Heinrich Rohrer jointly won half the Nobel Prize in Physics in 1986 with Gerd Binnig "for their design of the scanning tunneling microscope.” The other half of the prize went Ernst Ruska "for his fundamental work in electron optics, and for the design of the first electron microscope." Heinrich Rohrer’s specialty is in condensed matter physics. Scanning tunneling microscopes function because of electrons tunneling or going through potential energy barriers. This can result when an atom is in an electric field and the electron escapes from the atom. Metals have closely spaced energy levels for their valence electrons. These energy levels are called conduction bands. The valence electrons easily go from one metal atom to another. For the scanning tunneling microscope, a metal tip is brought near a metal surface. Electrons “tunnel” through causing a current from the surface through the tip of the microscope. This allows the surface of the material to be observed at much greater resolution than an optical microscope. Scanning tunneling microscopes can be used to image and manipulate an individual atom.