Resonance effects in the Raman scattering of monolayer and few-layer MoSe 2

Using resonant Raman scattering spectroscopy with 25 different laser lines, we describe the Raman scattering spectra of monolayer and multilayer 2H-molybdenum diselenide $({\mathrm{MoSe}}_{2})$ as well as the different resonances affecting the most pronounced features. For high-energy phonons, both $A$- and $E$-symmetry type phonons present resonances with $A$ and $B$ excitons of ${\mathrm{MoSe}}_{2}$ together with a marked increase of intensity when exciting at higher energy, close to the $C$-exciton energy. We observe symmetry-dependent exciton-phonon coupling affecting mainly the low-energy rigid layer phonon modes. The shear mode for multilayer displays a pronounced resonance with the $C$ exciton while the breathing mode has an intensity that grows with the excitation laser energy, indicating a resonance with electronic excitations at energies higher than that of the $C$ exciton.