Abstract
The surface of a crystal is the place where the crystal interacts with its environment. Knowledge of the atomic structure of a solid-liquid interface is important to understand the different processes occurring at the surface, such as crystal growth. Both the structure at the solid side and on the liquid side of the interface deviate from the bulk structure. The crystal surface can show relaxations and even a reconstruction of the outermost surface layer. The liquid at the surface `feels' the periodic potential of the crystal and can adopt some of its ordering. The first chapters deal with two ionic crystals, KDP and KBC, in contact with an ultra-thin water layer. The liquid structure at the interface of KDP crystals shows two important features. The crystal is covered with two ice-like layers of water molecules that are tightly bound to the surface and occupy well defined positions on the surface. These ice-like layers are covered by a diffuse water layer in which the first layer of water molecules still shows some ordering. Liquid metal monolayers on a Ge(111) surface are described in the last chapters. The structure of the solid-liquid interface of Sn/Ge(111) is investigated as a function of temperature. Our analysis shows that the liquid Sn exists as a dynamic, 2D-layer with Sn atoms residing preferentially on sites imposed by the Ge(111) lattice. The structure of the liquid Sn layer gradually changes with temperature from more solid-like to more liquid-like. Both the phase transitions and the structure of the Pb/Ge(111) system are investigated. The critical exponents of the 2D phase transition of the beta phase correspond to the values expected for mean field behavior. This indicates that the Pb atoms have long range interaction potentials.
