Highly Ordered C60 Monolayer Self-Assembled by Using an Iodine Template on an Au(111) Surface in Solution

An iodine-modified Au(111) surface, (I/Au(111)), was used as a substrate to prepare a C-60 adlayer by self-organization in a benzene solution. A highly ordered C-60 adlayer was successfully prepared due to the moderate C-60-I/Au(111) interaction. Two lattice structures, (2 root 3 x 2 root 3)R30 degrees and p(2 x 2), were imaged for this C-60 adlayer. For the first structure, a featureless ball-like molecular shape was imaged, ascribed to the molecular rotation resulting from a symmetrical location between C-60 and iodine atoms. For the p(2 x 2) structure, the asymmetrical location of C-60 with respect to the iodine atoms freezes the C-60 molecules on the substrate, leading to a clear image of intramolecular structure. The intermediate iodine atoms in the C-60/I/Au(111) adlayer can be desorbed by electrochemically reduction without significantly affecting the ordering of the C-60 adlayer. However, the internal pattern of C-60 disappears in the absence of iodine.