Interfacial segregation and wetting transition in fluid binary metallic mixtures

Abstract

First indications of wetting transitions in alkalimetal‐alkalihalide solutions have been obtained in previous optical studies. In order to study this transition continuously as a function of temperature and composition along the coexisting curve and in the homogeneous phase we have started SHG‐measurements on these systems at the fluid‐sapphire interface. First results of this experiment in comparison with the ellipsometric results will be presented. On the other hand, in order to exclude influences of the substrate on the interfacial behaviour we have investigated the liquid‐vapour interface in the liquid alloy Ga‐Bi (metallic system with miscibility gap) by spectroscopic ellipsometry. The main interest concentrates on possible discontinuous changes of the optical constants at the interface with varying composition and temperature. First results are presented.