XRD: Bruker Single Crystal D8 Venture
The Bruker D8 Venture is a single-crystal X-ray diffractometer. Its main use is to determine crystal structures, but it can also be used to measure powder diffraction patterns and make grazing incidence measurements. Our D8 Venture is equipped with two micro focus X-ray sources (Mo and Cu radiation), allowing very small crystals to be measured. The Mo radiation is best for fast high-resolution data collection and for charge density measurements. The Cu radiation is best for determination of absolute structures of light atom compounds. Another feature of the D8 Venture is its kappa four-circle geometry, which allows fast measurements with high completeness and multiplicity. Two different cooling systems are available for use with the D8 Venture: the Oxford Cryostream and the Oxford N-Helix. These enable cooling down to 100 K and 30 K, respectively.
Basic Operating Principles:
X-ray crystallography is based on the interaction of an X-ray beam with the electrons in a crystal. A perfect crystalline solid is made up of many repeating identical building blocks, known as unit cells, which are arranged in a three-dimensional crystal lattice. The crystal lattice behaves like a 3D diffraction grating, and when a beam of parallel monochromatic X-rays of the right wavelength strikes the lattice, a diffraction pattern is produced. The diffraction pattern is analyzed to determine the dimensions and shape of the unit cell. The determination of the arrangement of atoms in the unit cell requires further analysis, incorporating the relative intensities of all unique reflections in the diffraction pattern. The X-ray diffraction pattern consists of the superposition of scattered waves of varying amplitude, which can be measured directly, and phase, which must be calculated indirectly using numerical techniques. A crystal structure is considered solved when phase angles have been found that allow the atoms to be located such that the calculated diffraction pattern is a good fit to the experimental diffraction pattern. From here, further refinement of the structure can be made to obtain more detailed information about the atom arrangement.
D8 Venture Capabilities:
- General single crystal analysis
- X-ray crystallography is capable of unambiguously determining the complete three-dimensional molecular structures (including the absolute stereochemistry) of chemical substances.
- Choice of two wavelengths
- Mo radiation: high throughput and electron density measurements
- Cu radiation: absolute configuration determination of lightweight molecules
- Powder diffraction of capillary samples
- Cooling and heating of the sample (from 30 K to 400 K)
- Temperature dependent phase transfers can be studied
- Grazing incidence measurements
- IμS Microfocus Sources: Mo 0.71 Å, Cu 1.54 Å
- Four circle kappa geometry: high angular precision with a 7 μm sphere of confusion
- Photon 100 Detector: 100 cm2, 1024x1024 pixel
- Detector distance range: 35 mm to 239 mm
- Sample temperature: Cryostream 100K to 400K, N-Helix 30K to 300K
Restrictions on samples:
- Single crystal diffraction:
- If possible avoid benzene when growing crystals.
- Sample size from 10 μm to 120 μm (larger crystals can be cut).
- Single crystal is best. Bring everything you managed to grow. After optical inspection under the microscope, a decision is made by evaluating spot size and shape. A second evaluation is done after cell determination.
- Powder diffraction:
- Sample must be crystalline. Samples are measured in capillaries.
You will need at least two training sessions to be a qualified and authorized user on the D8 Venture and receive swipe card access to the room. In order to become a qualified user on the D8 Venture XRD, you need to follow each of these steps in the order as listed here:
- Complete the process to become a lab member of SNSF and follow the instructions to activate a Badger account.
- Complete the X-ray safety training.
- Send an email to Jana Maclaren to request training.
- Bring your own crystal to the training.
Optional further training on obtaining the structure from the data and finishing of the report for publication is possible.
As an alternative, we do offer a crystal measurement service for those who do not want to learn how to use the D8 Venture themselves. For further information, please contact Jana Maclaren.