Regensburg 2022 – scientific programme
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O: Fachverband Oberflächenphysik
O 7: New Methods and Developments 1: Scanning Probe Techniques 1 (joint session O/KFM)
O 7.5: Talk
Monday, September 5, 2022, 11:45–12:00, S053
Femtosecond Tip-Enhanced Coherent Anti-Stokes Raman Spectroscopy of a Single Graphene Nanoribbon — •Yang Luo1, Alberto Martin-Jimenez1, Manish Garg1, and Klaus Kern1,2 — 1Max Planck Institute for Solid State Research, Stuttgart, Germany — 2Institut de Physique, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
By integration of ultrashort laser pulses with a scanning tunneling microscope (STM) one can study the electronic and carrier dynamics with very high spatial and temporal resolution. Nevertheless, molecular vibrational modes at the single-molecule level are difficult to track, owing to the lack of energy resolution. To overcome this barrier, we have now integrated a local spectroscopic tool, combining ultrafast laser pulses with an STM-based tip-enhanced Raman spectroscopy (TERS). By performing TERS with femtosecond laser pulses, we have tracked vibrational coherences and phonon dephasing dynamics in a single graphene nanoribbon (7-GNR). The decoherence time (T2/2 ~ 440 fs) of the phonons in a GNR has been obtained from the time-resolved coherent anti-Stokes Raman spectra. Temporal evolution of vibrational coherences (beatings) between different phonon modes in the GNR has been measured, which evolve on time scales as short as ~ 100 fs. This work lays the foundation for investigating intramolecular vibrational coherences and vibronic dynamics with utmost spatial, temporal and energy resolutions, simultaneously.