The C60/Au(111) interface at room temperature: A scanning tunnelling microscopy study

The interface between adsorbed C-60 Molecules and the (111) surface of gold at room temperature has been studied with the scanning tunnelling microscopy (STM). The first monolayer of C-60 on Au(111) is known to exist in several phases: in phase, 2 root 3 x 2 root 3R30 degrees, and R14 degrees, depending on the direction of the close-packed C-60 molecules in relation to the close-packing direction of the gold atoms. For the in-phase C-60 overlayer where the close-packing direction of the C-60 molecules is aligned with that of the gold atoms, we find that the 22 x root 3 reconstruction of the underlying Au(111) surface remains largely unchanged. For the 2 root 3 x 2 root 3R30 degrees phase, the surface reconstruction is also preserved to a great extent if the molecular layer sits on a region consisting of small 22 x root 3 domains. On a larger domain, the 2 root 3 x 2 root 3R30 degrees structure is found to lift the surface reconstruction of Au(111). The R14 degrees structure is observed for the first time in STM and a structural model consistent with findings from both STM and LEED is presented. A fairly regular pattern of atomic re-arrangement with a quasi-period of similar to 6 nm is found in regions of the Au(111) surface underneath the R14 degrees C-60 layer. (C) 2008 Elsevier B.V. All rights reserved.