Three decades of scanning tunnelling microscopy that changed the course of surface science

Using theSTM, Binnig became the first person to observe a virus escape from a living cell. The tremendous importance of the STM lies in its many applications–forbasic research in chemistry, physics, and biology and for applied research insemiconductor physics, microelectronics, metallurgy, and bioengineering. Immediately after his PhD he moved to Zürich, where he became a research staff member at IBM. In collaboration with Heinrich Rohrer and other colleagues including Christoph Gerber and Edmund Weibel, in 1981 he developed the scanning tunnelling microscope.

They shared the award with German scientist Ernst Ruska, the designer of the first electron microscope. Several scanning microscopies use the scanning technology developed for the STM.

A similar microscope called the Topografiner was invented by Russell Young and his colleagues between 1965 and 1971 at the National Bureau of Standards, currently known as the National Institute of Standards and Technology. This microscope works on the principle that the left and right piezo drivers scan the tip over and slightly above the specimen surface. The center piezo is controlled by a servo system to maintain a constant voltage, which results in a consistent vertical separation between the tip and the surface. An electron multiplier detects the tiny fraction of the tunneling current which is scattered by the specimen surface.

As shown, a laser is reflected from the back of a cantilever that includes the AFM tip. As the tip interacts with the surface, the laser position on the photodetector is used in the feedback loop to track the surface for imaging and measuring.

It provides a three-dimensional profile of the surface which is very useful for characterizing surface roughness, observing surface defects, and determining the size and conformation of molecules and aggregates on the surface. In order to insulate their microscope against the serious problem of distorting vibration and noise, Binnig and Rohrer made a series of technical advances that included the creation of a probe tip consisting of a single atom. The colleagues and their research team soon demonstrated practical uses of the STM, revealing the surface structure of crystals, observing chemical interactions, and scanning the surface of DNA (deoxyribonucleic acid) chains. Using the STM, Binnig became the first person to observe a virus escape from a living cell.

From 1987-1995 he directed an IBM physics research group at the Ludwig Maximilian University in Munich, earning a Honorary Professorship in 1987. He then returned to Zurich, where he continues to work for the IBM corporation as a research scientist.

Is it the case that this lack of criticism during 1982-1985, which was complemented with amazing surface images, was the defining contributing factor to Binnig and Rohrer’s ability to gain success in such a short span of time? Could we correlate the lack of criticism of the instrument and thus the non-improvement of the instrument during 1982-1985 with overlooking possible instrumental errors? This issue should be seen within a comprehensive historical-philosophical research devoted to the role of error in STM both on the instrumental level and in the production of images, and generally in enhancement techniques for amplifying and displaying data electronically.

It also stimulated an interest in creativity on his part, and his recent theoretical interests have turned toward explaining the nature of creativity and developing technologies that mimic human thought. Binnig realized that the process through which he and Rohrer invented the STM could not be explained through extant theoretical models of how creativity functions. Binnig now argues that creativity works according to a model he calls “fractal Darwinism,” in which new ideas are generated by moving between different scales of analysis in order to solve specific problems.

To accomplish their goal, Binnig and Rohrer turned to a phenomenon of quantummechanics known as tunneling. Quantum mechanics had earlier revealed that the wavelike nature of electrons permits them to escape the surface boundary ofa solid–they “smear out” beyond the surface and form an electron cloud around the solid.

They could be the beginning of a new era in surface science. The new players in the emerging nano-world are individual, selected objects of the size of some 50 nm down to molecules and atoms. The new aspect of science and technology on the nanometer scale is that these objects are treated as individuals, not as ensemble members.

Disorder arises from locally random sequences of the two facets. We present scanning tunneling microscopy images for bare and shadowed recA-DNA complexes prepared on graphite substrates.

heinrich rohrer and gerd binnig 1985

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November 3, 2009

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