Abstract

Electron energy loss spectroscopy (EELS) carried out inside a scanning transmission electron microscope (STEM) provides a probe of elemental composition and bonding with atomic resolution. It allows us to map the local chemistry of a material. STEM EELS can tackle a wide variety of materials problems and has been used to identify single atoms, determine crystal phases, map dopants at grain boundaries and visualise plasmon modes. Combining experimental EELS with modelling can play an invaluable role in both the interpretation of experimental data and the design of experiments. Crucially, it can allow us to solve problems which experiment or modelling alone cannot. I will give examples including counting nitrogen-vacancies in nanodiamond [1] and using a combination of first principles structure prediction, EELS and diffraction to solve the structure of an unknown crystal phase at the interface of a metal and an oxide [2]. I will also talk about the latest developments which now mean it is possible to detect phonons and carry out momentum resolved vibrational mode measurements with nm spatial resolution [3].

[1] SLY Chang et al., Nanoscale 8 (2016) 10548-10552 [2] RJ Nicholls et al., Adv Eng Mater 17 (2015) 211-215 [3] FS Hage et al., Science Adv, accepted; RJ Nicholls et al., PRB accepted