Contact: Prof. Ursel Bangert
Bernal Chair of Microscopy and Imaging,
& Dr Andrew Stewart
Department of Physics and Energy,
University of Limerick
E-mail: Ursel.Bangert@ul.ie & Andy.Stewart@ul.ie
There has been a breakthrough in robust structure solutions by combination of precession and automated diffraction tomography (ADT). Since 2009 over 60 structures have been solved using this method (which is more structures than have been identified during the whole of electron diffraction applications in the previous 50 years). A whole range of structures from geology specimens, inorganic, organic, pharmaceuticals, MOF's, COF's. Polyphasic powders, can also have the individual phases identified and solved, where powder diffraction cannot do the job; for example in several instances minor phases that have not been noticed in the powder pattern have been identified and solved by this method. ADT is a significant new tool for elucidating crystal structures in the electron microscope allowing crystals of 30 to 400nm to be used for a single crystal structure solution. This tool is further being developed at UL’s transmission electron microscopes (TEM) with the extension of the technique into the world of protein crystallography, which is being made possible with developments in sample handling and newer more sensitive electron detectors.
|(a) Image of FeSi2 Crystals fused together with an amorphous layer.||(b) Reconstruction of the reciprocal space volume from ADT data.|
From Imlau et al. PHYSICAL REVIEW B 89, 054104 (2014)
The combination of x-ray powder diffraction and electron diffraction is fast becoming a new way of determining crystal structures of the most challenging and interesting Nano scale materials.
Current cooperation exists with the University of Patras (Greece), Monash University (Australia), the University of Alabama (Tuscaloosa, USA) as well as with the ER-C in the Forschungszentrum Juelich (Germany) regarding technique development and with industrial partners (Nanomegas) regarding detector development. It is anticipated that there will be large interest in this method from the pharmaceutical and bio-engineering sector in research and industry, especially in Ireland.