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Stem Without Spherical Aberration

Published online by Cambridge University Press:  02 July 2020

O.L. Krivanek
Affiliation:
also at:, Dept. of Materials Science and Engineering, U. of Washington, Seattle, WA98195, USA
N. Dellby
Affiliation:
Nion Co., 1102 8th St., Kirkland, WA98033, USA
A.R. Lupini
Affiliation:
Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge, CB3 OHE, UK
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Extract

Even though two generations of electron microscopists have come to accept that the resolution of their instruments is limited by spherical aberration, three different aberration correctors showing that the aberration can be overcome have recently been built [1-3]. One of these correctors was developed by us specifically for forming small electron probes in a dedicated scanning transmission electron microscope (STEM) [3, 4]. It promises to revolutionize the way STEM instruments are built and the types of problems that they are applied to.

As was the case with the Berlin Wall, when a barrier that was once thought immovable finally crumbles, many of the consequences can be quite unexpected. For STEM, the removal of spherical aberration (Cs) as the main resolution limit is likely to lead to a new paradigm in which:

1) The resolution at a given operating voltage will improve by about 3x relative to today's best. When Cs can be adjusted arbitrarily in a STEM being used for microanalysis or dark field imaging, defocus and Cs are set to values that optimally oppose the effect of the 5th-order spherical aberration C5.

Type
A. Howie Symposium: Celebration of Pioneering Electron Microscopy
Copyright
Copyright © Microscopy Society of America

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References

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