It may be hard to believe but the first electron microscope was developed by German physicist Hans Busch in 1926 with a prototype built by Ernst Ruska and the electrical engineer Max Knoll in 1931. In 1933 Ruska built an electron microscope (or EM) that surpassed the resolution which could be achieved with a light microscope. Yet perhaps even Ruska could not have envisioned future developments, which mean that today we can see things such as the zinc oxide particle (above) in more detail than ever before.
The difference between an EM and the microscope of old is fairly straightforward even if the science which separates them is not. An EM uses an electron beam to illuminate a specimen rather than light. As such is can make out tiny details of a given object with a significantly greater
resolving power than a light microscope. The detail is greater because the wavelength is shorter: visible light photons are about 100,000 times longer than those of electrons in terms of wavelength. The picture above shows the aftermath of fayalite reacting with gaseous CO2 to form siderite, thereby capturing the CO2 in a solid, stable form
