Adsorption of 1,3,5-Triphenylbenzene Molecules and Growth of Graphene Nanoflakes on Cu(100) Surface^*

Abstract

Adsorption of 1,3,5-triphenylbenzene (TPB) molecules on Cu(100) surface is studied using ultraviolet photoelectron spectroscopy (UPS) and density functional theory (DFT) calculations. Researches on the bottom-up fabrication of graphene nanoflakes (GNFs) with TPB as a precursor on the Cu(100) surface are carried out based on UPS and DFT calculations. Three emission features d, e and f originating from the TPB molecules are located at 3.095, 7.326 and 9.349 eV below the Fermi level, respectively. With the increase of TPB coverage on the Cu(100) substrate, the work function decreases due to the formation of interfacial dipoles and charge (electron) rearrangement at the TPB/Cu(100) interface. Upon the formation of GNFs, five emission characteristic peaks of g, h, i, j and k originating from the GNFs are located at 1.100, 3.529, 6.984, 8.465 and 9.606 eV below the Fermi level, respectively. Angle resolved ultraviolet photoelectron spectroscopy (ARUPS) and DFT calculations indicate that TPB molecules adopt a lying-down configuration with their molecular plane nearly parallel to the Cu(100) substrate at the monolayer stage. At the same time, the lying-down configuration for the GNFs on the Cu(100) surface is also unveiled by ARUPS and DFT calculations.