Electron Self-energy Effect Measured By Hreels of Surface-plasmons

We calculate the surface plasmons contribution to the inelastic scattering cross-section of low-energy electrons reflected from a metal surface. We show that one must go beyond the simple Born approximation in order to explain recent experimental results exhibiting a minimum in the loss peak at a nonzero momentum transfer. The many-body processes responsible for the shift may be incorporated into an optical potential