Evidence of Two Kinds of Two-Dimensional Adsorbed Fluids by Mobility Measurements

Abstract

The diffusion coefficient of a mobile C${\mathrm{H}}_{4}$ submonolayer adsorbed on graphite (0001) is systematically measured by quasielastic neutron scattering. Its behavior with coverage is used to distinguish clearly two kinds of adsorbed fluids; a two-dimensional liquid and a two-dimensional liquid an a two-dimensional hypercritical fluid.