A microscopic lightning rod allowed humans to image individual atoms
In 1981, IBM researchers Gerd Binnig and Heinrich Rohrer created the scanning tunneling microscope, unlocking the world of nanotechnology. The device sweeps a needle sharpened to a single atom just fractions of a nanometer above a surface. By exploiting quantum tunneling, where electrons leap across the empty gap, the microscope measures fluctuations in electrical current to trace the contours of individual atoms—rendering atomic surfaces visible for the first time.
The Search for the Atomic Frontier
For centuries, the fundamental limit of microscopy was dictated by the wavelength of light. Conventional optical microscopes cannot resolve features smaller than roughly half the wavelength of visible light—a threshold known as the diffraction limit, which stands at several hundred nanometers. Individual atoms, measuring merely tenths of a nanometer across, remained entirely beyond the reach of lens-based optics. Even transmission electron microscopes, which bypassed optical diffraction by focusing high-energy beams of electrons through thin specimens, struggled to provide direct, real-space three-dimensional topographies of atomic surface structures.
In the late 1970s, Gerd Binnig and Heinrich Rohrer at the IBM Zurich Research Laboratory in Switzerland sought a fundamentally different way to examine surfaces. Rather than focusing radiation through a lens, they proposed physically moving a probe across a material at sub-nanometer distances. Their work built upon earlier experiments, including Russell Young's Topografiner developed between 1965 and 1971 at the National Bureau of Standards, which had used field emission to scan surfaces. Binnig and Rohrer aimed to push much closer, entering a regime where quantum mechanical phenomena could act as an ultra-sensitive measuring stick.
By 1981, Binnig and Rohrer had constructed the first operational scanning tunneling microscope (STM). The instrument bypassed the diffraction limit entirely by abandoning wave optics in favor of a localized interaction between two conducting bodies. Five years later, in 1986, their invention earned them half of the Nobel Prize in Physics, an honor shared with Ernst Ruska, the pioneer of the electron microscope.