Structure of epitaxial graphene on Ir(111)

A graphene monolayer has been prepared on an Ir(111) single crystal via pyrolytic cleavage of ethylene (C2H4). The resulting superstructure has been examined with scanning tunneling microscopy (STM) and low energy electron diffraction. It has been identified as a well aligned, incommensurate ( 9.32 x 9(32) pattern, which is described as a moire. This pattern shows three distinct regions resulting from different local configurations of the carbon adlayer with respect to the Ir-substrate. These regions are imaged differently by STM and differ strongly in their ability to bind metal deposits.