Unzipping a Surface
Surface chemistry at work: a series of pictures made by a scanning tunneling microscope reveals an equilateral triangle, only about 1000 atoms across,"unzipping" as chemicals burrow into an atomic-scale defect on the face of a silicon wafer, called a dislocation. The chemicals strip away the layers of the silicon to a depth of 120 atoms.The bottom of the triangle is perfectly flat. (An optical illusion makes the layers appear to be growing upward, when actually each layer is deeper into the wafer.)