TY  - JOUR
A1  - Maass, Friedrich
A1  - Utecht, Manuel Martin
A1  - Stremlau, Stephan
A1  - Gille, Marie
A1  - Schwarz, Jutta
A1  - Hecht, Stefan
A1  - Klamroth, Tillmann
A1  - Tegeder, Petra
T1  - Electronic structure changes during the on-surface synthesis of nitrogen-doped chevron-shaped graphene nanoribbons
JF  - Physical review : B, Condensed matter and materials physics
N2  - Utilizing suitable precursor molecules, a thermally activated and surface-assisted synthesis results in the formation of defect-free graphene nanoribbons (GNRs), which exhibit electronic properties that are not present in extended graphene. Most importantly, they have a band gap in the order of a few electron volts, depending on the nanoribbon width. In this study, we investigate the electronic structure changes during the formation of GNRs, nitrogen-doped (singly and doubly N-doped) as well as non-N-doped chevron-shaped CGNRs on Au(111). Thus we determine the optical gaps of the precursor molecules, the intermediate nonaromatic polymers, and finally the aromatic GNRs, using high-resolution electron energy loss spectroscopy and density functional theory calculations. As expected, we find no influence of N-doping on the size of the optical gaps. The gap of the precursor molecules is around 4.5 eV. Polymerization leads to a reduction of the gap to a value of 3.2 eV due to elongation and thus enhanced delocalization. The CGNRs exhibit a band gap of 2.8 eV, thus the gap is further reduced in the nanoribbons, since they exhibit an extended delocalized pi-electron system.
Y1  - 2017
U6  - https://doi.org/10.1103/PhysRevB.96.045434
SN  - 2469-9950
SN  - 2469-9969
VL  - 96
PB  - American Physical Society
CY  - College Park
ER  -