gases should be selected depending on the energy range of the experiment.  

 
Gas-flow ionization chamber

Gases: helium, nitrogen, argon, and mixtures of these gases

Lengths: 6.5 cm, 17 cm, 31 cm

Maximum voltage: 2000 V

 
Cu K-edge XAFS spectra of Cu foil measured in transmission mode at room temperature 

Fig. 2 Cu K-edge XAFS spectra of Cu foil measured in transmission mode at room temperature.

 
 
Lytle detector for fluorescence mode XAFS

 The Lytle detector, which is an ionization chamber with a large detection area, is used for fluorescence XAFS.

 

Energy range

3.5 ~ 23 keV

Sample conditions

Concentration of dilute sample > 0.1 wt.%

Thickness of thin film sample > 100 nm

 
View of Lytle detector 

Photo 1: View of Lytle detector

 
Silicon drift detector for fluorescence mode XAFS

 The silicon drift detector is used for fluorescence XAFS for dilute or thin film samples that require a high energy resolution to resolve the fluorescence signal from the target material.

 
Detectable size

50 mm2 × 2 mm (t)

Energy range

3.5~23 keV

Sample condition

Concentration of dilute sample > 100 ppm

Thickness of thin film sample > 10 nm

View of silicon drift detector 

Photo 2: View of silicon drift detector

 
Measurement system in conversion electron yield (CEY) mode

The CEY detector is mainly used for thin film samples that have high concentrations of atoms. CEY mode has the advantage that it detects signals with a higher efficiency than fluorescence mode.

 
Sample stage size

Diameter: 50 mm

Energy range

3.5 ~ 23 keV

Sample condition

Thickness of thin film sample > 0.5 nm and other kinds of samples 

 
View of CEY detector 

Photo 3: View of CEY detector

Kyushu Synchrotron Light Research Center
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