Diamond Light Source
Beamline I19 - Small Molecule Diffraction

Single-crystal X-ray diffraction techniques are considered the definitive means of determining the structure of a molecular material. It is an indispensable pillar of synthetic chemistry as it provides definitive confirmation that a target material has been formed. X-ray crystallography, using single-crystal methods, also provides the most accurate means of following the response of a molecular structure to an external influence such as the variation of the thermodynamic variables of pressure and temperature, photo-excitation or, for porous systems, the exchange of a gas.

The high photon flux offered by the beamline allows crystal structure studies of samples that are too weakly scattering, due to either their size or the complexity of their underlying molecular structure, to be successfully carried out using any other X-ray source. These studies underpin chemistry and materials science in strategically important areas such as:

  • Energy storage and carbon capture materials, e.g. metal organic framework systems
  • Pharmaceutical science
  • Supramolecular chemistry and self-assembly systems
  • Superconducting and magnetic materials

The photon energy can be tuned in the range 5 keV to 25 keV (corresponding to a wavelength range of 2.5 Å to 0.5 Å) with a bandpass of 10-4. This energy tuning capability, which is unique to synchrotron sources, allows crystallographic studies using anomalous dispersion techniques. The narrow bandpass provides sufficient resolution to discriminate specific oxidation states of heavy elements.

Apart from structural chemistry studies, which are carried out in EH1, the beamline offers a variety of sample environment equipment in EH2 allowing structural changes to be mapped under the influence of an external effect. The techniques include:

  • Variable temperature studies using open-flow and closed-cycle cryostats, and an open-flow furnace
  • Variable pressure studies using diamond-anvil cells
  • Gas exchange in porous materials
  • Time-resolved studies of photo-excited states

Beamline Energy Resolution
2 * 10-4 [meV] @ 0 [eV]
Beamline Resolving Power
2 * 10-4 [deltaE/E] @ 18 [eV]
Beamline Energy Range
5 - 25 [eV]
Max Flux On Sample
2.6 * 1012 [ph/s] @ 12.4 [eV]
Spot Size On Sample Hor
90 - 120 [um]
Spot Size On Sample Vert
60 - 80 [um]
Divergence Hor
0.4 [mrad]
Divergence Vert
0.05 [mrad]
Angle Of Incidence Light On Sample Value
6 [degrees]
Dave Allan
  • Crystallography
  • Time-resolved studies
Emission or Reflection
  • X-ray fluorescence (XRF)
  • Elastic scattering
control/Data analysis
Control Software Type
  • GDA, Rigaku CrystalClear, Agilent/ Newport CrysAlis IS IS4CCD
Data Output Type
  • diffraction images for crystallographic studies
Data Output Format
  • ascii for reduced data (hkl and ins files), ascii/tiff for raw image data
Softwares For Data Analysis
  • Rigaku CrystalClear, Agilent CrysAlis Pro, Bruker Apex II