Heinrich Rohrer, a Swiss physicist and one of the two Nobel Prize-winning scientists who helped make possible the modern field of nanotechnology by inventing a microscope that could readily see individual atoms, died May 16. He was 79.
The Swiss newspaper Tages-Anzeiger reported that he died at his home in Wollerau, Switzerland. The cause of death was not disclosed.
The device Rohrer created at an IBM laboratory in 1981 with Gerd Binnig was called the scanning tunneling microscope, and they shared half of the physics Nobel in 1986. (German scientist Ernst Ruska also received a physics prize that year for unrelated work on the electron microscope.)
The device became a pillar of nanotechnology, the manipulation of individual atoms and molecules to create useful devices. Nanotechnology deals with dimensions on the order of a few millionths of an inch. Objects that size cannot be seen with the most powerful optical microscope.
But quantum mechanics, the theory of matter on the atomic scale, helped point a way forward for Rohrer and his colleagues. In quantum theory, electrons have wavelengths, which are smaller than those of visible light. Thus, microscopes using electron beams rather than beams of light can see smaller objects.
The devices stemming from Rohrer's work are even more powerful than the basic electron microscope. In part, they depend on a particularly startling feature of quantum reality: quantum tunneling.
In the quantum world, electrons can be in two places at once; they can show up on both sides of a seemingly impenetrable barrier. This phenomenon comes about through what is known as quantum tunneling, and the scanning tunneling microscope depends on it.
In the device, a probe with a tip as fine as a single atom moves over the surface of a material. Electrons tunnel through the minuscule gap between probe and surface. The current produced in this way varies with the distance between the probe and the surface.
High points on a surface, closer to the probe, create stronger current. For low points, the current is weaker. Charting the current yields a map of the surface.
Rohrer and his co-inventor produced an image suggesting a landscape of hills and valleys. But, they wrote, they recognized this image for what it was. They knew that the "pronounced and regularly arranged protrusions we saw" were actually individual atoms.
They had been told that such a precise finding was impossible.
"Rumors reached us that scientists would bet cases of champagne that our results were mere computer simulations!" they wrote. But their success soon became clear.