Mean Free Path of Fast Electrons for Plasmon Excitation in a Single Crystal

Abstract

The mean free path of 40–100 KeV electrons for plasmon excitation was measured by analysing energy spectra of bright field images of aluminum single crystal. Equal thickness fringes by (111) reflection were used to measure the specimen thickness. It was found that the mean free path slightly depends on the crystal orientation, and its voltage dependence at the exact Bragg condition agrees qualitatively well with Ferrell's theory (Phys. Rev. 101 (1956). 554).