In order to study phase transitions at interfaces of liquid metallic alloys, spectroscopic ellipsometry was employed in the energy range 0.7 eV ≤ hv ≤ 3.2 eV. The complex dielectric function ε = ε1+ iε2of binary gallium-bismuth alloys was measured at bismuth concentrations 0 ≤ xBi≤ 0.28 and up to 621 K above the critical demixing temperature, 535 K. The character of the ε1-spectra undergoes a pronounced change from Ga-like to Bi-like behavior when the bismuth concentration in the liquid phase exceeds xBi= 0.085 which corresponds to the monotectic triple point. This change is interpreted as interfacial wetting of the gallium rich phase by a liquid bismuth rich phase.
Nattland, D., Müller, S. C., Poh, P. D., & Freyland, W. (1996). Wetting phenomena at the liquid-vapor interface of gallium-bismuth alloys studied by spectroscopic ellipsometry. Journal of Non-Crystalline Solids, 205–207(2), 772–775. https://doi.org/10.1016/S0022-3093(96)00305-5