ELECTRONIC-TRANSITIONS AND EXCITATIONS IN SOLID C-70 STUDIED BY REFLECTION ELECTRON-ENERGY-LOSS SPECTROSCOPY

The electronic transition and excitation properties of highly ordered C70 films have been studied by reflection electron energy loss spectroscopy (EELS). The EELS study revealed a total of eleven features in the energy loss range 1–40 eV. These include a prominent peak at 2.55 eV revealing the first dipole allowed transition across the band gap in C70 fullerite; a feature at 2.20 eV correlated with the electron transition between the highest-occupied-molecular-orbital- and lowest-unoccupied-molecular-orbital-derived bands; two excitonic levels corresponding to a tight-binding Frenkel exciton in C70 fullerite at 1.53 and 1.88 eV; and a doublet at 5.2 and 5.9 eV showing evidence of the π-plasmon splitting in fullerite C70. A broad hump at —28 eV corresponds to the excitation of the (σ+ π) plasmon. © 1995, American Vacuum Society. All rights reserved.