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Asbestos is a toxic substance that is found in older buildings, as well as in cosmetics and products for children. As testing for its presence can be problematic, Hiroshima University Professor Akio Kuroda has been working ...

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During the first COVID-19 wave, when Saumitra Das and colleagues were sequencing thousands of samples every day to check for SARS-CoV-2 variants as part of INSACOG, the Government of India's genome surveillance initiative, ...

Dying stars could seed interstellar medium with carbon nanotubes

Evidence suggests that carbon nanotubes, tiny tubes consisting of pure carbon, could be forged in the envelopes of dust and gas surrounding dying stars. The findings propose a simple, yet elegant mechanism for the formation ...

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Transmission electron microscopy

Transmission electron microscopy (TEM) is a microscopy technique whereby a beam of electrons is transmitted through an ultra thin specimen, interacting with the specimen as it passes through. An image is formed from the interaction of the electrons transmitted through the specimen; the image is magnified and focused onto an imaging device, such as a fluorescent screen, on a layer of photographic film, or to be detected by a sensor such as a CCD camera.

TEMs are capable of imaging at a significantly higher resolution than light microscopes, owing to the small de Broglie wavelength of electrons. This enables the instrument to be able to examine fine detail—even as small as a single column of atoms, which is tens of thousands times smaller than the smallest resolvable object in a light microscope. TEM forms a major analysis method in a range of scientific fields, in both physical and biological sciences. TEMs find application in cancer research, virology, materials science as well as pollution and semiconductor research.

At smaller magnifications TEM image contrast is due to absorption of electrons in the material, due to the thickness and composition of the material. At higher magnifications complex wave interactions modulate the intensity of the image, requiring expert analysis of observed images. Alternate modes of use allow for the TEM to observe modulations in chemical identity, crystal orientation, electronic structure and sample induced electron phase shift as well as the regular absorption based imaging.

The first TEM was built by Max Knoll and Ernst Ruska in 1931, with this group developing the first TEM with resolving power greater than that of light in 1933 and the first commercial TEM in 1939.

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