Surface superstructures in highly oriented pyrolytic graphite surfaces after Ar+ bombardment

By combining a low dose of Ar+ ion bombardment on a highly oriented pyrolytic graphite surface and scanning tunnelling microscopy, we have been able to study different superstructures formed by the collision cascades of individual ion impacts. These superstructures may coexist; even interfere to give place to a new superstructure. Thus, we report the coexistence of a Moire pattern with a (root 3 x root 3)R30 degrees superstructure. Furthermore, the superposition of two (root 3 x root 3)R30 degrees superstructures forming a honeycomb one, leads us to suggest that the latter may be not a superstructure itself. (C) 2007 Elsevier B.V. All rights reserved.