Direct probe of linearly dispersing 2D interband plasmons in a free-standing graphene monolayer

In low-dimensional systems, a detailed understanding of plasmons and their dispersion relation is crucial for applying their optical response in the field of plasmonics. Electron energy-loss spectroscopy is a direct probe of these excitations. Here we report on electron energy-loss spectroscopy results on the dispersion of the pi plasmons in free-standing graphene monolayers at the momentum range of 0