Electron-energy-loss spectra of vanadium, niobium, molybdenum, and tantalum

Electron-energy-loss spectra were obtained out to approximately 80 eV in the reflection mode from atomically clean foil samples of vanadium, niobium, molybdenum, and tantalum. Results are compared with previous ultraviolet optical work and electron-energy-loss spectroscopy (ELS) studies on these materials. Resolution of structure is improved over many previous ELS investigations by using synchronous detection techniques in determining energy locations. Origins of the various observed structures are discussed in light of previous studies, particularly ultraviolet optical work leading to the determination of the complex dielectric function. We comment on discrepancies existing in the literature about plasmon energies in these materials estimated from infrared optical measurements.