Effect of Inelastic Waves on Electron Diffraction

The effect of inelastic scattering on electron diffraction by crystals is theoretically studied. It is proved that the effect of inelastic scattering gives rise to an additional complex term to Fourier coefficient of the inner potential. The imaginary part of the additional term explains qualitatively the observation that two components of a doubly refracted electron beam are subjected to different degrees of absorption (Honjo and Mihama, J. Phys. Soc. Japan 9 (1954) 184). The real part of the additional term gives a correction of about 6∼7 % to the calculated value of mean inner potential at accelerating voltages of 30∼40 kv. This explains the systematic difference between the mean inner potential experimentally obtained by electron diffraction and that calculated by the use of diamagnetic susceptibility (Miyake, Proc. Physico-Math. Soc. Japan 22 (1940) 666).