Figure 2: SERS of monolayer WS2 at room temperature.
From: Surface enhanced Raman scattering of monolayer MX2 with metallic nano particles

(a) Schematic drawing of the experimental setup for the SERS measurements of WS2. (b) Raman spectra of monolayer WS2 with (Red) and without (Black) 5 nm nominally thick Ag NPs on top. Arrow indicates the splitting of the
mode. (c) SEM image of 5 nm nominally thick Ag NPs on monolayer WS2. (d) Simulated electric field cartography at the surface of the area marked in Fig. 2c with an excitation wavelength of 532 nm.