Graphene specimen support technique for low voltage STEM imaging

Electron microscopes relies on an electron beam rather

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than light to illuminate the target sample. The electron beam would hit the sample, with the resulting scattering of the electrons allowing scientists to build an accurate image of the target. This way, electron microscopes can achieve a much higher resolution compared to light-based devices. Prof. Shintake's unique microscope does not even rely on optical lenses any longer, instead using a detector to reveal which electrons hit the tiny virus samples and reconstructing the image through a computer algorithm. Moreover, while conventional electron microscopes require high-energy electrons, this microscope rather focuses on low-energy electrons which can potentially be much more efficient at imaging viruses if the associated technical issues can be overcome.

"Low-energy electrons interacts very strongly with matter," explained Dr. Masao Yamashita, the first author of the study. "They are great for imaging biological specimens, made up of light materials like carbon, oxygen and nitrogen, which are basically transparent to high energy electrons."

Using low energy electrons however has an important drawback: because of its high sensitivity with matter, a low energy electron beam would interact with the target sample but also with everything else like the support plate and film on which the sample is laying. The resulting image would not distinguish the study material from the background.

Read more at: https://phys.org/news/2017-06-graphene-specimen-technique-voltage-stem.html#jCp