Electron energy-loss spectroscopy (EELS) in scanning transmission electron microscopy (STEM) is arguably one of the most versatile spectroscopy techniques to study materials at (sub)nanometer length scales. For many decades, EELS has been used to measure sample thick-ness, obtain elemental chemical compositional maps and extract the bonding information of mate-rials with unprecedented spatial resolution [1].
The recent development of a new generation of monochromators [2] and spectrometers [3] has made EELS even more versatile. Phonon mapping with atomic resolution [4,5], and the detection of isotopes in water [6] and amino acids [7] are now some of the new frontiers of EELS.
Similarly, the recent development of “pixelated cameras” with high electron sensitivity and high-dynamical range allow the routine acquisition of 4D-STEM data sets, resulting in the mapping of local electric fields and charge densities at sub-angstrom spatial resolution [8-11].
Here, I will present a few examples of the aforementioned advances in EELS and detectors that now allow to measure excitonic and magnetic properties of materials with unprecedented spatial resolutions, opening the door for our understanding of matter at new level. I will discuss in de-tails our current data analysis workflows, highlighting the bottlenecks, and pointing out, (on my opinion), where further improvement for on-the-fly and in-depth data analysis can significantly reduce the time window between an initial conceptual experiment and publication.
Acknowledgements: This research was supported by the Center for Nanophase Materials Scienc-es, which is a DOE Office of Science User Facility. This research was conducted, in part, using instrumentation within ORNL's Materials Characterization Core provided by UT-Battelle, LLC, under contract no. DE-AC05-00OR22725 with the DOE, and sponsored by the Laboratory Di-rected Research and Development Program of Oak Ridge National Laboratory, managed by UT-Battelle, LLC, for the U.S. Department of Energy.
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