Chromatic- and geometric-aberration-corrected TEM imaging at 80 kV and 20 kV

The interest in light-element nanomaterials stimulated the development of atomic-resolution low-voltage transmission electron microscopy. While geometric-aberration correction made high-resolution imaging at around 80-kV electron acceleration voltage possible, imaging at substantially lower voltages requested the development of chromatic-aberration correction in addition. Recently, the SALVE instrument was introduced with the capability of atomic resolution imaging at electron acceleration voltages from 80 kV down to 20 kV. Here, we show on the example of imaging graphene that at these electron energies, the residual geometric aberrations reintroduce contrast oscillations and delocalization. Also, we show an atomically resolved image of a single vacancy in graphene with a pronounced Jahn-Teller distortion.