A National Electron Diffraction Facility for Nanomaterial Structural Studies

Electron diffraction (ED) is about to become a quantitative technique that will be used routinely to solve and refine crystal structures from extremely small specimens. These materials are, at best, difficult to tackle with X-ray diffraction (XRD) and many are completely beyond the reach of current capabilities. The very different physics of electron scattering means that structures of crystals with grain sizes smaller than a micrometre, and materials containing light elements like hydrogen and lithium, can be solved.

This step-change will be made possible by taking the methods and detectors currently used for XRD, which have been developed over decades to a high level, and combining them with a purpose-built electron diffractometer. The resulting equipment allows routine analysis of nanoscale materials. This new technology opens many doors, in some fields saving months of work in crystallisation and crystal growth. Unsurprisingly, there is intense interest both on a national and international level.

Electron diffraction itself is not new, but the factors that allow it to reach beyond XRD, particularly multiple scattering, need to be considered when modelling the data produced in these measurements. This is still very much a work in progress, and it will be essential to bridge the gap between disciplines, bringing in knowledge and methods from electron microscopy, to develop the method to its full potential.

These machines have become commercially available only in the last year. To remain competitive in structural science, the UK must invest in this area, and can take a global lead by doing so promptly. The widest benefit of this new capability for UK researchers will be provided by a national facility for ED that has both capacity and expertise to develop this nascent technology for routine and widespread use.

The National Crystallography Service (NCS) at the University of Southampton (UoS) is well-placed to deliver such a facility, building on its success in routinely providing structure solution and refinement using high-value equipment that is unavailable to most researchers in their home institutions. The University of Warwick (UoW) has nationally leading electron microscopy and XRD facilities with a proven success in offering multiuser access. UoW also has a leading position in modelling and developing ED techniques and brings a suite of methods (cryogenic holders, heating holders, MEMS-based in-situ holders, graphene oxide support films) that will extend ED capabilities into new areas. Together, UoS and UoW will provide a dual site, single national facility that will build on existing world class lab infrastructure, deliver the technique immediately at both national and local scale, and develop the method going forward to take advantage of this opportunity for the UK.

Four areas are identified as having the most to gain immediately from new ED techniques: pharmaceuticals; metal-organic frameworks; inorganic materials and molecular solids. Industry, in particular Pharma, realises the impact of ED and is keenly expressing a need for access to the technique.

There is therefore strong support for the proposed facility from both academia and industry, and leading representatives from these communities in the UK have agreed to form an independent ED working group and act as champions to promote the method and facility. To understand how ED should develop, matching capacity and capabilities to the needs of the UK science community, the working group and the UoS/UoW team will undertake a landscaping exercise that will align with NCS national access cycles. This will allow new communities to be identified and aid strategically informed investment to grow UK capacity and research in the fundamental and essential area of atomic structure determination.

The timing for this facility is ideal as ED technology now becoming available aligns with swathes of research communities demanding it.