The 1986 Nobel Prize in Chemistry was awarded to Ernst Ruska for his pioneering work in designing the first electron microscope, and to Gerd Binnig and Heinrich Rohrer for the invention of the scanning tunneling microscope (STM). These technological breakthroughs revolutionized science's ability to observe the world at the atomic scale, opening new avenues in materials research and surface physics. Ruska, in particular, laid the groundwork for transmission electron microscopy (TEM), an indispensable tool today for visualizing internal material structures with unprecedented resolution.

Ruska's electron microscope, developed in the 1930s, overcame the diffraction limits of visible light by using electron beams, whose wavelength is much smaller. This allowed for resolutions that made atom-sized objects visible, something unthinkable with conventional optical microscopes. Binnig and Rohrer, in the 1980s, took resolution a step further with the STM, which not only visualizes individual atoms on a surface but can also manipulate them, opening the doors to nanotechnology and atomic-scale engineering.

The invention of the STM is based on the quantum tunneling effect, where electrons can cross a seemingly impenetrable potential barrier between a sharp conductive tip and a surface. By maintaining an extremely small distance and applying a voltage, a tunneling current is generated that is incredibly sensitive to the distance. By scanning the tip over the surface and keeping the tunneling current constant, the atomic topography of the surface can be mapped with astonishing precision. These microscopes have not only allowed for the observation of atomic structure but have also been fundamental to understanding the electronic and magnetic properties of materials at the nanoscale, driving the development of new devices and materials with tailored properties.