Interlayer Raman modes in twisted bilayer transition metal dichalcogenides

Interlayer coupling is crucial for the observation of twist-angle induced physical effects in twisted 2D layers. This paper presents a fast method to investigate the interlayer coupling in twisted bilayer transition metal dichalcogenides by Raman spectroscopy. Via resonant excitation near the $C$ exciton energy of the material, so-called interlayer optical Raman modes become observable only if the layers are electronically coupled. The authors demonstrate this effect specifically for twisted bilayers of MoS${}_{2}$ and MoSe${}_{2}$ at multiple twist angles.