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Distribution and Behaviour of Positive Ions in the Environmental Scanning Electron Microscope (ESEM)

Published online by Cambridge University Press:  02 July 2020

John P. Craven ,
Frank S. Baker  and
Bradley L. Thiel
John P. Craven
Affiliation:
Polymers & Colloids, Dept. of Physics, University of Cambridge, Cavendish Laboratory, Cambridge. U.K.CB3 OHE.
Frank S. Baker
Affiliation:
Polymers & Colloids, Dept. of Physics, University of Cambridge, Cavendish Laboratory, Cambridge. U.K.CB3 OHE.
Bradley L. Thiel
Affiliation:
Polymers & Colloids, Dept. of Physics, University of Cambridge, Cavendish Laboratory, Cambridge. U.K.CB3 OHE.
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Extract

Electron detection in the environmental scanning electron microscope relies upon the presence of a small pressure of a gaseous phase inside the microscope chamber. The presence of this gas controls two important mechanisms by which the microscope functions. The conventional gaseous secondary electron detector (GSED) applies a variable positive bias (0 to +600 V) directly above the specimen. Electrons ejected from the specimen surface due to the incident scanning probe are accelerated by this field towards the positively biased detector. Whilst traversing the gap between specimen and detector the electrons undergo ionizing collisions with gas molecules. These result in an amplification of the incident electron signal through the production of ejected ‘daughter’ electrons and leave behind positively charged ions. After production these ions are repelled by the detector bias and drift back towards the microscope stage where they aid charge neutralization on the surface of the specimen.

Type
Working with ESEM and Other Variable Pressure Systems
Information
Microscopy and Microanalysis , Volume 6 , Issue S2: Proceedings: Microscopy & Microanalysis 2000, Microscopy Society of America 58th Annual Meeting, Microbeam Analysis Society 34th Annual Meeting, Microscopical Society of Canada/Societe de Microscopie de Canada 27th Annual Meeting, Philadelphia, Pennsylvania August 13-17, 2000 , August 2000 , pp. 776 - 777
Copyright
Copyright © Microscopy Society of America

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References

References:

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[4] This work was funded by the Engineering and Physical Science Research Council (EPSRC) and Schlumberger Cambridge Research (SCR), Cambridge, UK.Google Scholar