Intercalation of copper underneath a monolayer of graphite on Ni(111)

Angle-resolved photoemission and scanning tunneling microscopy have been applied to study the intercalation of copper underneath a monolayer of graphite (MG) on Ni(111). The room-temperature deposition of copper on MG/Ni(111)in the coverage range 4-12 Angstrom leads to the growth of Cu islands on the MG. Annealing of the "as-deposited'' system at a temperature of 400 degreesC results in the intercalation of all Cu atoms underneath the MG. The intercalation of Cu is followed by a shift of the graphite-derived valence bands toward energies that are characteristic of pristine graphite. This observation is understood in terms of a weakening of chemical bonding between the MG and the substrate in the MG/Cu/Ni(111) system.