Self-assembly and ordering of C₆₀ on the WO₂/W(110) surface

The growth and ordering of C-60 molecules on the WO2/W(110) surface have been studied by low-temperature scanning tunnelling microscopy and spectroscopy (STM and STS), low-energy electron diffraction (LEED), and density functional theory (DFT) calculations. The results indicate the growth of a well-ordered C-60 layer on the WO2/W(110) surface in which the molecules form a close-packed hexagonal structure with a unit cell parameter equal to 0.95 nm. The nucleation of the C-60 layer starts at the substrate's inner step edges. Low-temperature STM of C-60 molecules performed at 78 K demonstrates well-resolved molecular orbitals within individual molecules. In the C-60 monolayer on the WO2/W(110) surface, the molecules are aligned in one direction due to intermolecular interaction, as shown by the ordered molecular orbitals of individual C-60. STS data obtained from the C-60 monolayer on the WO2/W(110) surface are in good agreement with DFT calculations.