Plasmons in Graphene Nanostructures with Point Defects and Impurities

The exceptional electronic and optical properties of graphene are harmed by the unavoidable imperfections of the lattice resulting from mechanical or electronic interaction with the environment. Using a time-dependent approach, we theoretically address the sensitivity of the plasmon modes of graphene nanoflakes to the presence of point vacancy defects and substitutional impurities. We find that the fractions of the defects as low as 10^–3 from the total number of carbon atoms in an ideal nanoflake lead to strong broadening of the plasmon resonance in the optical absorption spectrum. In addition to this effect resulting from the elastic and inelastic processes associated with defect-induced scattering and modification of the electronic structure of graphene, we also observe and explain the vacancy and impurity-induced shifts of the plasmon energy. Our work extends the in depth theoretical studies of the optical properties of graphene nanomaterials toward practical situations of nonideal 2D lattices.