Fullerenes adsorption on Cu(111) and Ag(111) surfaces

Initial stage adsorption and film growth of C₆₀, C₇₀, C_60(x)C_70(1-x), and Sc₂@C₈₄ fullerene molecules on Cu(111) and Ag(111) surfaces have been investigated by field-ion scanning tunneling microscopy. Fullerene molecules are mobile on the terrace and initially segregate to the step edges. A well-ordered monolayer films form with a close-packed arrangement upon annealing the fullerence-covered surfaces. The (4×4) phases form in the case of the C₆₀, C₇₀, and C_60(x) C_70(1-x) adsorption on the Cu(111)-(1×1) surface, indicating a strong interaction between the Cu substrate and fullerenes. Intramolecular structures of the C₆₀ and C₇₀ molecules are observed and interpreted as the mappings of the local electron density of states. On the Ag(111) surface, C₆₀ and Sc₂@C₈₄ monolayer films show several phases that have almost identical nearest neighbor distance but are rotated from each other, indicating weaker interaction between the Ag substrate and fullerenes compared with the case of Cu.