Electron dynamics in unoccupied states of spatially aligned 7-a graphene nanoribbons on Au(788)

Bottom-up synthesized armchair graphene nanoribbons with a width of seven C=C bonds (7-aGNRs) have gained widespread interest due to their large band gap of about 2.8 eV and their atomically precise edge structures. Here, we report on the lifetime of excited states of spatially aligned 7-aGNRs grown on a vicinal Au(788) surface. Time-resolved three-photon photoemission spectroscopy at h nu = 3.15 eV was carried out to measure the lifetimes of states located at E-1-E-F = 3.6 eV and E-2-E-F = 3.8 eV via a resonant excitation from an unoccupied state at E-E-F = 0.6 eV. Lifetimes of tau(1) = (110 +/- 13) fs and tau(2) = (75 +/- 10) fs are observed, respectively.