The origin of specimen contamination in the electron microscope

Ennos, A. E.

doi:10.1088/0508-3443/4/4/302

Cited by 217 publications

(75 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The increase in the rate constant with current is not linear but rolls off. A similar shaped curve has been reported by Ennos (Ennos, 1953). At higher currents the trend reverses and the contamination rate begins to fall with further increases in current.…”

Section: The Kinetics Of Depositionsupporting

confidence: 86%

“…Extended exposure of the thin carbon film to a static probe leads to erosion and eventually a hole is created in the carbon support film. Increasing the electron flux may enhance both hydrocarbon diffusion and cracking rates (Ennos, 1953). However, at higher electron fluxes, new processes come into play.…”

Section: The Kinetics Of Depositionmentioning

confidence: 99%

“…By raising the temperature of the specimen in vacuo to 110°C, any species with a significant vapour pressure at this temperature should be desorbed (Ennos, 1953;McGilvery et al, 2012). This would include water and light organic fractions such as solvent residue.…”

Section: The Effect Of Bakingmentioning

confidence: 99%

“…Vacuum systems using oil-based rotary and diffusion pumps can produce back-streaming of oil. This oil vapour can then crack under the electron beam, resulting in the build-up of carbon on the area under investigation (Ennos, 1953). Improvements in pump oils and vacuum technology in general, have greatly diminished the contribution of the vacuum system to the contamination problem.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Contamination mitigation strategies for scanning transmission electron microscopy

Mitchell

2015

Micron

View full text Add to dashboard Cite

Modern scanning transmission electron microscopy (STEM) enables imaging and microanalysis at very high magnification. In the case of aberration-corrected STEM, atomic resolution is readily achieved. However, the electron fluxes used may be up to three orders of magnitude greater than those typically employed in conventional STEM. Since specimen contamination often increases with electron flux, specimen cleanliness is a critical factor in obtaining meaningful data when carrying out high magnification STEM. A range of different specimen cleaning methods have been applied to a variety of specimen types. The contamination rate has been measured quantitatively to assess the effectiveness of cleaning. The methods studied include: baking, cooling, plasma cleaning, beam showering and UV/ozone exposure. Of the methods tested, beam showering is rapid, experimentally convenient and very effective on a wide range of specimens. Oxidative plasma cleaning is also very effective and can be applied to specimens on carbon support films, albeit with some care. For electron beam-sensitive materials, cooling may be the method of choice. In most cases, preliminary removal of the bulk of the contamination by methods such as baking or plasma cleaning, followed by beam showering, where necessary, can result in a contamination-free specimen suitable for extended atomic scale imaging and analysis. Modern scanning transmission electron microscopy (STEM) enables imaging and microanalysis at very high magnification. In the case of aberration-corrected STEM, atomic resolution is readily achieved. However, the electron fluxes used may be up to three orders of magnitude greater than those typically employed in conventional STEM. Since specimen contamination often increases with electron flux, specimen cleanliness is a critical factor in obtaining meaningful data when carrying out high magnification STEM. A range of different specimen cleaning methods have been applied to a variety of specimen types. The contamination rate has been measured quantitatively to assess the effectiveness of cleaning. The methods studied include: baking, cooling, plasma cleaning, beam showering and UV/ozone exposure. Of the methods tested, beam showering is rapid, experimentally convenient and very effective on a wide range of specimens. Oxidative plasma cleaning is also very effective and can be applied to specimens on carbon support films, albeit with some care. For electron beam-sensitive materials, cooling may be the method of choice. In most cases, preliminary removal of the bulk of the contamination by methods such as baking or plasma cleaning, followed by beam showering, where necessary, can result in a contamination-free specimen suitable for extended atomic scale imaging and analysis.

show abstract

Section: The Kinetics Of Depositionsupporting

confidence: 86%

Section: The Kinetics Of Depositionmentioning

confidence: 99%

Section: The Effect Of Bakingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Contamination mitigation strategies for scanning transmission electron microscopy

Mitchell

2015

Micron

View full text Add to dashboard Cite

show abstract

“…The main impurities in the metal were C, N, O, Al, Si and Fe. C, N and O impurities were considered as over-estimated owing to (a) carbon deposition from residual hydrocarbon disintegration by the action of the electron beam and (b) the ubiquitous presence of a surface oxide film, and (c) amplification of the signal coming from the low mass elements (over the heavy elements), for low accelerating voltages [33][34][35]. Preliminary scanning electron microscopy (SEM) inspection of the surface revealed carbides and carbo-nitrides of varied morphology.…”

Section: Sample Characterisationmentioning

confidence: 99%

The effect of work-hardening and thermal annealing on the early stages of the uranium-hydrogen corrosion reaction

2018

View full text Add to dashboard Cite

A B S T R A C TThe characteristics of hydride formation on metallic U at the early stages were investigated for three differently treated samples. The first sample reacted in its as-received state, the second was thermally annealed and the third sample underwent cold work-hardening prior to reaction with deuterium. From the analysis, the vacuum heat-treated sample was found to be more resilient to hydriding at the nucleation and growth stage, exhibiting a reduced number of nucleation points when compared to the as-cast uranium. The work-hardened sample was observed to be more susceptible to H 2 corrosion, displaying very dissimilar hydriding behaviour when compared to the other.

show abstract

Polishing and Shaping of Monocrystalline Diamond

Hird

2013

Optical Engineering of Diamond

View full text Add to dashboard Cite

The origin of specimen contamination in the electron microscope

Cited by 217 publications

References 16 publications

Contamination mitigation strategies for scanning transmission electron microscopy

Contamination mitigation strategies for scanning transmission electron microscopy

The effect of work-hardening and thermal annealing on the early stages of the uranium-hydrogen corrosion reaction

Polishing and Shaping of Monocrystalline Diamond

Contact Info

Product

Resources

About