Molecular orientation and electronic structure of epitaxial bucky ferrocene (Fe(C₆₀(CH₃)₅)C₅H ₅) thin films

Single crystalline epitaxial films of bucky ferrocene (Fe(C ₆₀(CH₃)₅)C₅H₅), a hybrid molecule of C₆₀ and ferrocene, were grown on MoS₂(0001) substrates. By using reflection high-energy electron diffraction (RHEED) amplified by a microchannel plate (MCP), it was found that the lattice constant of the film decreased from 11.3 ± 0.2 Å at 1-2 monolayer (ML) to 10.2 ± 0.2 Å at 3 ML or thicker. Both of the lattice constants were incommensurate with that of the substrate, which indicates a new type of epitaxial growth. Valence electronic structures of the films at each thickness were measured with ultraviolet photoelectron spectroscopy (UPS) and the energy levels of molecular orbitals were identified in relation to the molecular orientation in the epitaxial film.