Core-hole effects on electron energy-loss spectroscopy of Li₂O

Excitons in electron-energy-loss spectra (EELS) can be overwhelming in some materials. Here we report EELS from Li₂O for both Li and O K edges. Comparison with calculations excluding and including core-hole effects suggests that the one-electron (ground state) band structure theory is not valid for the interpretation of the fine structure in EELS of Li₂O. Using a large angle scattering technique, a core exciton in the band gap can be observed in the K edge EELS.