Nanoscale Vibrational Spectroscopy in a Scanning Transmission Electron Microscope

Vibrational spectroscopy is a ubiquitous materials characterization technique in elucidating atomic structure of nanomaterials. The ability to perform high spatial resolution vibrational spectroscopy with an Ångström sized probe in a scanning transmission electron microscope (STEM) via electron energy-loss spectroscopy (EELS) is already impacting important scientific problems. Since the introduction of the technique in 2014, instrumentation development has continuously improved energy resolution, with 3 – 10 meV being presently available. Although this is poor in comparison to common vibrational spectroscopies, the spatial resolution offered by vibrational EELS is much better. This chapter serves as a brief review of common vibrational spectroscopies, after which it introduces and compares the physics of vibrational STEM EELS with these common techniques, followed by a succint review of the scientific problems that vibrational EELS has addressed.