Elastic scattering effects in the electron mean free path in a graphite overlayer studied by PES and LEED

We measure variations due to a an epitaxial graphite overlayer on SiC in the Si 2p core level signal using synchrotron radiation photoelectron spectroscopy at low kinetic energy. The intensity minima in the Si 2p signal correspond to the final-state band gaps predicted from Very Low Energy Electron Diffraction (VLEED), whereby the experimental values of the energy dependent Vi are derived from the widths of the I(V) spectral structures, and calculations of the complex band structure of the final states are performed with the Bloch wave damping constants giving the mean free path. In graphite there are significant diffraction minima in the final-state band gaps.