Manipulated atom image
Colourized version of an image created by the NIST custom-built scanning tunnelling microscope as it drags a cobalt atom across a closely packed lattice of copper atoms. Large round features show the cobalt atom bonding to the copper at its preferred, lowest-energy bonding site. Bright triangle-shaped areas show the atoms bonding at a higher-energy site. The atom "screeches in protest" when the STM tip forces it to sit at this site. Dark areas show positions that the atom "hops" over, refusing to bond at all.
Credit: Joseph Stroscio; Robert Celotta/NIST