By use of a “ Gegenfeld ” filter the ratios of intensities of electron diffraction rings from evaporated aluminium films (100∼550 A in thicknesses) have been measured from various energy losses of the incident electrons. For elastic scattering and for 7 eV loss (surface plasmon loss) the intensity ratios show some effects of dynamical scattering. For 15 eV loss (volume plasmon loss) they are more nearly kinematical. For a narrow loss region at 3 eV and again at 10 eV the ratios show strong anomalies. These results are explained through intensity calculations band on n -beam dynamical diffraction theory. In particular, the anomalous intensity ratios are attributed to the effects of single-electron excitations in the crystals.