By using an electron-energy analyzer adapted on a high-voltage electron microscope, energy-loss straggling of relativistic electrons (0.3-1.2 MeV) through 1- to 8.5-μm-thick aluminum foils has been investigated in the energy range 0-4000 eV. The energy resolution of the analysis is 3 eV. The experimental values of the most probable energy loss $\Delta E_p$ and of the full width at half maximum $\Delta E_{\frac{1}{2}}$ are interpreted by taking account of the effects of all-order terms in the Landau theory. This latter is revisited by introducing the relativistic Bethe cross section associated with all kinds of excitation processes including plasmons; it is observed that plasmon influence is negligible in this thickness and energy range.

• Received 10 December 1976

DOI:https://doi.org/10.1103/PhysRevA.16.1061