The invention allowed scientists entry into the atomic world in a way that had never been possible and was a major advance in the field of nanotechnology. For their remarkable achievement, Binnig and Rohrer shared the 1986 Nobel Prize in Physics with Ernst Ruska, inventor of the electron microscope. That same year Binnig developed the first atomic force microscope (AFM), further expanding the array of tools available to researchers seeking a better understanding of materials on an atomic scale.
Binnig entered the world on July 20, 1947, the elder of two sons born to Karl Franz Binnig and Ruth Bracke Binnig. As a child, he decided to become be physicist, though at the time he had very little understanding of what such an occupation would entail. In his later years, he sometimes questioned his decision, especially since he also had a keen interest in music. Fortunately for the advance of science, he earned both bachelor’s and doctoral degrees in physics at Johann Wolfgang Goethe University in Frankfurt and embarked on a successful career in the field, as he had planned in his youth. Binnig’s dissertation was a study of superconductivity, an area of interest he would later share with Rohrer.
While still a student, Binnig married Lore Wagler, with whom he would have two children. She convinced Binnig to accept a position as a researcher in physics at IBM following graduation. The young couple relocated to Zürich, a move that enabled Binnig to meet Rohrer. Working together in the research laboratory, Binnig and Rohrer found that they were interested in the same type of scientific pursuits. Both had backgrounds in superconductivity and developed a fascination with the study of surfaces. This topic is notoriously complex because of the distinct atomic characteristics of surfaces, which differ considerably from the interior of a material.
After considering all the tools available at the time, Binnig and Rohrer decided no existing instrument would allow them to adequately explore atomic surface imperfections. If they were to accomplish their goals, they would need themselves to build an instrument capable of visualizing individual atoms. How best to complete such a task took some time to determine, but the pair eventually began experimenting with electron tunneling, a quantum phenomenon characterized by the passage of electrons through barriers in a way that cannot be explained by classical physics. The approach proved successful, and they built the first scanning tunneling microscope.
The nonoptical device consists of a probe with an extremely fine tip that slowly scans over a sample at a constant distance. Electrons tunnel between the probe tip and the sample’s surface. Changes in the electric current result in vertical adjustments of the probe tip in order to maintain a constant signal and the fixed distance between the tip and the surface being examined. The variations are recorded and a computer generates a three-dimensional map of the sample’s surface. The measurements involved are on such a small scale that the map shows distinct atoms. To accurately produce measurements on such a miniscule scale, the components involved must be extremely small as well. The early version of the Binnig and Rohrer’s STM used a needle-like probe, which wasn’t fine enough to obtain the type of detail described above. They needed to make many improvements to the prototype, and eventually succeeded in building an STM with a probe tip approximately one atom wide maintained at a distance of approximately 5 to 10 angstroms from a sample’s surface.
The first atomic images that Binning and Rohrer produced were of the surface of gold; the invention was made public in 1981. At first the scientific community was unenthusiastic. But eventually refinements of the device and the increasingly clearer images it produced led to widespread recognition of its tremendous potential. Suddenly scientists had an instrument within their grasp that would allow them to carry out new kinds of research in physics, nanotechnology and chemistry. Although the device performs best when examining electrically conductive surfaces, researchers discovered it also did well with organic materials if they were affixed to a more suitable surface.
Not long after he received the Nobel Prize, Binnig announced the development of yet another type of microscope, which he dubbed the atomic force microscope. Like the STM, the AFM visualizes materials on an atomic scale. But rather than being based on electron tunneling, it makes use of the force that exists between atoms to move the tip of a scanning probe. This new type of microscopy eliminated the need for an electrically conductive sample or substrate altogether.
In 1984, Binnig became a research group leader at IBM and has since become a Fellow Emeritus at the company. He has also served as a visiting professor at Stanford University and wrote the book Aus dem Nichts (Out of Nothing), which was published in 1989 and explores how creativity is related to chaos. In 1994, Binnig co-founded with Dieter Herold an imaging company now known as Definiens AG.
