Brave New Nanoworld

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Z-contrast scanning transmission electron microscope image (left) of iodine atoms in a carbon nanotube (visualized above).

Xudon 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.

The 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).