Time:
11:00
Location:
Sala Sancrotti, Building Q2, in AREA Science Park – 34149 Basovizza, Trieste ITALY
Speaker:
Daniel Knez – Institute of Electron Microscopy and Nanoanalysis (FELMI)
Abstract:
In 1997, L. M. Brown predicted that advances in resolution, detectors, and spectrometers for transmission electron microscopes (TEM) would turn the TEM into a universal characterization tool, akin to placing “a synchrotron in a microscope”.
Now, 27 years later, aberration-corrected electron optics, novel detection techniques, and advanced computational capabilities have indeed transformed TEM, particularly scanning TEM (STEM), into one of the most powerful characterization tools in both material and life sciences. Its versatility lies in the availability of various imaging and diffraction modes, as well as analytical techniques like electron energy-loss spectroscopy (EELS) and energy-dispersive X-ray spectroscopy (EDXS). These methods enable the atomic-scale determination of structure, elemental composition, and chemical bonding, leading to significant breakthroughs in understanding fundamental phenomena in physics, chemistry, and materials science.
However, atomic-level structural and chemical characterization, such as impurity detection or point defect analysis, is often limited by challenges in sample preparation, low signal-to-noise ratios (SNR), and the high current densities introduced by highly focused electron beams. These factors can cause gradual, often unrecognized, specimen transformations, particularly when applying atomic resolution imaging and spectroscopic techniques that require higher acquisition doses. As a result, many sensitive material systems—such as battery materials, biopolymers, nanoporous materials, and nanoclusters—demand the development of new methodologies in preparation, characterization, and data analysis.
This seminar will provide an overview of analytical strategies designed to address these challenges, showcasing research examples from various nanoscale material systems. Topics will include atomic-scale lithiation processes in LiFePO4, structural analysis of cellulose nanocrystals, mapping of electronic states and oxygen vacancy distributions in complex oxide thin films, and the three-dimensional localization of single atoms in beryl pores.
Special attention will be given to low-dose imaging and diffraction techniques, as well as the advantages of modern direct detection EELS.