Graz Advanced School of Science
PHYSICS COLLOQUIUM OF THE UNIVERSITY OF GRAZ AND THE GRAZ UNIVERSITY OF TECHNOLOGY
Prof. Dr. Quentin Ramasse
SuperSTEM Laboratory & University of Leeds
High-resolution electron energy-loss spectroscopy: how recent advances have now truly put a “synchrotron in the microscope”
At the dawn of the aberration-correction era, Prof. L. Mick Brown encouraged the microscopy community in now a seminal lecture to embrace and adopt widely this new technology, which promised, in his words, to place a “synchrotron in the microscope”. Although perhaps merely aspirational at the time, methodological and technological advances in the intervening decades, especially in the field of high (spatial and energy) resolution electron energy loss spectroscopy (EELS), have arguably made this vision come true.
By pushing the energy resolution of state-of-the-art scanning transmission electron microscopes (STEMs) below 10meV while maintaining atomic-sized probes, and in combination with a step change in detection technology, the chemical and electronic structure of a wide range of materials systems can be directly determined with unprecedented detail, across the energy scale from the core-loss to the vibrational spectroscopy regimes. It is possible to fingerprint the bonding of single impurity atoms as well as their localised vibrational signature, offering insights into how the smallest building block of matter can affect overall properties of materials. Encouraging steps have been taken recently towards the ability to map electronic states (orbitals) in real space at the atomic scale; exploring momentum space while balancing probe size (spatial resolution) opens a unique nanoscale experimental space to study the dispersion behaviour of excitations in materials; and there are early experimental hints that beyond vibrational spectroscopy, excitations such as magnons, periodic oscillations of the spin of charge carriers in materials, can be detected in the STEM, perhaps even at atomic resolution.
Date: Tuesday, March 11th, 16:15
Location: Lecture Hall P2, Petersgasse 16, Graz University of Technology
Host: Gerald Kothleitner
For a regularly updated colloquium program see: https://www.if.tugraz.at/colloquium.html
