Zenith-angle resolved polarized Raman spectroscopy of graphene

Angle resolved polarized Raman (ARPR) spectroscopy has been widely used to study basic properties of two-dimensional materials (2DMs), such as underlying symmetry, mode assignment, crystallographic orientation and optical anisotropy. The substrate effect has never been uncovered in ARPR spectroscopy. In this work, we investigated zenith-angle resolved polarized Raman (ZRPR) spectra of the G mode of graphene (1LG) deposited on different substrates as well as graphite under in-plane and out-of-plane configurations. In contrast to the independent behavior in normal incidence geometry, the G mode intensity exhibits obvious zenith-angle dependence. In particular, this polarization behavior is sensitive to the underlying substrates underneath 1LG. The ZRPR intensity of the G mode can be well understood by a model considering both Raman selection rule and zenith-angle resolved interference effect. This work enriches the understanding of polarized Raman spectroscopy of 2DMs and the approach can be applicable to other 2DMs, especially in-plane anisotropic 2DMs.