Gas phase electronic spectrum of the nitrogen terminated nanowire NC16N

The UV electronic spectrum of NC16N has been measured by means of a mass selective resonant two-color two-photon ionization technique. The observed bands are assigned to the dipole allowed, B1Σu+←X1Σg+, electronic transition. The electronic structures of NC2nN (n=2–8) in the ground and excited states have been investigated using density functional theory. The calculated transition energies of the A1Δu(1Σu−)←X1Σg+ and the B1Σu+←X1Σg+ systems decrease monotonically with increasing chain size and slowly converge to the HOMO–LUMO gap of the long chain limit. The present studies imply that a long carbon nanowire terminated with nitrogen will be semiconducting due to π-electron localization and bond-length alternation.