Electronic Energy States of Tungsten Dichalcogenides by Low Energy Electron Loss Spectroscopy Study

Low energy electron loss spectroscopy (ELS) was performed on tungsten dichalcogenides (WS 2 and WSe 2 ) by using incident electron energies of 30–360 eV. The ELS spectra in the second derivative form had considerable structures. Maxima in density of states in the conduction band of the compound were determined from the ELS data due to excitations from different filled states, including core levels, which were studied by X-ray photoelectron spectroscopy. The conduction band of the tungsten disulfide could bc divided into two parts. The results are discussed in relation to previous proposals based on band calculations and experimental studies of group VIB dichalcogenides.