An ellipsometric study of the surface freezing of liquid alkanes

The surface freezing of alkane/air interfaces was investigated by ellipsometry and surface tension measurements. It is observed as a small jump in the ellipsometric signal. This shift can be explained by the transition from an isotropic liquid surface to a well-ordered monolayer only through a fortituous cancellation of layering and anisotropy effects. Therefore, an alternative model is discussed which interprets the surface freezing as a transition from a nematic-like molecular ordering at the interface above the surface melting temperature to a smectic-like ordering below.