Atomic-Resolution Imaging with a Sub-50-pm Electron Probe

Using a highly coherent focused electron probe in a fifth-order aberration-corrected transmission electron microscope, we report on resolving a crystal spacing less than 50 pm. Based on the geometrical source size and residual coherent and incoherent axial lens aberrations, an electron probe is calculated, which is theoretically capable of resolving an ideal 47 pm spacing with 29% contrast. Our experimental data show the 47 pm spacing of a Ge 114 crystal imaged with 11%-18% contrast at a 60%-95% confidence level, providing the first direct evidence for sub-50-pm resolution in annular dark-field scanning transmission electron microscopy imaging.