Optical chirality in Raman scattering

Raman optical activity (ROA) offers a powerful tool for distinguishing chiral molecules. However, the inherent properties of light that unveil the “handedness” of molecules remain unclear in the realm of ROA. Here, we find two optical measures—the optical chirality tensor and the optical quadrupole tensor—that contribute to ROA excitations. Subsequently, we propose a theoretical framework to elucidate the relationship between the optical chirality quantities and their molecular counterparts in Raman scattering. This framework allows for more selective and tunable ROA excitations. As a demonstration, we identify linearly polarized standing waves as a good configuration for superchiral ROA excitations, where the optical chirality is locally enhanced. Our work provides insights into optical chirality and paves the way to precisely manipulate chiroptical responses.