The interaction of electrons and phonons is of practical and fundamental interest in graphene, as it not only affects the transport properties of actual devices, but also induces novel phenomena such as charge density waves.

However, one of the big puzzles in the graphene community is why the experimentally measured electron-phonon interaction appears to be much stronger than the predicted one. Graphene on a metal (Cu) substrate allows us to modify its electronic properties as the electron-electron interactions are expected to be highly screened, thus removing velocity renormalization due to electronic correlations. As a result, we can extract the real electron-phonon interaction of graphene.