Electron crystallography

Abstract

The idea of solving unknown crystal structures from experimental electron-diffraction intensities and high-resolution electron micrographs has remained a controversial topic in the 60 year history of electron crystallography. In this review it will be shown that the application of modern direct phasing techniques, familiar to X-ray crystallographers, has decisively proven that such ab initio determinations are, in fact, possible. This statement does not, by any means, refute the existence of the several significant scattering perturbations identified by diffraction physicists. Rather, it does affirm that experimental parameters can be controlled to ensure that a 'quasi-kinematical' data set can be collected from many types of specimens. Numerous applications have been made to various types of specimens, ranging from small organics to proteins, and also some inorganic materials. While electron crystallography may not be the optimal means for determining accurate bonding parameters, it is often the method of choice when only microcrystalline specimens are available.

3D Electron Diffraction: The Nanocrystallography Revolution

“…6,7 In diffraction data, the structure information dwells in the relative differences between reflection intensities, and it is evidently lost or jeopardized when such intensities are leveled out, or their ranking is scrabbled due to multiple scattering. ED experienced a true rebirth in the past 20 years of the past century, thanks to the research of Dorset and co-workers 8,9 and Hovmoller and co-workers, 10,11 that demonstrated how ED data acquired in a transmission electron microscope (TEM) can be used for the structure characterization of both organic and inorganic nanocrystalline samples, despite the presence of dynamical effects. Shortly after, Gonen et al 12 also showed that ED can be used for the structure determination of 2D protein crystals at almost-atomic resolution.…”

3D Electron Diffraction Structure Determination of Terrylene, a Promising Candidate for Intermolecular Singlet Fission

“…The strong interaction of electrons with matter has attracted a growing interest since late 1900s, when it became evident that electron diffraction (ED) data acquired by a transmission electron microscope (TEM) can be used for the structure determination of nanocrystals. [ 1 , 2 , 3 , 4 ] A crucial methodological breakthrough was the development of routines for sequential acquisition of 3D diffraction data, after tilting the sample in fixed angular steps around an arbitrary axis. [ 5 , 6 , 7 , 8 ] The resulting data set can thus be used for the determination of cell parameters and Laue class, as well as for the integration of reliable reflection intensities.…”

Electron Diffraction of 3D Molecular Crystals

“…15 Nevertheless, it was not until Dorset's retroactive validation of Vainshtein's work in the 1990s that the stigma surrounding multiple scattering began to dissipate. 16 ED then experienced a belated resurgence in activity in the mid-2010s, driven by methodological and hardware-based advances which enabled collection of diffraction patterns minimizing the deleterious influence of multiple scattering. 17 Nearly a century after Davisson and Germer, ED now appears poised to reclaim its mantle as one of the most promising techniques for structure elucidation of 3D molecular crystals.…”

“…An excellent summary of their work is available in Vainshtein’s 1964 monograph Structure Analysis by Electron Diffraction , which details >30 3D structures, ranging from inorganic salts to organic small molecules, methodically solved by electron diffraction . Nevertheless, it was not until Dorset’s retroactive validation of Vainshtein’s work in the 1990s that the stigma surrounding multiple scattering began to dissipate . ED then experienced a belated resurgence in activity in the mid-2010s, driven by methodological and hardware-based advances which enabled collection of diffraction patterns minimizing the deleterious influence of multiple scattering .…”