Temperature-dependent behaviour of capillary waves at Hg-vapour and Hg-HgO interfaces

Free and oxidized surfaces of liquid mercury have been studied by means of light scattering from thermally excited capillary waves. The temperature dependence of the wave peak frequency at the free Hg surface reveals a negative derivative of the surface tension d gamma/dT. This phenomenon is related to the spatial distribution of quasi-free electrons being much more strongly temperature dependent than the local surface ordering recently revealed at the Hg-vapour interface. The frequency omega(T) observed at the Hg-HgO interface displayed two essentially different tendencies, according to the thickness of the oxide film.