High-resolution x-ray scattering measurements: 1. Surfaces

X-ray scattering investigations of surfaces and interfaces in soft-condensed matter are reviewed. Both high-resolution structural determinations in the direct space and investigations of fluctuations with long-range correlations requiring a high resolution in the Fourier space are discussed. All the scattering cross-sections for diffraction or diffuse scattering are derived within a unified frame, and the experimental aspects related to their measurement are discussed in detail. The general principles are illustrated by various examples of studies of the liquidvapour interface, Langmuir and Langmuir-Blodgett films, wetting films, polymer films, liquid crystals and liquid-liquid interfaces.