Interband, collective and atomic (p, d) excitations from 2 to 160 eV in Sc, Y, lanthanides and actinides and in some of their compounds by FEELS

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 emphasized and discussed in the light of recent theoretical work. Below 30 eV, strong interband transitions are observed in the wide gap insulators (oxides and fluorides), while the metal spectra are dominated by collective or plasmon excitations. At higher energies, 4d-lanthanide and 5d-actinide spectra are compared with X-UV photoabsorption measurements. J. Physique 41 (1980) 603-613 JUILLET 1980,