Using a surface segregation technique, single-layer graphene can be grown on a carbon-doped Pd(1 1 1) substrate. The growth was monitored and visualized using Auger electron spectroscopy, X-ray photoelectron spectroscopy, Raman microscopy, atomic force microscopy and scanning tunneling microscopy. Appropriate adjustment of annealing parameters enables controllable growth of single-layer graphene islands and homogeneous, wafer-scale, single-layer graphene. The chemical state of the C 1s peak from X-ray photoelectron spectroscopy indicates there is almost no charge transfer between graphene and the Pd(1 1 1) substrate, suggesting weak graphene–substrate interaction. These findings show surface segregation to be an effective method for synthesizing large-scale graphene for fundamental research as well as potential applications.

An ultrahigh-vacuum scanning tunneling microscope with an optically transparent tip was used to excite photon emission from a clean Cu(1 0 0) surface and a sub-monolayer of Cu-tetra-[3,5-di-t-butylphenyl]porphyrin (Cu-TBPP) molecules chemisorbed on a Cu(1 0 0) surface. Photons generated in a nanometer-scale area just under the tip were collected within the near-field region through the apex of the optical fiber tip. Two kinds of mechanisms for the photon emission from a Cu-TBPP/Cu(1 0 0) surface are proposed. The quantum efficiency for molecular fluorescence induced by inelastic tunneling was estimated to be ∼3×10−6 photons/electron.