Heinrich (“Heini”) Rohrer, a nanotechnology pioneer, Nobel Prize winner, and personal mentor to me and many other scientists, has died. D. A. Bonnell & B. D. Huey (2001). “Basic principles of scanning probe microscopy”.
More recently, even more powerful microscopes have been developed that use the same basic scanning technology first developed for the STM. Gerd Binnig is a physicist at IBM’s Zurich Research Laboratory.
What can we learn from the above preference on the way the scientific community reacts towards a novel technology? During the years 1982-1984 Binnig and Rohrer had the priority and exclusiveness of the STM in the market, both in terms of theory and material culture and they therefore did not bother to improve the instrument. They concentrated rather on the images, which indeed made the whole affair so exciting, and on convincing demonstrations, with which no other existing surface-science tool could then compete. We find that during 1982-1984 there is no prominent criticism of the instrument, and in this case it is not science in the making, but a “closed shop” of believers impressed by flashy STM images. I got to know Heini in early 1985 when I started work at IBM’s main research center at Yorktown Heights, NY. Heini was on another continent, at IBM-Ruschlikon (Switzerland) but visited my IBM-Yorktown location often.
We report here that scanning tunnelling electron microscopy can be used to determine the surface topography of biological specimens at atmospheric pressure and room temperature, giving a vertical resolution of the order of 1 A. Our results show that quantum mechanical tunnelling of electrons through biological material is possible provided that the specimen is deposited on a conducting surface.
We report details of the array fabrication, the x-y scanning and approach system as well as images taken with the system. The results are encouraging for the development of large-scale VLSI-Nano EMS, allowing the fabrication and operation of large AFM cantilever arrays to achieve high-data-rate Terabit storage systems. Atomic Force Microscopy has a feedback loop using the laser deflection to control the force and tip position.
Thus, in the constant-current mode, the STM monitors wave-function overlap contours rather than the corrugation of atomic positions on the surface. The (0001) surface of graphite has been investigated using the scanning tunneling microscope (STM) over a relatively wide area containing many unit cells. We do not observe trigonal symmetry but rather find one preferred direction which remains unaffected even by extended defect areas.
Now he and Rohrer decided to make electrons tunnel through a vacuum from a sample solid surface to a sharp, needlelike probe. As theneedle tip approaches within a nanometer (one billionth of a meter) of the sample, their electron clouds touch and a tunneling current starts to flow. Theprobe’s tip follows this current at a constant height above the surface atoms, producing a three-dimensional map of the solid’s surface, atom by atom.
They play a central role for science and technology on the nanometer scale and will allow us to build systems of the same complexity as used by nature, which has built life on nanofunctionality. The development of the family of scanning probe microscopes started with the original invention of the STM in 1981. Gerd Binnig and Heinrich Rohrer developed the first working STM while working at IBM Zurich Research Laboratories in Switzerland. This instrument would later win Binnig and Rohrer the Nobel prize in physics in 1986. The scanning tunneling microscope is used to obtain atomic-scale images of metal surfaces.
A lateral resolution of better than 2 Å was achieved. The experiments further confirm directly the atomic flatness of some thousand ångstrom size areas of cleaved graphite.
Lead adsorption is accompanied by displacement of steps and smoothing of sub-nm corrugations, as well as by a steeper decay of the tunneling current with tip-substrate separation. Along certain parts of the substrate, repetitive Pb phase deposition/dissolution leads to formation of pronounced nm-scale steps on the Ag substrate. A short overview of the history of scanning tunneling microscopy and the principle of local probe methods is given. A selection of applications illustrates the unique and attractive features and the wide interdisciplinary nature of local probe methods.
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.