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Beamline: D4
X-Ray Reflectivity and Grazing Incidence Diffraction
This versatile, medium to high-resolution X-ray scattering instrument serves for diffraction and scattering investigations of solid-states to liquids particularly under grazing incidence and exit. With exception of reflectivity the scattering plane of the instrument is horizontal. Because all arms are equipped with air-pads moving on a 5m2 Tanzboden, heavy loads on the sample table, e.g., UHV chamber, cryostat or Langmuir troughs can be accomodated.
The UHV beam-pipe from the source to the mirror incorporates a water-cooled slit system (vertical and horizontal) and a single Be-window. 21 m from the tangent point of the bending magnet the white unfocused beam hits a gold coated mirror to cut off the high-energy part of the spectrum. It is placed in a separate box inlayed with lead to reduce the scattering background.
The monochromator vacuum chamber is located behind the mirror inside the experimental hutch. By tilting the monochromator (Δλ/λ = 2...5x104 for Ge(111) and Δλ/λ = 2% for W/C) the beam may be deflected 10 degrees downwards (not with W/C multilayer) which is ideally suited to the investigation of liquids.
A complete HUBER 10x10 cm2 goniometer head is mounted on the sample goniometer. Below this an elevator is able to move the sample into the centre of the beam. Mechanical construction at entrance and exit allow different devices (pneumatic absorber box, slits, flight-tubes, monitor counter, detectors) to be situated and positioned on a bench parallel to the beam.
Two NaI and a 50 mm (linear) position sensitive detector (PSD) are available. For the NaI there are holders for both direct view (detector) and perpendicular (monitor) view (Kapton foil). The PSD can only be used in direct view, however, the absorber box ensures that the intensity can be attenuated. To vary the resolution it is possible to change the detector-sample distance between 25 and 90 cm on the bench. In addition, for special applications an image plate can be mounted instead of the detector. It can be read out with a resolution down to 80µm.
The instrument is controlled via a VME crate using HASYLAB-SPECTRA which can run a RISOE-TASCOM emulation. The PSD system works separately on a PC triggered by TASCOM.
Applications
Organic films onto water as well as solid states materials and multilayers: Grazing incidence diffraction and X-ray reflectivity depth resolved surface and interface measurements. Powder diffraction at high temperature and pressure
Literature on Instrumentation
J. Als-Nielsen: "Solid and Liquid Surfaces Studied by Synchrotron X-Ray Diffraction", in Structure and Dynamics of Surfaces, Eds. W. Schommers, P. v. Blanckenhagen "Topics in Current Physics" 2, Springer, I986
Instrument Specification
|
Source |
bending magnet (Ec = 16.6 keV) |
|---|---|
|
Beamsize |
20 x 7 mm2 (h x v) max. |
|
Monochromator |
Ge (hhh) (flat, channel-cut: double, triple) |
|
Detector |
50 mm PSD, Image Plate, NaI |
|
Energy range |
5-20 kev (with mirror), 5-150 keV (without mirror) |
|
Energy resolution |
2...5x10-4 for Ge (111) and 2x10-2 for W/C |
|
Mirror |
flat, gold-coated, cut-off 8 - 20 keV |
|
Flux at 10 keV |
109(Ge(111)) - 1011 (W/C) photons/s/mm2 |
|
I(λ/3):I(λ): |
< 3 x 10-5 |
