INELASTIC ELECTRON SCATTERING IN CARBON AND CARBONACEIUS MATERIALS AND CHROMATIC ABERRATION IN ELECTRON MICROSCOPY

An assessment is given of the effect of inelastic electron scattering on the resolution of an electron microscope image. The calculations are primarily concerned with inelastic electron scattering in thin films of carbon, which is of interest from the biological point of view. It is shown that the energy loss distribution of electrons (incident energies in the range 20-100kev) scattered in carbon and carbonaceous materials (e.g. Formvar, polystyrene) obtained for an objective semi-angular aperture, α, may be predicted within a standard deviation of about 5%, for energy losses less than 100 ev. A detailed knowledge of the energy loss distribution of electrons scattered in organic and biological materials leads to the possibility of correcting an electron micrograph for chromatic aberration effects caused by inelastic electron scattering in the specimen.