The Theory of Normal and Abnormal Absorptions in Electron Diffraction

A theory of normal and abnormal absorptions in electron diffraction is presented on the basis of the calculation of the transition probability. The normal and abnormal absorption coefficients are shown to be expressible in terms of the so-called “energy-loss function”, or Im -1/η(ω), where η(ω) is the complex dielectric constant for the crystal. The values µ 0 , the normal absorption coefficient, and Δ µ h , the abnormal absorption coefficient, are calculated numerically for Si at 50 keV, 67 keV and 100 keV of incident electrons, and the results are compared with experimental data.