Electron diffraction: concept, instrumentation and practical aspects

To showcase the enormous benefits of electron diffraction, ELDICO, in collaboration with internationally outstanding experts in the field of electron diffraction has set up a series of webinars. We kindly invite you to the introductory session, with Dr. Tim Grüne from University of Vienna.

To familiarize you a bit more with his research and the upcoming talk, we have carried out an interview where we addressed several important questions related to electron diffraction and its disruptive potential.

When: Nov 10, 2020 15:00 Zurich
Register in advance for this meeting here

1. What differentiates ED from other analytical techniques available at the moment?
T.G.: Electron crystallography has a long-lasting history, including the Nobel prize donated to Daniel Shechtman for his discovery of quasi-crystals. The productive application of electron diffraction to chemical crystallography is only about 1 1/2 decades young. As such, the method is undergoing heavy developments with great improvements.
Technically, electron diffraction can determine a single crystal structure from minute crystals – too small to see with the light microscope.

2. When did you start researching ED in more detail and why?
T.G.: My research in ED started in 2015. My background is X-ray crystallography, a field that has well matured. I am keen on methods development and electron crystallography and its application to organic and macromolecular compounds still has many open questions.

3. You published a collaborative research paper in Angewandte Chemie in 2018 that had a resounding success. Tell us more about its main points and the impact created.
T.G.: The publication in Angewandte Chemie aimed at demonstrating to X-ray crystallographers the benefit of electron diffraction as a complementary method for structure determination. The day it was published, four PIs from UCLA uploaded a manuscript (which was published about one month later) with the very same message. This coincidence boosted the attention of the community to the topic. It is great that the reviewers of our paper were very fast and that the editor realised the importance of the paper sooner.

4. What are the main applications of ED in academia and industry, now and in 5 years’ time?

T.G.: There are many diverse applications of ED. They cover materials science, chemistry, pharmacology. Heterogenous catalysts, e.g. zeolites, need to be very small to enlarge the relative surface. The grains are too small for X-ray crystallography, and ED permits to determine their crystal structure at their original size. In organic chemistry and pharmacology many compounds can be crystallized, but a substantial fraction remains a crystalline powder, too small for X-ray structure determination. Natural products are an important example, because they are often difficult to isolate or produce in large enough quantities for crystallisation trials.

5. What is your next big challenge and how do you plan to master it?
T.G.: Often, samples are sensitive to oxygen and unstable under vacuum. They are not conveniently prepared for ED, where the measurement takes place under vacuum. The samples need to be flash cooled to preserve their quality. With my background in protein crystallography, I have some ideas how sample transfer could be improved.

6. Who should invest in a dedicated electron diffractometer?
T.G.: Obviously, anyone with one of the above applications and also, experimental X-ray crystallographers involved in methods development.

Finally, synchrotron facilities and XFELs can determine X-ray structures from smaller and smaller crystals and since beam-time at these facilities is expensive, ED would make a great screening tool.