Structure and dynamics of tetrahalomethane adsorption on (001) surfaces of graphite and α-quartz

Molecular dynamics (MD) simulations were used to study the structural and dynamic properties of multilayer adsorption of each of three halomethanes, CF(4), CF(3)Cl, and CF(3)Br, adsorbed onto the (001) surface of either of two atomically flat but chemically and structurally different substrates (graphite and hydroxylated α-quartz) at temperatures ranging from 60 to 300 K. Analysis of the data shows a strong influence on the adsorption characteristics of these halomethane films due to the surface characteristics of the chosen substrate. In particular, the nature of the hydroxylation of α-quartz shows a striking ability to alter the affinity with which species adsorb onto its surface. This effect appears to be at least partly responsible for the differences in the orientation and packing of molecules in the first film layer as well as differences in the effect of temperature variation on phase behavior and dynamics.