The latter half of the twentieth century has opened to scientists an entirely new world: the world of atomic and subatomic particles. With the inventions of the electron microscope and the field ion microscope, scientists have been able to observe the microcosm as never before.

Until the early 1980s, however, one mystery that eluded researches was the nature of the surfaces of substances. Since the arrangement of atoms on the surface of a substance differs greatly from that of its bulk, it requires other methods of analysis. Scientists had lacked a mechanism for studying the intricacies of surfaces until 1981, when German physicists Gerd Binnig and Heinrich Rohrer invented the scanning tunneling microscope (STM).

The word tunneling used here describes an effect of quantum mechanics theorized upon for years and first verified in the laboratory in 1960. It was known that an electron orbits about the...