The EH2 station of the ID10 beamline is optimized for scattering experiments with coherent X-rays. X-ray photon correlation spectroscopy and coherent diffraction imaging are the main techniques used. Scientific applications cover studies of the structural and dynamic properties of soft and hard condensed matter materials (see also the  EH2 science page).

The main features of the beamline are:

EH2-CS:

  • High-resolution instrumentation for horizontal scattering geometries (SAXS to WAXS)
  • Possibility of grazing incidence scattering from liquid surfaces
  • Large energy-tunability (7 keV < E < 24 keV)
  • Water cooled Silicon (111) crystal pseudo channel cut monochromators
    (intrinsic energy resolution ΔE/E : 1.4*10-4)
  • High coherent flux (7 keV = 1010 ph/sec/100mA; 8.1 keV =4*1010 ph/sec/100mA; 21 keV = 1010 ph/sec/100mA  in a 10x10 µm2 beamspot, ΔE/E = 1.4*10-4)
  • Specialized in scattering techniques using a coherent X-ray beam
  • Optimized for X-ray photon correlation spectroscopy (XPCS) (7-10 keV, 21-24 keV) and coherent X-ray diffraction imaging (CXDI) (7-10 keV)
  • "Pink" beam option (ΔE/E = 1-3%) (available from January 2013)

Scientific Applications

X-ray photon correlation spectrsocopy (XPCS) is a technique based on quantifying the temporal correlations in a fluctuating speckle pattern produced in the far-field by a coherent X-ray beam. XPCS allows the study of slow in-equilibrium and out-of-equilibrium dynamics in disordered or modulated materials on timescales beyond the reach of the inelastic (X-ray or neutron) techniques. XPCS is complementary to dynamic light scattering (DLS) and typically covers a time window of 10-8 s < t < 1000 s. The combination of small-angle (SAXS) and wide-angle (WAXS) scattering allows to cover length scales from several thousand Angstroms (Q ~ 10-3 Å-1) down to atomic resolution (Q ~ 1 Å-1). Examples of applications are:

  • Dynamics in colloidal and polymer systems
  • Domain-formation and dynamics in phase separating systems
  • Dynamics in glass forming systems
  • Dynamics in structural glasses
  • Critical dynamics
  • Surface, capillary wave and membrane dynamics

CXDI is a lens-less imaging method where the electron density distribution in real space is obtained by phasing an oversampled speckle pattern in reciprocal space recorded in the far field via an iterative phase retrieval algorithm.  Imaging of non-crystalline 3 micron objects can ROUTINELY be performed at 18 nm resolution in 3D at 8KeV.
The target of CXDI is high resolution imaging of:

  • Biomineral hierarchical structures
  • Porous semiconductor materials
  • Mineral nanocrystals and nano-structures
  • Biological cells

Available techniques

EH2 is equipped with an incidence flight path, a 4-circle horizontal diffractometer, an optical table on air cushions carrying the detectors that can be translated to vary the sample-to-detector distance from 2m to 7m for SAXS geometry. The incidence flight path has Si filters, a fast ms shutter, local tilting mirrors for GI techniques and roller-blades slits defining the coherent beam. The versatile 4 circle diffractometer with variable resolution set-up on the detector side (slits and crystal analysers) together with the wide energy tunability and variable energy resolution permits virtually every diffraction experiment in horizontal scattering geometry. The detector optical table support evacuated flight path of several length that can be equipped with beam-stops in vacuum at the exit window.  The long distance available for the detector allows to reach in SAXS geometry a q min : 3e-4 Å-1.

A separate removable apparatus with a high resolution goniometer head with an air-bearing fast rotation and an on-line microscope is available for 3D-CXDI.

All available detectors are photon counting devices:

  0-D: Scintillators (dead-time: 0.3 µs), Avalanche Photo Diodes (dead-time: 7 ns )
  2-D: 256 x 256 Medipix 1x1 pixel detector (500 µm Si chip, 55 µm pixel size, image rate up to 1Khz)
          512 x 512 Maxipix 2x2 pixel detector (500 µm Si chip, 55 µm pixel size, image rate up to 300 Hz)
          1024 x 1024 Direct-Illumination CCD Andor cameras (500 µm Si chip, 13 µm pixel size, image rate up to 1 Hz)

X-ray Photon Correlation Spectroscopy (XPCS)

XPCS can be performed in the geometries:
- SAXS (7-10 keV, 21-24 keV), Q min: 10-3 Å-1. Standard SAXS profile can be taken with either a 0-D detector or a 2-D detector. The setup is optimized for dynamic XPCS experiments employing a coherent X-ray beam and not for high through-put SAXS data acquisition.
- WAXS (7-10 keV), Q max: 3 Å-1
- Bragg (7-10 keV), Q max: 3 Å-1
- Grazing incidence (7-10 keV)

The Time-correlation functions can be recorded with help of a digital autocorrelator (0D) or by a in-house multi-tau software correlator (2D).

Coherent X-ray Diffraction Imaging (CXDI)

The high resolution goniometer with on-axis microscope is used for samples in air on with samples on Si3N4 membranes. The setup  is compatible with a cryo-stream for cryo protection of frozen hydrated biological samples.  Up to 7 meters sample to detector distance allows measuring oversampled far-field diffraction patterns from up to 7 microns big object with the Maxipix 2x2 pixel detector. 3D reconstructions can be retrieved almost "on-line" by an in-house software.

Sample environments

Temperature controlled SAXS chambers are available for samples in glass-capillaries or flat containers. The "standard" SAXS chamber for sample in capillaries can be used from -20C  to 100C. A special low-temperature chamber using a cold N2-gas flow is avalable for temperatures down to 100 K for SAXS and GI geometries.

A furnace with a Eurotherm temperature control is available for samples in the form of foils or thin plates for XPCS in WAXS geometry. The maximum temperature is 700C.

Complementary Information