Aberration-Corrected STEMs Open New Vistas

摘要

Since the electron microscope's inception in the 1930s, resolution limits imposed by electron lens aberrations have complicated its evolution. Compared with their visible-light counterparts, electron lenses are some 50x inferior. So while the ordinary microscope attained its resolution limit — close to the wavelength of visible light — about a century ago, this never quite happened for electron microscopy. Unsurprisingly, aberration correction became electron microscopy's Holy Grail because, although the wavelength used is several orders of magnitude smaller than that of light, it had not been possible to approach the wavelength of the electrons used (～0.03 A), which is considerably smaller than the average atom's diameter of 0.1-0.5 nm. Because e-beam resolution is limited to about 50 wavelengths, true atomic resolution was only achieved in the past couple of decades.