The deuterium edge-termination effects on the electronic states of nanographene on Pt(111) have been investigated by three-photon photoemission and ultraviolet photoelectron spectroscopy. The antibonding ${\sigma }^{*}$ state at $\overline{\Gamma }$ of nanographene with the average diameter of $\sim 60\hspace{0.5em}\mathrm{\AA }$ is found at $3.87\pm 0.05\hspace{0.5em}\mathrm{eV}$ above the Fermi level. Although both the ${\sigma }^{*}$ state and the occupied $\pi$ state at 8.1 eV show bulklike behavior, they are strongly affected by deuterium bonding to carbon atoms at the edges of nanographene. In particular, the ${\sigma }^{*}$ state is highly sensitive to the edge termination compared to the $\pi$ state.

• Received 5 April 2002

DOI:https://doi.org/10.1103/PhysRevB.65.241402