Interaction of charged particles with a graphene monolayer modeled as a set of electronic oscillators

摘要

We assess the applicability of the oscillator model to evaluate the energy loss of a fast charged particle incident on graphene. We study the cases of a parallel and perpendicular trajectory of the particle. We focus on two frequency regimes for graphene's electron response: the optical regime, which is dominated by two types of oscillators with non-dispersing frequencies in the ultraviolet regime, and the terahertz (THz) regime, which is dominated by a strongly dispersing sheet plasmon mode in doped graphene. In the latter regime, we invoke the kinematic resonance condition for a parallel trajectory, and we propose a method for averaging the energy loss for a perpendicular trajectory. We show that the oscillator model provides analytical expressions, which give results in generally good agreement with a dielectric-response approach to the same problem, even in the THz regime.