Modification of the valence band electronic structure under Ag intercalation underneath graphite monolayer on Ni(111)

摘要

Angle-resolved photoemission spectroscopy and Auger electron spectroscopyhave been applied to study the intercalation process of silver underneath amonolayer of graphite (MG) on Ni(111). The room-temperature deposition ofsilver on top of MG/Ni(111) system leads to the islands-like growth of Ag ontop of the MG. Annealing of the "as-deposited" system at temperature of 350-450C results in the intercalation of about 1-2 ML of Ag underneath MG on Ni(111)independently of the thickness of pre-deposited Ag film (3-100 A). Theintercalation of Ag is followed by a shift of the graphite-derived valence bandstates towards energies which are slightly larger than ones characteristic forpristine graphite. This observation is understood in terms of a weakening ofchemical bonding between the MG and the substrate in the MG/Ag/Ni(111) systemwith a small MG/Ni(111) covalent contribution to this interaction.