Optical Investigation of On-Surface Synthesized Armchair Graphene Nanoribbons

International audienceOn-surface synthesized N ¼ 9-armchair graphene nanoribbons (AGNRs) are investigated by Raman spectroscopy and AFM/micro photoluminescence measurements. In order to perform the optical experiments, the AGNR film is transferred on a glass substrate through a non-membrane method. The Raman spectroscopy shows the radial breathing-like mode characteristic of the 1D nature of GNRs, proving the efficiency of the transfer method. Then, the results of combined AFM/micro photoluminescence measurements are discussed. First, the observation of high-order Raman lines suggests the 1D nature of the electron–phonon coupling in GNR, similar to the case of carbon nanotubes. Secondly, the origin of the broad luminescence line is discussed in comparison with the predicted gap energy of the 9-AGNR. Due to its width and energy range, the emission is interpreted as arising from defect sites, missing phenyl rings for instance, that occur during the synthesis of these specific armchair nanoribbons