Kramers-Kronig analysis of the reflectivity spectra of 3R-WS2and 2H-WSe2

Using extrapolations to 0 eV and 30 eV of experimental data in the energy range 1.5 eV to 14 eV, a Kramers-Kronig analysis of the reflectivity spectra at both room temperature and liquid nitrogen temperature from the basal plane (E perpendicular to c) of single crystals of 3R-WE2 and 2H-WSe2 has been performed. The optical data so obtained has been discussed and interpreted in terms of the proposed band model for these materials.