This intriguing nanoscale image, called the Quantum Corral, was created by Donald Eigler, Crommie, and Christopher Lutz in 1993 at IBM’s Almaden Research Center. The team first used a scanning tunneling microscope (STM) to move iron atoms (which you see as turquoise mounds) one by one to form a corral on a copper surface. Inside the corral, trapped copper electrons, which ordinarily would move freely, form standing waves—waves that appear to be standing still.
After the iron atoms were in place, the team used the STM to scan back and forth over the sample to collect information about the contours of the surface, and the computer displayed the information as a black-and-white topographic map. Then, according to Don Eigler, “we used the computer to make it look like a real surface illuminated by light. We like to use color because it can help differentiate parts of the image and it’s more visually interesting.”
Eigler explains that a primary motivation for creating the Quantum Corral was “wanting the chance to visualize and study what electrons were doing inside very small structures.” The result is an image that shows the dual nature of electrons. “The individual iron bumps show the particlelike nature,” says Eigler; “the wave pattern you see in the interior shows the wavelike nature.”