Visualization of single heavy atoms by dark field electron microscopy.

Dark field electronmicrographs of atoms of palladium, iodine, platinum, osmium, and uranium in model compounds have been obtained. Statistical analyses and a series of blind tests demonstrate the validity of the results. Moreover, optical density measurements of the images indicate that the observed relative scattering cross-sections of these atoms agree well with the theoretical cross-sections calculated from a Thomas-Fermi-Dirac model of the atom.