2014 Fast electron energy loss spectroscopy (FEELS) is used to obtain the various optical constants over a large energy range in Sc, Sc2O3, Y, Y2O3, Gd, Gd2O3, Dy, LaF3, GdF3, DyF3, Th, ThF4, U and UF4. For the first time a comprehensive study of the 3p to 6p spectra is performed in the 30-60 eV range, Z varying between 21 and 92. Interesting common features of these resonant p spectra are emph...