SEE DOWN TO 0.6 Å: Electron microscope achieves direct sub-angstrom imaging of a crystal

A MILESTONE IN ELECTRON microscopy—the first direct sub-angstrom imaging of a crystal lattice—has been reported by researchers at Oak Ridge National Laboratory and Nion, a company in Kirkland, Wash., that specializes in advanced electron-microscope optics { Science , 305 , 1741 (2004)}. The researchers fitted a 300-kV scanning transmission electron microscope (STEM) at ORNL with a Nion aberration corrector and made a number of other technical enhancements to the system, producing what they believe to be the highest resolution electron microscope in the world. In their images of a silicon crystal, they are able to distinguish columns of atoms that are 0.78 A apart. The actual resolution limit of the microscope is 0.6 A, according to team leader Stephen J. Pennycook, who heads ORNC's Electron Microscopy Group. This is a huge improvement over the resolution limit of 1.3 A that they had before the aberration corrector was installed, he adds. The team, which includes ...