Femtosecond carrier dynamics in bulk graphite and graphene paper

Femtosecond white-light continuum probe transient absorption and reflectivity measurements of bulk graphite and graphene paper are reported. In graphite, the relaxation of photoinduced electron–hole pairs happens through in-plane electron–electron and electron–phonon scattering in â200 fs, while the ps dynamics is due to the modulation of the electronic structure by out-of-plane structural motions. The ps dynamics of the optical signal is strongly reduced in graphene paper, where the out-of-plane bond is disrupted, while the short component of the dynamics is identical in both materials. These results show that in 2D-graphene, the carrier relaxation occurs in â200 fs. ⺠Fs pump-probe transmission and reflectivity of graphite and graphene paper are reported. ⺠Two decays of the excitation are observed in both materials, one ultrafast, 200 fs, and a the other slower, 2 ps. ⺠The ultrafast decay is identical in both systems, the slow one is suppressed in grapheme paper. ⺠The ultrafast decay is due to electron-electron and electron-phonon scattering within the graphene sheets. ⺠The slow decay is due to interlayer electron-phonon scattering and anharmonic couplings.