Gas–Surface Interactions on Quasicrystals

Gas–surface interactions have been a topic of much study for the past 50 years, both to increase our knowledge of fundamental interactions in matter and to enhance the many useful processes that occur at surfaces. In studies of the fundamental behavior of rare gases at quasicrystal surfaces, it was demonstrated that under certain conditions the gas films adopt the quasicrystalline structure, and under other conditions, they adopt their natural periodic close-packed structure. In light of the interesting frictional properties of quasicrystal surfaces, this raised the question of whether the use of lubricants with quasicrystal surfaces might actually raise their coefficient of friction rather than reduce it. In this review, we describe first the studies of rare gases that resulted in a phenomenological rule that describes whether film growth on a quasicrystalline surface results in a periodic or an aperiodic structure. We then describe the studies of hydrocarbon adsorption on the same surface, which is found to follow the same rule, implying that large hydrocarbons, such as those typically used in lubricants, may not improve the lubricity of quasicrystal surfaces.