Inelastic scattering of 80 keV electrons in amorphous carbon

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Abstract
The cross-section for inelastic scattering of 80 keV electrons in thin films of evaporated carbon has been measured as a function of energy loss (from 10 to 600 eV) and scattering angle (up to 0·1 rad). The onergy-loss spectrum shows a broad peak around 24 eV, believed to arise mainly from plasmon oscillation of valence electrons. Losses between 50 and 280 eV are principally due to single interband transitions of the valence electrons, their intensity being proportional to (energy loss)−r , with r in the range 4 to 4·5. Their angular distribution shows a broad peak within the range 20—50 mrad (dependent on the energy loss) which can be explained using oither a wave-mechanical or a ballistic model. The cross-section for K-shell excitation (energy loss > 285 eV) was measured as a function of scattering angle; the results appear to be in good agreement with Bethe theory. Implications of inelastic scattering in transmission electron microscopy of carbon and organic materials are discussed with reforenco to chromatic aberration, beam divergence effects and the contribution to diffraction and Kikuchi patterns.