Speaker
Description
The conversion of energy, between photons, charge carriers, and the lattice is of fundamental importance to advance materials and devices, yet such insight remains incomplete due to experimental challenges in disentangling the various effects on overlapping time scales. Here, we show that attosecond core-level X-ray spectroscopy can identify these mechanisms with attosecond precision and across a picosecond range. We apply this methodology to graphite since its investigation is complicated by a variety of mechanisms occurring across a wide range of temporal scales. Our investigation reveals, through the simultaneous real-time measurement of electrons and holes, the different dephasing mechanisms for each carrier type dependent on excitation with few-cycle-duration light fields. We observe coherent excitation of the non-Raman active A1' phonon simultaneously with the Raman-active E2g phonon within only 20 fs by the incoherent electron-phonon scattering. Further, the measurement identifies the A1' phonon as the dominant channel for electronic de-excitation. These results demonstrate the general ability of our methodology to distinguish the various dynamic contributions to the flow of energy inside materials on their native time scales.
