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

Kleimeier NF, Timmer A, Bignardi L, Mönig H, Feng XL, Müllen K, Chi LF, Fuchs H, Zacharias H

Abstract

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 hν=3.15 eV was carried out to measure the lifetimes of states located at E1-EF=3.6 eV and E2-EF=3.8 eV via a resonant excitation from an unoccupied state at E-EF=0.6eV. Lifetimes of τ1=(110±13)fs and τ2=(75±10)fs are observed, respectively.