Adlayers of fullerene monomer and [2+2]-type dimer on au(111) in aqueous solution studied by in situ scanning tunneling microscopy

In situ scanning tunneling microscopy (STM) revealed that highly ordered adlayers of fullerene monomer (C-60) and [2 + 2]-type dimer (C-120) were formed on Au(111) by immersing the surface in benzene solution containing C-60 or C120 molecules. High-resolution STM images allowed us to determine packing arrangements of C60 and C-120 on a Au(111) surface in an aqueous HClO4 solution. The (2 root3 x 2 root3)R30degrees and the so-called in-phase structures of the C-60 adlayer were found on the Au(111) surface, whereas the (2 root3 x 4 root3)R30degrees and (2 root3 x 5 root3)R30degrees structures were observed for the C-120 dimer. Each C-120 dimer was imaged in a dumbbell shape by in situ STM.