Heinrich Rohrer Biography (1933-)


Heinrich Rohrer was born in 1933, in Buchs, St. Gallen, Switzerland, the sonof Hans Heinrich Rohrer, a distributor of manufactured goods, and Katharina Ganpenbein Rohrer. He received his Ph.D. in physics in from the Federal Institute of Technology in Zurich. His doctoral research involved superconductivity.

In 1963, Rohrer joined the staff of the research laboratory of InternationalBusiness Machines (IBM) in Zurich, eventually becoming manager of the physicsdepartment as well as an IBM Fellow. Rohrer has remained at the IBM lab throughout his career. In 1961, Rohrer married Rose-Marie Eggar; the couple had two daughters.

After joining IBM, Rohrer expanded his research in physics beyond superconductivity, investigating magnetic fields and critical phenomena. He became interested in the little-understood and complex atomic structures of the surfacesof materials. While electron microscopes had been developed to probe the internal arrangements of atoms in materials, attempts to uncover the very different characteristics of surface atoms had been decidedly unsuccessful. In 1978Gerd Binnig, a young German who had just received his Ph.D., joined Rohrer'sresearch team in Zurich. Together, Rohrer and Binnig began to explore oxide layers on metal surfaces. They decided to develop a spectroscopic probe and inthe process invented an entirely new type of microscope, the scanning tunneling microscope (STM).

Rohrer and Binnig began with the phenomenon called tunneling. As revealed through quantum mechanics, electrons behave in a wavelike manner that causes them to produce a diffuse cloud as they leak out from the surface of a sample. When electron clouds from two adjacent surfaces overlap, electrons tunnel fromone surface or cloud to the other. Tunneling through an insulating layer hadbeen used often to reveal information about the materials on either side ofthe insulation. Rohrer and Binnig decided to tunnel through a vacuum and thenuse a sharp, needlelike probe within the vacuum to scan the sample's surface. As the scanning tip closely approached the sample, the electron clouds of each overlapped and a tunneling current began to flow. A feedback mechanism used the tunneling current to keep the tip at a constant height above the sample's surface. In this way, the tip followed the contours of the individual atoms of the scanned surface, and a computer processed the tip's motion to produce a three-dimensional, high-resolution image of that surface.

One large problem was the sensitivity of the scanning tip to disturbances from vibration and noise. Here Rohrer's background in superconductors was helpful, because transducers too are extremely sensitive to vibration. Rohrer and Binnig solved the problem by shielding their scanner from disturbances with magnets and a heavy stone table set on inflated rubber tires. They successfullytested their new device in 1981 and then worked to refine it technologically. By the mid-1980s the STM could fit in the palm of the and could show some details as tiny as 0.1 angstrom (with 1 angstrom being about the diameter of asingle atom, or 2.5 billionths of an inch). STMs were also developed that worked in water, air, and cryogenic fluids as well as vacuums. By 1987 Rohrer'sgroup at IBM had developed an STM the size of a fingertip.

Rohrer and Binnig shared the Nobel Prize in 1986 for their STM, which openedup entirely new fields for the study of the structure of matter. Rohrer shared other international awards with Binnig for his work on the STM. He is a member of many important scientific societies and has been awarded honorary doctorates by several universities. In 1997 Rohrer retired from IBM.

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