Pairing interactions and Gibbs adsorption at the liquid Bi-In surface: A resonant x-ray reflectivity study

---

DiMasi E, Tostmann H, Shpyrko OG, Huber P, Ocko BM, Pershan PS, Deutsch M, Berman LE

Abstract:
Resonant x-ray reflectivity measurements from the surface of liquid Bi22In78 find only a modest surface Bi enhancement, with 35 at.% Bi in the first atomic layer. This is in contrast to the Gibbs adsorption in all liquid alloys studied to date, which show surface segregation of a complete monolayer of the low surface tension component. This suggests that surface adsorption in Bi-In is dominated by attractive interactions that increase the number of Bi-In neighbors at the surface. These are the first measurements in which resonant x-ray scattering has been used to quantify compositional changes induced at a liquid alloy surface.