Ab initio calculations of plasmons and interband transitions in the low-loss electron energy-loss spectrum

In the low-loss region of the electron energy-loss (EEL) spectrum interband transitions and plasmon losses are observed and can provide information about composition, electronic structure and optical properties. Low-loss EEL spectra have been calculated using density-functional theory (DFT) for a large number of elements and some simple compounds. Good agreement with experimental spectra is observed, allowing interpretation of the features in the spectrum. The calculations of the plasmon energies are improved over free-electron calculations for most materials. The improvements that have become available in the past few years, both in energy spectrometers and in the calculation methods, should see increasing numbers of applications of low-loss EELS to measure electronic structure and bonding.