Reflection Valence- and Inner-Shell-Electrons Energy-Loss Spectra of SnS2and Momentum-Transfer Effects

The valence-electron and inner-shell-electron energy-loss spectra of SnS 2 are measured in reflection geometry. They are compared with the transmission electron-energy-loss spectroscopy (TEELS) spectra at various momentum transfers, the S K X-ray-absorption spectroscopy (XAS) spectrum, the reflectivity (R) spectrum, and the bremsstrahlung-isochromat spectroscopy (BIS) spectrum. The plasmon energy estimated at E 0 =1000 eV is 18.8 eV, which is equal to the one at the momentum transfer of 0.34 Å -1 . The valence-electron REELS spectrum satisfies the dipole selection rules only to the first approximation. It seems that indirect and optically-forbidden transitions affect the energy-loss structures related to interband transitions. The inner-shell-electron REELS spectra are compatible to the XAS, the core R, and the BIS spectra except for the fact that optically-forbidden transitions are clearly observed in REELS when using low incident-energy beams.