Single Crystal X-ray Diffraction (SCXD)

KNMF Laboratory for Microscopy and Spectroscopy

Single crystal X-ray diffraction is a method of determining the arrangement of atoms within a crystal, in which a beam of X-rays strikes a crystal and causes the beam of light to spread into many specific directions. From the angles and intensities of these diffracted beams, a crystallographer can produce a three-dimensional picture of the density of electrons within the crystal. From this electron density, the mean positions of the atoms in the crystal can be determined, as well as their chemical bonds, their disorder and various other information.

The data will be measured with a new STOE StadiVari goniometer which is equipped with an ultra-fast and sensitive DECTRIS PILATUS pixel detector (300 K) and two microfoci X-ray sources (Cu- and Mo-radiation). The special characteristics of the detector (ultrafast readout and almost zero background) in combination with high power X-ray sources offer new dimensions in time and data quality especially in the field of molecule crystallography. The attached low temperature device allows for measurements of the crystals from 120 to 350 K in a stream of nitrogen. Required size of the single crystals: between 0.02 and 0.2 mm. The smallest dimension of the crystal should not go below 0.02 mm.

In addition, we offer the possibility to measure micro X-ray fluorescence (m-XRF) with the Horiba XGT-9000. Due to a similar atomic form factor of neighbouring elements, distinguishing between these is impossible. In case of a crystallographic disorder the analysis is even more difficult. Exact refinement of the structure is almost impossible without further analysis methods.

m-XRF offers the possibility of a (semi-)quantitative elemental analysis. The Horiba XGT-9000 is designed to analyze single crystals as well as bulk samples up to 1 kg and an volume of up to 45 cm x 50 cm x 8 cm. The light element detector allows the measurement down to carbon. There is a transport container which can be filled in the glovebox, so that the sample is not exposed to the ambient air at any time. The sample can be measured under (partial) vacuum and under helium purge, which gives the opportunity to meassure even liquids with vapour pressure or biological samples. A transmission image could additionally be recorded for each measurement. It is also possible to use m-XRF independently of single-crystal structure measurements.

Contact (SCXD)
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Details (SCXD)

Equipment

  • STOE StadiVari goniometer
  • DECTRIS PILATUS pixel detector (300 K)
  • Microfoci X-ray sources (Cu- and Mo-radiation)
  • Horiba XGT-9000 X-ray Fluorescence Analytical Microscope