Thermodynamics of Short Chain Perfluoroalkanes Adsorbed on the Surfaces of the Graphite Basal Plane and MgO (100)

Molecular adsorption of short-chain linear perfluoroalkanes was studied by volumetric isotherm and by molecular dynamics simulation. Isotherms of perfluoroethane, perfluoropropane, and perfluorobutane gas were measured on clean surfaces of the graphite basal plane nanometer-scale cubic magnesium oxide (100). Each system was measured over a range of temperatures, and thermodynamic determinations of the entropies, enthalpies, and heats of adsorption were determined as a result. Potential phase transitions between the surface structures were identified, and the constant-coverage heats of adsorption for each system were determined. Comparisons to molecular dynamics simulations provided guidance in the assignment of phase diagrams, giving insights to the microscopic structural behaviors of the systems.