Contamination formed around a very narrow electron beam.

Area of Science:

• Materials Science
• Microscopy
• Surface Science

Background:

• Specimen contamination is a common issue in electron microscopy.
• Understanding contamination deposition processes is crucial for accurate analysis.
• Previous studies have not fully elucidated the mechanisms of contamination growth.

Purpose of the Study:

• To investigate the mechanisms of specimen contamination in electron microscopy.
• To quantify the growth rates of contamination features.
• To identify the sources and transport of contaminating material.

Main Methods:

• Utilized a narrow electron beam to create localized contamination peaks on a thin carbon film.
• Imaged contamination peaks to determine growth rates of height, diameter, and volume.
• Investigated material deposition in both irradiated and non-irradiated regions.

Main Results:

• Quantified the growth rates of contamination peaks.
• Established a link between electron beam interaction and surface contamination.
• Observed significant contamination deposition in areas not directly exposed to the electron beam.
• Developed a method for determining the thickness of thin amorphous carbon films.

Conclusions:

• Electron beam interaction with adsorbed surface layers contributes to contamination.
• Surface migration of adsorbed material is a key supply mechanism for contamination.
• Un-irradiated areas can accumulate significant contamination, a novel finding.
• The described method allows for accurate thickness determination of carbon films.