Anisotropy of excitation and relaxation of photogenerated charge carriers in graphene.

  title={Anisotropy of excitation and relaxation of photogenerated charge carriers in graphene.},
  author={Martin Mittendorff and Torben Winzer and Ermin Malic and Andreas Knorr and Claire Berger and Walt A. de Heer and Harald Schneider and Manfred Helm and Stephan Winnerl},
  journal={Nano letters},
  volume={14 3},
We present a pump-probe experiment on graphene, which reveals a pronounced dependence of the pump-induced transmission on the angle between pump and probe polarization. It reflects a strong anisotropy of the pump-induced occupation of photogenerated carriers in momentum space. Within 150 fs after excitation, an isotropic carrier distribution is established. The experiments are well described by microscopic modeling, which identifies carrier-phonon scattering to be the main relaxation mechanism… 

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