Wavelength dependence of liquid-vapor interfacial tension of Ga

The wave-vector dependence of the liquid-vapor interfacial tension of Ga, gamma(q), has been determined from diffuse x-ray scattering measurements. The ratio gamma(q)/gamma(0)=1 for q<0.05 Angstrom(-1) decreases to 0.5 near q=0.22 Angstrom(-1), and increases strongly for larger q. The observed form for gamma(q)/gamma(0) is consistent with the prediction from the Mecke-Dietrich theory when the known stratified liquid-vapor interfacial density profile of Ga and a pseudopotential based pair interaction with appropriate asymptotic (r-->infinity) behavior are used. The detailed behavior of gamma(q)/gamma(0) depends on the particular forms of both the interfacial density profile and the asymptotic falloff of the atomic pair interaction.