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Scanning Tunneling Microscope

The incredible advance in microscopy of being able to see objects as tiny as individual atoms was achieved by physicists Heinrich Rohrer and Gerd Karl Binnig. The pair developed the scanning tunneling microscope in 1981 while working for IBM in Zurich, Switzerland.

Binnig was born in Frankfurt, Germany, on July 20, 1947. He studied physics at J.W. Goethe University, where he completed his bachelor's degree in 1973 and his doctoral degree in 1978. That year he accepted a position with IBM's Research Laboratory in Zurich, working with the physics research group.

Born in Buchs, Switzerland on June 6, 1933, Rohrer earned his bachelor’s degree in physics from the Swiss Federal Institute of Technology in Zurich in 1955 and his doctoral degree in 1960. He traveled to the United States to do post-doctoral research with Rutgers University and returned to Switzerland in 1963 where he also joined IBM’s Zurich lab.

There the men met and began working together. It would be more than a decade before their efforts would result in the powerful breakthrough in research technology that they have become famous for. The scanning tunneling microscope, or STM, has the power to form an image of individual atoms on a metal or semiconductor surface. The way it works is to scan the tip of a needle, or “probe,” just a few atomic diameters above the surface of the material. A voltage is applied between the tip of the probe and the surface, and as a current begins to flow between them, the STM can determine minute variations in the distance electrons travel and save this information in a data file. With this data the STM can produce an image of the electrical topography of the surface.

In this way, the STM can “see” atomic-scale objects up to 1/25th the diameter of a typical atom. By creating three-dimensional profiles of a surface, the device can help researchers in a variety of ways including determining size and form of molecules, observing defects and abnormalities on a surface, even discovering how chemicals interact with a material. The STM quickly became standard equipment in laboratories throughout the world, in fields as diverse as molecular biology, metallurgy, chemistry and semiconductor science.

For their work, Binnig and Rohrer were honored with numerous awards including the German Physics Prize, the Otto Klung Prize, and the Hewlett Packard Prize, the King Faisal Prize. In 1986, they were awarded the Nobel Prize in Physics along with German scientist Ernst Ruska, who designed the first electron microscope.

In 1985, Binnig relocated to IBM's Almaden Research Center in San Jose, California. There he and a team of researchers invented the atomic force microscope, which allows scientists to map non-electrically conducting surfaces as well. He was a visiting professor at Stanford University from 1987 to 1988 and appointed an IBM Fellow in 1987. He continues to work for IBM’s research arm.

Rohrer became an IBM Fellow in 1986 and managed the physical sciences department at the Zurich Research Laboratory from 1986 to 1988. He retired from IBM in July 1997.

[April 2004]