Atomic Structure of Monolayer Graphite Formed on Ni(111).

Abstract

The atomic structure of monolayer graphite formed on a Ni (111) surface was investigated by means of LEED intensity analysis. We measured the I-V curves of the (1, 0), (0, 1) and (1, 1) diffraction spots from a 1×1 atomic structure, and analyzed them by using the Van Hove's analytical program based on dynamical theory. Three different atomic structures meeting the experimental requirement of the 3-m symmetry were evaluated with Pendry's reliability factor. The final best-fit structure characterized by the minimum Pendry's reliability factor of 0.22 is as follows; one carbon atom in a unit cell of the graphite overlayer is located at the on-top site of the topmost Ni atoms, while another carbon atom exists at the fcc-hollow site. The spacing between the flat overlayer and the topmost Ni layer is 2.11 ± 0.07 A, which is much narrower than the interlayer spacing in bulk graphite (3.35 A).