Evolution of the EELS fine structure on the Al L₂₃ edge when drilling a hole in a grain of non-carbon coated α-Al₂O₃ thin foil : (a) raw chrono-spectral sequence demonstrating the evolution of the edge during the reduction of alumina into aluminum; b) selection of spectra from the previous time-dependent sequence pointing out changes at the edge and above the edge (from Bouchet and Colliex [157]).