Electron Crystallography research line develops new transmission electron microscopy techniques for the investigation of inorganic, organic and biological materials. Thanks to the strong interaction of the electrons with matter and the capability to focus electrons in nanometric bright beams, electron diffraction is the only single crystal diffraction technique that can be performed on nanocrystals. Our TEM (Trasmission Electron Microscopy) has been modified in order to collect 3D electron diffraction data (electron diffraction tomography) EDT on any kind of nanocrystalline material. The data collection procedure has been automatized and optimized in order to perform fast measurements even on materials sensitive to strong electron beams. Our field of investigation spans from mineralogy to solid state chemistry, from organic crystallography to protein structure determination.

Low crystallinity and nanodomains

The capability of collecting automatic 3D single crystal EDT data with high spatial resolutions (150 nm) allows investigating structural problems for low crystallinity and small size single crystal domains ( Gemmi et al. 2015). A material with ordered domains of a few hundreds of nm can be studied as a collection of single crystals on which we can collect 3D EDT data about structure quality. Nanoparticles embedded in a matrix, amorphous or not, and crystals with polytypic sequences at the nanoscale can be also studied. For the first time using powder diffraction methods, we have the possibility to study the solid state at a scale at which only an average description was available, until now ( Gemmi et al. 2016).

EDT on beam sensitive materials

Beam sensitive materials are a challenging class of materials to be investigated by EDT, unfortunately, a lot of crystalline materials with high scientific and commercial impact belong to this category. Dealing with Material Sciences, the most promising ones are zeolites and MetallOrgainc Framework (MOF), while, concerning organic compounds, pharmaceutical substances and proteins are definitely the most interesting ones. In addition to beam sensitivity, a common issue in structure investigation of these materials is the difficulty in obtaining large single crystals. Therefore, EDT is a perfect candidate for a breakthrough in crystal structure analysis. We developed a fast EDT procedure that, combined with a new generation single electron diffraction camera (MEDIPIX2 detector acquired thanks to a Regione Toscana contribution), allows fast data collection with dose lower that 0.05 e/(Ųs). In this way, all the materials described above can be studied with EDT before the amorphization by the electron beam occurs and on a scale never reached by other diffraction techniques ( Simancas et al. 2016).

Correlative Micro-CT and TEM imaging

We are developing new TEM methods for the observation of biological samples. The aim is to develop a technique that, in cases of pathologies spread across entire organs or districts, gives a global view at low resolution and a local view at ultrastructural level at the same time. In order to reach this goal, we designed a correlation method between X-Ray tomography (Micro-CT, in collaboration with SYRMEP beamline at Elettra - Sincrotrone Trieste) and TEM ( Parlanti et al. 2017).

Libra 120 transmission electron microscope equipped with:

• In colum omega filter for energy filtered imaging and EELS spectroscopy
• HAADF detector for STEM imaging
• Digistar P1000 device for precession electron diffraction
• ASI Timepix2 single electron detector for diffraction
• Double tilt, rotation double tilt, single tilt liquid nitrogen cryo transfer holders
• Bruker Xflash 6T SDD EDS detector
• Leica UC7-FC7 cryo ultramicrotome
• Leica EMPG cryo plunging system
• High resolution powder diffractometer (soon)

• Prof. Lara Righi Dipartimento di Scienze Chimiche, della Vita e della Sostenibilità Ambientale, Università di Parma.
• Prof. Luigi Folco Dipartimento di Scienze della Terra, Università di Pisa, Italy.
• Dr. Lukas Palatinus Czech academy of Science, Prague, Czech Republic.
• Dr. Tim Gruene PSI, Villigen Switzerland.
• Ana M. López-Periago, Instituto de Ciencia de Materiales de Barcelona (ICMAB-CSIC), Bellaterra,  Spain
• Isabella Pignatelli, Université de Lorraine Vandoeuvre-lès-Nancy, France
• Péter Németh, Institute of Materials and Environmental Chemistry, Research Center for Natural Sciences, Hungarian Academy of Sciences, Budapest Hungary
• Fernando Rey, Istituto de tecnologia quimica, Valencia Spain.