Triple-point wetting and surface melting of oxygen films adsorbed on graphite

Abstract

Neutron diffraction experiments on multilayer oxygen films on graphite have been carried out between 30 and 55 K. A compound solid-liquid film is observed in the range 40--48 K, exhibiting properties consistent with surface melting. The quantity of liquid in this range varies as ln(${\mathrm{T}}_{\mathrm{t}}$-T). This behavior ceases when the thickness of the liquid component reaches that of the film itself, giving rise to the ``metastable liquid'' phase of the triple point wetting process.