Terahertz spectroscopy of isolated graphene flakes inside polymer-based nanocomposite samples

We present transient THz spectroscopy studies of graphene nano-flakes imbedded in a polymer medium, forming a nanocomposite with 1% graphene content. We measured both the pure polymer and nanocomposite transmission spectra extending up to 4 THz and by comparing them obtained the absorption, the complex index of reflection, and conductivity of the embedded graphene. The conductivity results follow the Drude-Smith model with the imaginary part being negative, a property that indicates the total backscattering of carriers within the graphene grains.