Molecular orientations and interfacial structure of C60 on Pt(111)

Abstract

Molecular orientations and assembled structures of C(60) molecules on Pt(111) have been characterized by low-temperature scanning tunneling microscopy for coverage between 0.1 ML and 1.5 ML. At room temperature, C(60) molecules preferentially decorate the steps and nucleate into single layer islands (SLIs) with hexagonal close-packed structures upon increasing coverage. C(60) islands comprise two differently oriented C(60)∕Pt(111)-(√13 × √13) R13.9° phases, in which five types of molecular orientation of C(60) carbon cage configurations are clearly identified by the high-resolution scanning tunneling microscopy image. Further annealing treatment leads to more uniform molecular orientation without apparent aggregation of C(60) SLIs. As coverage increases above 1 ML, domains corresponding to (2√3 × 2√3) R30° superstructure appear. To explain the above transformation, an interfacial reconstruction model is proposed according to the detailed study of the molecular adsorption structures in different domains.