Ein Bild vom Atom

Materialwissenschaft erhält neues Spezial-Mikroskop

State: 18.07.2019 - 08:00 am

Imagine you could magnify a grain of sand with the naked eye so that it looks like a rock that completely fills the space between Jena and Erfurt and at 40 km altitude far exceeds Mount Everest. The new transmission electron microscope (TEM), which was recently installed at the Chair of Metallic Materials at the University of Jena, makes this simplistic. It is able to reach resolutions down to single atoms. Atomic diameter are on the order of approx. three ten-millionths of a millimeter (2 to 4 Å). "The new microscope achieves a resolution of 0.8 angstroms, which enables the direct imaging of almost all types of atoms," says Prof. Dr. med. Markus Rettenmayr.

The high resolution is achieved by a correction lens ("aberration corrector"), which compensates for the unavoidable aberration of the magnetic lenses that form the electron beam. The TEM, which has a value of over 3.5 million euros, is the only device in Thuringia that has such a corrector.

Complex high tech artwork

Since this high-tech work of art requires a long training period for the operators, it is mainly used by the Otto Schott Institute and the Institute of Solid State Physics of the University of Jena and their research partners. Currently u. a. Phase transformations examined. The properties of many alloys arise during manufacture by forming the microstructure, which is usually done by phase transformations. The most important phase transformation is the solidification from the melt, but even in festivals phase transformations still take place. "So far, little information has been gained on early stages of phase transformations, although much is already being decided," says Rettenmayr. "If there are several phases that can form, we would like to explore the reasons for which phase is the first," the materials expert says of a research project that is hoping for much of the new TEM.

20 tons concrete baseplate

The device has high electronic and mechanical stability and optimal conditions have been created at the Institute of Solid State Physics. The TEM stands on a 20-ton concrete baseplate, which is mechanically decoupled completely from the rest of the building and therefore stands completely free of vibrations. The TEM room is shielded from the outside world by 80 cm thick concrete walls. The device is controlled from a separate room; speak or - much worse - clap your hands would cause vibrations and blur the image for minutes.

"The outstanding strength of the device lies in the possibilities of precise chemical analysis," emphasizes Markus Rettenmayr. In addition to five imaging detectors, the device is equipped with two spectrometers for chemical analysis. These benefit immensely from the electron source ("cold field emitter"), which is characterized by a low energy width and a high directional radiation value. In the combination of modern electron source and modern detectors such a device has never been installed. "At the moment, the TEM in Jena is Europe's best in chemical analysis," says Prof. Rettenmayr.

The cost of the high-performance research equipment have worn the federal government, the state of Thuringia and the university.

Quelle: Uni Jena - News - A picture of the atom (18.07.2019, DE only)

Link: Chair of Metallic Materials

Picture: The new transmission electron microscope in the department of materials science.
Photo: Jan-Peter Kasper/ FSU