ABSTRACT: Modern scanning and transmission electron microscopes (S/TEM) are now almost ubiquitous in materials and biological sciences laboratories. They have radically enhanced our understanding of organic and inorganic matter with the successful development of aberration correctors [1,2], detectors with film-equivalent dynamical range [3], and more recently, with monochromators capable of achieving sub-10 meV energy resolution spectroscopy [4]. Improvements in the understanding of the scattering process involved in EELS have resulted in the ability of EELS to measure and quantify ferromagnetic phases in materials, as it is done with X-ray circular dichroism in synchrotrons, but with the phase of the electrons playing the role of polarization of light [5]. Phonon mapping with atomic resolution [6,7], primary temperature measurements at the nanoscale (without requiring any previous knowledge of the sample) [8], and the detection of isotopes in water [9] and amino acids [10] are now some of the new “tools” in this Swiss Army knife of spectroscopy that is EELS. Here, we will review the technical details of the aforementioned tools. We will discuss potentially relevant new “blades” that could be added to the EELS toolkit, to accelerate the discovery of new physical phenomena and sharpen our understanding of how matter behaves [11, 12]. [1] J. Zach and M. Haider, Optik 99 (1995), p. 112. [2] O. L. Krivanek, et al, Institute of Physics Conference Series 153 (1997), p. 35. [3] A. R. Faruqi, R. Henderson, Curr. Opin. Struc. Biol. 17 (2007), p. 549. [4] O. L. Krivanek, et al, Phil. Trans. R. Soc. A 367 (2009), p. 3683. [5] P. Schattschneider, et al., Nature 441 (2006) p. 486. [6] K. Venkatraman et al., Nat. Physics 15 (2019) p. 1237. [7] F. S. Hage et al., Science 367 (2020), p. 1124. [8] J. C. Idrobo, et al, Phys. Rev. Lett. 120 (2016), p. 095901. [9] J.R. Jokisaari, et al., Adv. Mater. 30 (2018), p. 1802702. [10] J.A Hachtel, et al., Science 363 (2019), p. 525. [11] J.C. Idrobo, Nat. Rev. Mater. 6 (2021), p. 100. [12] This research was supported by the Center for Nanophase Materials Sciences, which is a Department of Energy 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 U.S. Department of Energy. |