Vacuum ultraviolet reflectivity spectra of the molybdenum and tungsten dichalcogenides

Abstract

Normal-incidence vacuum ultraviolet reflectivity spectra in the range 41/2 to 14 eV have been measured from the basal faces of single crystals of the dichalcogenides of W and Mo (with the exception of WTe2). Correlations between the spectra are interpreted in terms of chemical effects in the band structures and models for the conduction bands of the Mo and W compounds are proposed, which account for the absence of strong plasma effects in the W compounds.