Figure 1. The linear absorption spectra of WS₂ atomically thin films.

(a) Normalized differential transmission spectra of multi- and monolayer WS₂ at room temperature and 10 K. (b) Absorbance of atomically thin layer at photon energy of 2.088 eV (orange) and 2.331 eV (green) as indicated by arrows in figure 1(a). The absorbance shows a linearly dependence on layer number, each unit layer with constants of 2.0% and 3.4% respectively. (c) Absorption peak energy values of exciton “A”, “B” and “C”.