ABSTRACT

Liquids are in many ways similar to solids, but due to their nature and their lack of long-range order, there are some special considerations both experimentally and theoretically to be taken into account. Of special interest are liquid surfaces and inter faces, where often longrange ordering effects are observed. The reason is that a flat smooth surface is in effect in a one-dimensional (1D) ordered state and competes against the disorder in the liquid’s bulk. Interfacial properties and phenomena of liquid and in particular liquid/liquid interfaces are recognized as having great importance in the fields of organics [1], polymer science [2], bioscience [3], and electrochemistry [4]. Many of these systems have been neglected up to now due to demanding technical and instrumental requirements. In this chapter, the principles of liquid interfaces will be introduced along with the X-ray scattering theory appropriate for liquids and liquid interfaces. Experimental considerations for X-ray scattering investigations at liquid interfaces will be discussed, and

recent developments in this area will be considered. The theory and experimental details will be illustrated with examples at the liquidvapor interface and liquid-liquid interface.