Fan examines an image of an iodine-doped carbon nanotube that
he obtained at ORNL's Z-contrast scanning transmission electron
microscope (STEM), shown in the background. A computer model indicates
that a charged iodine chain in a nanotube sucks its excess electrons
from the tube wall, making the nanotube more electrically conductive.
world's sharpest electron microscope image of a crystal was recorded
recently at ORNL's Z-contrast STEM. This sub-nanoscale image of
a silicon crystal has double the resolution of TEM images. ORNL
physicist Steve Pennycook and Peter Nellist, now at the University
of Birmingham in the United Kingdom, made this image showing columns
of silicon atoms only 0.78 Angstrom apart. By contrast, typical
TEM images show columns of atoms no closer than 1.6 Angstrom apart.
One Angstrom is equal to one-tenth of a nanometer (or a billionth
of a meter).