X-Ray Crystallography

Apex2 Kappa CCD X-ray Diffractometer (Brüker AXS)

The Apex2 Kappa CCD 4-Circle Kappa FR540C diffractometer (Brüker AXS) is equipped with an Apex2 CCD based detector cooled to -60°C using graphite monochromated Mo-K radiation { 17.44 keV; (Mo-K): 0.71073 Å} from a sealed fine-focus ceramic tube X-ray tube and a FR591 HV generator. The system uses a horizontal-oriented Kappa 4 circle goniometer with 2-theta, omega and phi drives and a motorized DX track for setting the detector distance. With the kappa angle, the crystal can be oriented at chi from 0° to 92°. A 0.35 mm fine focused collimator is used. Two computers are used in the system. One (Bruker54) is used to run the diffractometer and collect data and is a slave to the primary computer (Bruker55) which contains the Apex2 software for processing data. In principle, Bruker54 could collect and process the data, but usually data is transmitted to Bruker 55 as it is collected.

The data collection can be performed at ambient temperature or at lower temperatures (as low as -183 °C) using a cold nitrogen gas stream. Most data is collected at -100 °C

Specifications

Generator 55 kV
50 mA
Small molecules: 30 mA, 50 kV (1.5kW)
Theta axis -45 to +66° (accuracy: ±0.010°)
Omega axis -210 to +210° (accuracy: ±0.010°)
Kappa axis -175 to +175° (accuracy: ±0.010°)
Phi axis -360 to +360° (accuracy: ±0.015°)
Crystal size 0.2 to 0.3 mm for organic compounds. Use smaller sizes for compounds containing heavier atom (e.g. Fe, Pb, Pd) to reduce absorption effects (0.15 to 0.10 mm).
Limit: 0.04 mm in one dimension only.

More Information

Crystals should be checked under the polarizing microscope located within the X-ray facility. A good crystal will extinguish completely on a distinct position when between crossed polarization filters.

Data collection, integration, scaling, structure solution and refinement is achieved with the Windows 7 based Apex2 system of programs (Bruker AXS).

Research Applications

  • Identification and characterization of materials
  • Observing changes in structure as a function of temperature, pressure, magnetic field, or reactants
  • Determination of molecular structure and geometry

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