Adsorption of Hydrocarbons on Complex Metallic Alloy Surfaces - Lubricants and Superlubricity Renee D. Diehl, Physics, Pennsylvania State University, University Park, PA For the application of low-friction quasicrystalline surface coatings, it is important to understand the interaction between hydrocarbon lubricants and quasicrystals. We are studying the surface of an Al13Co4 alloy, which is an approximant of the Al-Ni-Co quasicrystal. We have performed a low-energy electron diffraction (LEED) experiments of this complex surface (movie, left). An extensive LEED I(E) analysis ( 77 beams, 20,000 eV) is underway to determine its surface structure. This will provide input for the analysis of adsorption experiments. Xe Benzene The first adsorption tests on this surface used Xe as a prototypical adsorbate. The 1st Xe atoms to adsorb appear to have the symmetry of the substrate and may occupy the “holes” in the structure (right). The multilayer Xe appears to form a bulk-like structure, but which aligns and matches with the substrate structure in one direction. The complete analysis is in progress. These studies will be extended to smaller gases, like Ar or Kr, in order to gain insight into the effect of size on the ordering, before beginning the study of hydrocarbons on this surface.