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Using Secondary Electron Contrast for Imaging Water-Oil Emulsions in the Environmental SEM (ESEM)

Published online by Cambridge University Press:  02 July 2020

D.J. Stokes ,
B.L. Thiel  and
A.M. Donald
D.J. Stokes
Affiliation:
Department of Physics, University of Cambridge, Cavendish Laboratory, Madingley Road, Cambridge, CB3 0HE, England, UK
B.L. Thiel
Affiliation:
Department of Physics, University of Cambridge, Cavendish Laboratory, Madingley Road, Cambridge, CB3 0HE, England, UK
A.M. Donald
Affiliation:
Department of Physics, University of Cambridge, Cavendish Laboratory, Madingley Road, Cambridge, CB3 0HE, England, UK
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Extract

The ESEM is able to image liquids in their natural state, unlike conventional SEM, and offers significantly better resolution than optical microscopy. The ability to image binary liquid mixtures, such as water-oil emulsions, depends upon sufficient contrast for differentiation of the dispersed and continuous phases. We have made observations of such water-oil emulsions in an Electroscan 2010 Environmental SEM, and have duly obtained images with good contrast. Experiments were carried out on emulsions of vegetable oil-in-water, polybutene-in-water and water-in-polybutene, all emulsified with nonionic polysaccharide surfactants. Each sample was imaged at a temperature of approximately 3°C, in water vapour at a pressure of 4 torr, in order to maintain the liquid state.

From the ESEM micrographs in Figures 1, 2 and 3, it is clear that water exhibits a greater secondary electron emission than an unsaturated hydrocarbon.

Type
New Trends in Scanning Electron Microscopy and Microanalysis
Information
Microscopy and Microanalysis , Volume 4 , Issue S2: Proceedings: Microscopy & Microanalysis '98, Microscopy Society of America 56th Annual Meeting, Microbeam Analysis Society 32nd Annual Meeting, Atlanta, Georgia July 12-16, 1998 , July 1998 , pp. 300 - 301
Copyright
Copyright © Microscopy Society of America

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References

1.Cameron, R.E. & Donald, A.M., J. Microscopy, 173, pt.3, 1994, 227–237.CrossRefGoogle Scholar
2.Thiel, B.L., Stokes, D.J. & Donald, A.M., elsewhere in these procedings.Google Scholar
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5. This work is funded by Dalgety and the BBSRC.Google Scholar