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Abstract:
Specimen contamination in the electron microscope is studied in an attempt to clarify the processes involved in contamination deposition. A very narrow electron beam has been used to make small peaks of contamination on the surface of a thin carbon film. These peaks have been imaged and the rates of growth of the height, diameter and volume determined. It is concluded that a portion of the contamination can be related to the interaction of the electron beam with the adsorbed surface layer. Surface migration of adsorbed material is indicated as the supply mechanism. Significant deposition of material in regions not exposed to the beam is reported for the first time. A method for determining the thickness of thin amorphous carbon film in the range of a hundred to a few thousand Angströms is described.