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

Mittendorff, Martin; Winzer, Torben; Malic, Ermin; Knorr, Andreas; Berger, Claire; de Heer, Walter A; Schneider, Harald; Helm, Manfred et al. · Nano Lett · 2014

basic_science · Level V

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Abstract

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 giving rise to an isotropic carrier distribution.