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January 22, 2008

0.5 Angstrom transmission electron microscope

TEAM 0.5 (Transmission electron achromatic microscope), the world's most powerful transmission electron microscope — capable of producing images with half‑angstrom resolution (half a ten-billionth of a meter), less than the diameter of a single hydrogen atom — has been installed at the Department of Energy's National Center for Electron Microscopy (NCEM) at Lawrence Berkeley National Laboratory.

This is continued testing and operational installation from Sept 2007 when it was tested before being sent to the lab

Correcting spherical aberration makes it possible to use the TEAM 0.5 not only for broad-beam, "wide-angle" images but also for scanning transmission electron microscopy (STEM),
in which the tightly focused electron beam is moved across the sample as a probe, capable of performing spectroscopy on one atom at a time — an ideal way to precisely locate impurities in an otherwise homogeneous sample, such as individual dopant atoms in a semiconductor material.

Aberration correction is also essential for another advanced feature of TEAM 0.5: its ability to maintain high resolution with lower electron beam energies.




TEAM 0.5, the world's best transmission electron microscope, is being assembled at the National Center for Electron Microscopy. (Photo Roy Kaltschmidt, Berkeley Lab CSO)

Installation of the new stage must await the next phase of the TEAM Project: the TEAM I microscope, due to be set up at NCEM early in 2009.

While TEAM 0.5 corrects spherical aberration in both the "probe" beam (the electron beam before it strikes the sample) and the image beam (after it exits the sample, but before it reaches the detector), TEAM I will also correct chromatic aberration in the image beam, which has never beeen accomplished before. Spherical aberration is caused by the shape of a lens; chromatic aberration results when a lens refracts light or electrons of different wavelengths (different colors or energies) at different angles.




FURTHER READING
The TEAM project

Part of a 20 year roadmap for improving science facilities in the USA

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