Bi-layer graphene with a twist angle \theta\ between the layers generates a superlattice structure known as Moir\'{e} pattern. This superlattice provides a \theta-dependent q wavevector that activates phonons in the interior of the Brillouin zone. Here we show that this superlattice-induced Raman scattering can be used to probe the phonon dispersion in twisted bi-layer graphene (tBLG). The effect reported here is different from the broadly studied double-resonance in graphene-related materials in many aspects, and despite the absence of stacking order in tBLG, layer breathing vibrations (namely ZO' phonons) are observed.
@article{arxiv.1301.3795,
title = {Raman-scattering study of the phonon dispersion in twisted bi-layer graphene},
author = {J. Campos-Delgado and L. G. Cançado and C. A. Achete and A. Jorio and J. -P. Raskin},
journal= {arXiv preprint arXiv:1301.3795},
year = {2013}
}