Anomalous temperature dependence of the surface tension and capillary waves at a liquid-gallium surface

The temperature dependence of the surface tension ( T ) of liquid gallium is studied theoretically and experimentally using light scattering from capillary waves. The theoretical model based on the Gibbs thermodynamics relates / T to the surface excess entropy density - S . Although capillary waves contribute to the surface entropy with a positive sign, the effect of the dipole layer on S is negative. Experimental data collected at a free Ga surface in the temperature range from 30 °C to 160 °C show that / T changes sign near 100 °C.