Electron microscopy has advanced very significantly in the last two decades. Electron-optical correction of aberrations, which we introduced for the scanning transmission electron microscope (STEM) in 1997, has allowed STEMs to reach sub-Å resolution from 2002 on. It has led to new STEM capabilities, such as atomic-resolution elemental mapping, and determining the type of single atoms by electron energy loss spectroscopy (EELS) and energy-dispersive X-ray spectroscopy (EDXS). More recently, we have focused on Ultra-High Energy Resolution EELS (UHERE). We have developed a monochromator and a spectrometer that use multipolar optics similar to the optics of aberration correctors, plus several stabilization methods, and we have reached <5 meV energy resolution at 30 keV primary energy. This has opened up a new field: vibrational spectroscopy in the electron microscope. When collecting large-angle scattering events, vibrational spectroscopy can lead to sub-nm spatial resolution, and when collecting small-angle scattering angle events, it can produce EEL spectra with the electron beam positioned tens of nm away from the probed area. The second geometry has led to a powerful new technique: aloof vibrational analysis of materials, which avoids significant radiation damage. Even more recently, we have focused on combining the analytical techniques with in-situ sample treatment. Our progress includes cooling the sample to liquid N
2 temperature in a side-entry holder capable of reaching better than 1 Å resolution. My talk will review these developments, and illustrate them by application examples.
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