INTERFACIAL WETTING TRANSITIONS IN IONIC AND METALLIC FLUID MIXTURES

Recent experimental investigations of interfacial wetting phenomena in binary liquid mixtures characterized by Coulomb or screened Coulomb s hort range interactions are discussed. Wetting transitions occurring a t the fluid-wall and the fluid-vapour interface are considered focusin g on the examples of fluid alkalimetal-alkalihalide mixtures and liqui d gallium-based binary alloys at elevated temperatures. Different spec troscopic methods have been employed to probe the respective interface s, spectroscopic ellipsometry and second harmonic generation (SHG). In the case of K-KCl solutions the SHG results exhibit changes character istic of a prewetting transition in metalrich solutions implying a fir st order wetting transition at coexistence. A wetting transition is ob served for liquid Ga-Bi and Ga-Pb alloys approaching the monotectic po int at coexistence.