Instrument SCS

Spectroscopy & Coherent Scattering (SCS): Electronic and atomic structure and dynamics of nanosystems and of non-reproducible biological objects using soft X-rays

The SCS instrument aims at the investigation of electronic and atomic structure and dynamics of soft matter, biological structures, magnetic materials and structures. Scientific areas of application are material sciences, structural and cell biology, nanomaterials and dynamics of condensed matter.

Experiments utilize scattering of coherent X-rays and detection of the coherent diffraction pattern. In coherent diffraction imaging (CDI) experiments 2D and 3D structures of condensed-matter samples will be investigated with resolution reaching into the 10 nm regime. Resonant magnetic scattering will be of benefit to study ultrafast magnetic processes of nanostructured materials. Resonant inelastic scattering and emission spectroscopy will enable to investigation of electronic structures. And for large biological structures (large complexes, viruses, cells) the soft X-rays possess optimum parameters to determine 2D structure information. Using X-ray photon correlation spectroscopy (PCS) in addition the equilibrium and non-equilibrium dynamics of magnetic systems can be investigated.

 

Layout of instrument SCS

Photon shutter (400 m), beam-split-and-delay, apertures, intensity monitor, differential pumping, visible laser in, extreme focusing (430 m), sample chamber (431 m), area X-ray detector, intensity monitor, time domain monitor, spectrum monitor, wavefront monitor and beam stop (440 m)

European XFEL

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Reports

SCS Workshop 2009: Report of Working Group I on photon-in/photon-out and electron-out spectroscopic experiments

W. Wurth, University of Hamburg & CFEL; Z. Hussain, ALS (2.4 MB, en)

SCS Workshop 2009: Report of Working Group III on spin, charge and orbital dynamics in complex materials by resonant elastic scattering at the European XFEL

Jan Lüning, Université Pierre et Marie Curie, Paris; Gerhard Grübel, DESY (2.0 MB)

Other working group reports on soft X-ray instruments you find on the SQS page.

SCS Workshop 2009

The first SCS workshop took place in Villigen in June 2009. Visit the workshop page to get more information including the slides of the given presentations.

Mailing list

To subscribe to the mailing list of this experiment station, please use the form at information for the scientific community.

Instrument design

Initial design, TDR-2006 & startup configuration:

• The SCS instrument has been created by merging all originally proposed coherent scattering instruments for soft X-rays described in the TDR-2006. The driving idea was that scattering would be very similar, but varying requirements to sample manipulation and detection need to be evaluated.
• Mounting of samples typically requires a diffractometer to orient and manipulate samples.
• Coherent diffraction patterns need to be collected in forward direction and also near Bragg-diffraction spots using 2D detection systems.
• Photon correlation spectroscopy will use long distance (∼2 m) to the sample to increase the angular resolution (∼10 μrad).
• Experiments are sensitive to the size of the focal spot on the sample. For the CDI experiments the illuminated sample area contributes to the scattering and influences therefore the signal-to-background ratio. If the spot is much larger than the sample the signal-to-noise ratio decreases. In PCS experiment the size of the beam spot size or the sample feature (whatever is smaller) determines the typical speckle size at the detector.
• Experiments are likely to request X-ray flux adjustment to prevent sample damage.
• X-ray beam will be focused to focal spots of ∼100 nm, ∼1 μm and ∼10 μm.
• The wavefront of the focused X-ray pulse shall be flat or at least known.
• Usage of a monochromator (ΔE/E ∼ 10^-4) is requested in order to tailor the longitudinal correlation length and to select a small enough bandwidth to increase signal-to-noise in resonant scattering experiments.
• The X-ray beam requires pulse-by-pulse diagnostics of intensity, position, (spot size). Regular measurement of X-ray wavefront and pulse arrival is wishful. Part of this task might be achieved using a specially designed beam stop, other requires intersection of the beam.
• Due to absorption the entire beam path must be in vacuum. Special sample preparation methods are envisaged.
• Methods to visualize the sample (morphology, etc.) might provide insight into sample damage.
• Detection will be achieved by use of the newly developed 2D pixel detectors. In the moment the DEPFET detector with a pixel size of (200 μm)² is discussed for this instrument (still lacking confirmation). Detector distances need to be determined. The detector has a central hole for the direct beam. Number of pixels is 1 million.
• Construction of one X-ray hutch is foreseen for this instrument. In addition a control hutch will be built for operation of the instrument.

Beamline design considerations

• Instrument is located at SASE 3 beamline (designed for <∼500 eV up to 3 keV, providing horizontal linear polarization).
• Instrument is about 400 m from source point.
• Beamline will be designed for optimized transport of coherent X-ray beam.
• Beamline will feature a monochromator allowing a resolution of a few 10^-5 to a few 10^-4 thereby raising the longitudinal coherence length.