X-ray Diffraction

X-ray diffraction (XRD) is the definitive technique for studying crystalline matter. Diffraction experiments can be done on powders to provide relative quantitation on the levels of different crystalline minerals present, or on single crystal specimens to determine the molecular structure of the crystal at atomic resolution.

At JBL Science we have high-throughput as well as variable temperature and humidity options for powder diffraction to analyse reactions or changes in crystalline forms as a function of environment.

A dual source (Cu/Mo) single crystal diffractometer allows for different wavelengths of x-rays to extend the scope of the analyses. This instrument is cryo cooled to increase data quality whilst a plate stage allows for fast screening of crystals from different solution conditions.

When X-rays are directed at a sample they are reflected from the electrons of the atoms.

When the sample is crystalline, i.e. has long range order, these reflections constructively and destructively interfere with each other giving rise to a specific pattern that is measured. This pattern depends on the internal order of the sample and can be considered like a fingerprint of a crystalline material.

Comparison to a database of known patterns helps identify the material in question. Since the X-rays are reflected from the electrons, X-ray diffraction does not give direct evidence on the elements in the material.

The analysis of single crystals allows for the determination of the atomic positions in the crystal from the diffraction pattern. This gives rise to accurate molecular elucidation with information on bond lengths and angles in the molecule as well as intermolecular interactions.

Quantitative analysis of mixed powder samples, for example historical mortar and paint analysis.

Characterisation of crystal forms in pharmaceutical dosage forms.

Variable humidity and temperature measurements of materials.

Crystal structure elucidation from single crystal samples.

Any crystalline material. Typically powdered samples are analysed but homogeneous discrete samples can also be analysed.

Sample amount requirements vary with analysis and sample type but typically around 20 mg is needed. The method is non-destructive.