Über die Winkelabhängigkeit und ihre Unsymmetrie von Energieverlusten an Si und Ge
In Silicon and Germanium one finds three types of characteristic energy losses: the plasma loss at 17 eV in transmission of electrons through thin films, the 10 eV loss in reflection at cleavage surfaces, and the 5 eV loss in transmission through extremely thin films. The present paper is concerned with the 5 eV loss.It is found that the intensity of the 5 eV loss does not depend on variation of thickness of the foils. Thus, it is concluded that the 5 eV loss is due to surface plasma oscillations. In fact, measuring the angular distribution, there is found a dependence of ∼ϑ−3 in good agreement with that given by the theory.In the case of non-normally incident electrons it is found that the intensity of this loss is not symmetric about the direction of the incident electrons. This is in agreement with the theoretical considerations ofStern andFerrell, and represents a further typical feature of surface plasma losses.