ADT with Precession – first crystal structure analysis

Citation

Enrico Mugnaioli, Tatiana E. Gorelik, Ute Kolb* (2009):
"Ab initio" structure solution from electron diffraction data obtained by a combination of automated diffraction tomography and precession technique.
Ultramicroscopy 109, 758–765 (2009)

In one sentence

The breakthrough paper that turned ADT from a data-acquisition technique into a structure-solution method, by combining it with precession electron diffraction (PED) and demonstrating ab initio structure determination on barite (BaSO4) directly from electron diffraction data.

What was done

The 2007 and 2008 ADT papers had established how to collect three-dimensional electron diffraction data from a single nanocrystal and how to extract its unit cell. The remaining open question was whether the integrated intensities — which in conventional electron diffraction suffer from strong dynamical (multiple scattering) contributions — could be used to solve a crystal structure ab initio, in the same way that X-ray diffraction intensities are routinely used.

The decisive step was to combine ADT acquisition with the precession electron diffraction (PED) technique introduced by Vincent and Midgley in 1994. By precessing the electron beam around the optical axis at each tilt, the integrated intensities become much closer to the kinematic ideal, and standard crystallographic direct methods can be applied. We demonstrated this on barite (BaSO4), a mineral with a well-known structure, allowing direct comparison with established crystallographic results. The full structure was solved without any prior structural input — purely from the electron diffraction data.

Ab initio structure solution of barite (BaSO4) from precession-ADT electron diffraction data

Why it matters

This paper marks the transition of ADT from a promising acquisition technique to a fully fledged structural-analytical tool. It established that nanocrystalline materials, previously inaccessible to single-crystal X-ray diffraction, could now have their atomic structures determined directly. Every later structure solved by 3D electron diffraction — across pharmaceuticals, zeolites, MOFs, minerals, and pigments — builds on the proof of concept established here.

Resources

Related on this site