Observing the Angular Distribution of Raman Scattered Fields.

In conventional optical spectroscopy, lenses are used to focus light on the sample and to collect light scattered from the sample. Focusing increases the signal intensity, but it amounts to angular (k-space) averaging and leads to information loss. In this issue of ACS Nano, Budde and collaborators record radiation patterns of Raman scattering from a single layer of graphene, revealing the angular distribution of the scattered field. The authors show that the radiation patterns render the spatial symmetry of vibrational modes. Furthermore, their results demonstrate that depolarization effects occurring in the focal region must be taken into account for proper interpretation of Raman intensities. We outline here the working principle of this new approach and discuss future applications for studies of graphene and other low-dimensional systems.