LAUSR

We studied helicity-resolved Raman scattering in PtSe2 flakes with different thicknesses. The peak amplitude of helicity-switched Raman scattering is significantly larger than that of helicity-conserved scattering for the in-plane E g mode, consistent with the Raman tensor analyses and conservation law of angular momentum. The peak amplitude of the helicity-switched E g mode is larger for the thinner flakes. In addition, we find Raman peaks near the energy levels of IR-active E u and A 2u modes, only for monolayer and a few-layers-thick flakes. Interestingly, these peaks manifest themselves only for helicity-switched Raman scattering; they are nearly absent for helicity-conserved scattering.