Dynamics of bulk versus nanoscale W S 2 : Local strain and charging effects

We measured the infrared vibrational properties of bulk and nanoparticle $\mathrm{W}{\mathrm{S}}_{2}$ in order to investigate the structure-property relations in these materials. In addition to the symmetry-breaking effects of local strain, nanoparticle curvature modifies the local charging environment of the bulk material. Performing a charge analysis on the $xy$-polarized ${E}_{1u}$ vibrational mode, we find an approximate 1.5:1 intralayer charge difference between the layered 2H material and inorganic fullerene-like (IF) nanoparticles. This effective charge difference may impact the solid-state lubrication properties of nanoscale metal dichalcogenides.