The impact of STEM aberration correction on materials science.

Over the last three decades the scanning transmission electron microscope (STEM) has gone from a specialized instrument for nanoscale analysis to the microscope of choice for atomic resolution imaging of materials, allowing incoherent high-angle annular dark field (Z-contrast) imaging, coherent phase contrast modes (conventional and annular bright field), electron energy loss and energy dispersive X-ray spectroscopy. All signals are achieving atomic resolution and several are available simultaneously. This would not have been possible without the development of an aberration corrector for the STEM, spearheaded by Ondrej Krivanek in the late 1990s, which finally allowed the benefits of the STEM to translate from "in-principle" to actual daily practice. Here I will recall my own experiences with the aberration-corrected STEM in partnership with Ondrej, a truly exciting and rewarding journey.