Berlin 2015 – scientific programme
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O: Fachverband Oberflächenphysik
O 16: Graphene: Theory (HL with O/TT)
O 16.3: Talk
Monday, March 16, 2015, 15:30–15:45, ER 164
Edge effects in the Raman spectra of atomically precise graphene nanoribbons: an ab-initio study — Marzio De Corato1,2, Deborah Prezzi2, Alice Ruini1,2, and •Elisa Molinari1,2 — 1Department of Physics, Mathematics, and Informatics, University of Modena and Reggio Emilia, 41125 Modena, Italy — 2CNR-Nanoscience Institute, S3 Center, 41125 Modena, Italy
Bottom-up techniques have proven successful to achieve ultra-narrow and structurally well-defined graphene nanoribbons (GNRs) [1-2], where different edge shapes and terminations can be obtained by varying the molecular precursors. In this work we perform density-functional perturbation theory calculations to investigate the vibrational properties of GNRs with cove-type edge structure and variable width, similar to those produced in Ref. 2. By comparison with other prototype systems, we show that the phonon modes and the Raman spectra of these systems strongly depend on the specific edge morphology. This is particularly evident in the acoustic region, where the Radial-Like Breathing Mode (RLBM) shows sensible changes when the edge termination is modified. This makes the Raman spectrum of these GNRs very different from the case of both carbon nanotubes and ribbons with ideal armchair or zigzag edges, where the breathing mode depends on the lateral size only. Our results are in very good agreement with recent experimental data [2].
[1] J. Cai et al., Nature (London) 466, 470 (2010). [2] A. Narita et al., Nature Chem. 6, 126 (2014).