Which instrument earned Gerd Binnig and Heinrich Rohrer the 1986 Nobel Prize in Physics?

The scanning tunneling microscope earned Gerd Binnig and Heinrich Rohrer the 1986 Nobel Prize in Physics.

The instrument images conductive surfaces by scanning a very sharp tip across them while measuring a quantum tunneling current. Because the current changes sharply with distance, the microscope can reveal atoms on a surface.

Binnig and Rohrer developed the microscope at IBM’s Zurich Research Laboratory, and the first working instrument was built in 1981. Its operation depends on quantum tunneling rather than visible light or ordinary geometric contact.

The 1986 Physics prize was shared with Ernst Ruska, who received half for designing the first electron microscope. A scanning tunneling microscope is therefore not simply a higher-powered optical or electron microscope.