is the 52nd birthday of Gerd Binnig, a German physicist who, together with Heinrich Rohrer, invented the scanning tunneling microscope (STM), an instrument used to create atomic-level images of surfaces.
While working at the IBM Research Laboratory in Zurich, Switzerland, Binnig and Rohrer set out to develop a tool for studying the conductivity of surfaces, making use of the wavelike properties of electrons, which allow them to "tunnel" across a small gap between a surface and a probe. In 1981, the work led to the first scanning tunneling microscope, which images surface topography as well as conductivity. It uses a sharp tungsten probe only one angstrom wide positioned just a few angstroms above the sample surface. A small voltage between the tip and the surface causes electrons to tunnel across the gap. As the probe scans the sample, surface undulations cause variations in the tunneling current, which are recorded and used to produce an image. Their first STM image showed rows of evenly spaced atoms on a gold surface.
The invention, which won Binnig and Rohrer the Nobel Prize for Physics in 1986, opened up a whole new era in surface science.
[Source: Britannica Online]