Electron beam current loss at the high-vacuum-high-pressure boundary in the environmental scanning electron microscope

Danilatos, Gerasimos D., Phillips, Matthew R. and Nailon, John V. (2001) Electron beam current loss at the high-vacuum-high-pressure boundary in the environmental scanning electron microscope. Microscopy And Microanalysis, 7 5: 397-406.


Author Danilatos, Gerasimos D.
Phillips, Matthew R.
Nailon, John V.
Title Electron beam current loss at the high-vacuum-high-pressure boundary in the environmental scanning electron microscope
Journal name Microscopy And Microanalysis   Check publisher's open access policy
ISSN 1435-8115
1431-9276
Publication date 2001-09
Sub-type Article (original research)
Volume 7
Issue 5
Start page 397
End page 406
Total pages 12
Place of publication New York, N.Y. U.S.A.
Publisher Springer-Verlag
Collection year 2001
Language eng
Subject C1
299904 Engineering/Technology Instrumentation
671401 Scientific instrumentation
Abstract A significant loss in electron probe current can occur before the electron beam enters the specimen chamber of an environmental scanning electron microscope (ESEM). This loss results from electron scattering in a gaseous jet formed inside and downstream (above) the pressure-limiting aperture (PLA), which separates the high-pressure and high-vacuum regions of the microscope. The electron beam loss above the PLA has been calculated for three different ESEMs, each with a different PLA geometry: an ElectroScan E3, a Philips XL30 ESEM, and a prototype instrument. The mass thickness of gas above the PLA in each case has been determined by Monte Carlo simulation of the gas density variation in the gas jet. It has been found that the PLA configurations used in the commercial instruments produce considerable loss in the electron probe current that dramatically degrades their performance at high chamber pressure and low accelerating voltage. These detrimental effects are minimized in the prototype instrument, which has an optimized thin-foil PLA design.
Keyword Microscopy
Environmental Scanning Electron Microscope
Electron Scattering
Electron Loss
Differential Pumping
Gas Jet
Pressure Limiting Aperture
Image Noise
Electron Skirt
Construction
Design
Sem
Q-Index Code C1

Document type: Journal Article
Sub-type: Article (original research)
Collection: Centre for Microscopy and Microanalysis Publications
 
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Created: Tue, 14 Aug 2007, 14:55:48 EST