Band gap of atomically precise graphene nanoribbons as a function of ribbon length and termination.

  title={Band gap of atomically precise graphene nanoribbons as a function of ribbon length and termination.},
  author={Leopold Talirz and Hajo S{\"o}de and Shigeki Kawai and Pascal Ruffieux and Ernst Meyer and Xinliang Feng and Klaus M{\"u}llen and Roman Fasel and Carlo A. Pignedoli and Daniele Passerone},
  journal={Chemphyschem : a European journal of chemical physics and physical chemistry},
We study the band gap of finite $N_A=7$ armchair graphene nanoribbons (7-AGNRs) on Au(111) through scanning tunneling microscopy/spectroscopy combined with density functional theory calculations. The band gap of 7-AGNRs with lengths of 6 nm and more is converged to within 0.1 eV of its bulk value of 2.3 eV, while the band gap opens by several hundred meV in very short 7-AGNRs. The termination has a significant effect on the band gap, doubly hydrogenated termini yielding a lower band gap than… 
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