Structure of multilayers on (0 0 0 1) surfaces of graphite and hydroxylated -quartz: A molecular dynamics study

We present findings from a recent molecular dynamics study of multilayer adsorption of tetrafluoromethane ( CF 4 ) onto two atomically flat but chemically and structurally different substrates: graphite (hydrophobic) and hydroxylated α -quartz (hydrophilic). Simulations in this study were carried out at temperatures in the range of 60–120 K. Subsequent analysis shows that the structure and character of the substrate surface play a large role in whether adsorbed films exhibit packing arrangements that are highly ordered or are subject to a high degree of temperature dependence. Additionally, flexible hydroxyl groups on the surface of hydroxylated α -quartz are shown to arrange themselves in a zig-zag pattern that creates an array of hexagonal domains which determine the allowed CF 4 adsorption sites.