Electron crystallography

The term electron crystallography joins all the crystallographic studies carried out using electrons as a probe either in diffraction or in imaging. The ZEISS Libra 120 transmission electron microscope at the   CNI@NEST has been configured as an electron diffraction station for electron crystallography studies.

Electron diffraction tomography: this research activity is focused on the precession assisted electron diffraction tomography (PEDT) method for its application to very beam sensitive materials as organics, pharmaceutical and proteins. On “hard” inorganic materials our electron crystallography station is already able to furnish diffraction data suitable for both structure solution and refinements on crystal as small as few hundreds of nanometers (dynamical refinement). We are actually developing a completely automatic data collection procedure ( Fast EDT) that, coupled with a new direct electron diffraction camera ( MEDIPIX), will allow fast data collections in less than 1 minutes drastically reducing the dose suffered by the sample. We expect in the very near future to be able to collect in this way data on vitrified samples containing protein nanocrystals which will be suitable for solving the protein crystal structure. 

Nano texture analysis: this activity is based on the ASTAR system for collecting phase and orientation mapping. We are trying to increase the resolution and the data collection speed by using the MEDIPIX detector as recording device. Exploiting its sensitivity we expect to bring the resolution down to the minimum beam size available of 1.4 nm.  Possible applications: polytypism at the nanoscale of pharmaceutical, evaluation of the nanocrystalline amorphous ratio in beam sensitive samples.

3D reconstruction of the reciprocal space of CaFe2O4

3D reconstruction of the reciprocal space of CaFe2O4

Correlative TEM Micro-CT

The lab is developing a new correlation method between X-Ray tomography (Micro-CT, in collaboration with SYRMEP beamline at Elettra - Sincrotrone Trieste) and transmission electron microscopy. The tomographic 3D reconstruction of whole organs and/or tissue already embedded and fixed for TEM analysis allows the identification of region of interest (usually pathological hallmarks) with the intrinsic resolution of few microns characteristic of Micro-CT. The sample can then be cut with the ultra-microtome just across the identified region of interest for obtaining a this section suitable for TEM imaging, avoiding the time-consuming method of serial sectioning and the loss of regions that could be important in the characterization of particular models of unpredictable pathologies in which ROIs are randomly localize within the sample.

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