Speaker
Description
Molecular crystals with macroscopic flexibility have shown tremendous potential for applications as flexible optical waveguides, fluorescent materials, piezo- and ferroelectrics, semiconductors and drug tablets in the last decade.[1 and references therein] μ-X-ray diffraction technique employing synchrotron radiation has been used to understand the underlying mechanisms of deformation.[2] However, inherent disadvantages of the method preclude quantification of underlying defects under strain.
3D electron diffraction is an emerging technique that has revolutionised nanocrystallography.[3] Exploiting the property of electrons that it interacts 104 times as compared to X-rays as well its ability to probe structures of submicron-sized crystalline samples, we have employed the technique to map deformations in mechanically deformed crystals of some molecular crystals.
In this contribution, we will demonstrate how 3D ED has aided in accurate atomic resolution studies by successfully performing structure solution and refinement against 3D ED data collected on mechanically deformed crystals. Furthermore, dynamical refinements reveal valuable physical information with respect to the variation of mosaicity of the different regions of a perturbed crystal.
This is the first demonstration of the enormous potential of 3D ED to probe atomic-scale perturbations in pliable molecular crystals. The implications of this study are enormous with respect to (i) use of laboratory-based TEM technique to complement large-scale facilities such as synchrotron and (ii) investigations of perturbations in pharmaceutical materials due to tabletting.
References:
[1] Z. Zhou et al. (2022) Chem. Eng J. 450, 138333.
[2] A. J. Thompson et al. (2021) CrystEngComm 23, 5731.
[3] M. Gemmi et al. (2019) ACS Cent. Sci. 5, 1315–1329.