The soft condensed matter (SCM) group is composed of the public beamlines ID02, ID10A, ID10B, ID13 and the CRG beamlines BM02, BM26 and BM32. Soft condensed matter science addresses questions on microstructure, kinetics, dynamics and rheology of complex and nanostructured materials. Similar activities are pursued at many other ESRF beamlines, which shows that borders with neighbouring disciplines are transparent. In the future, one can expect that the SCM beamlines will increasingly address problems in nanoscience and biotechnology.

The following highlights give an overview on the diversity of topics investigated at the SCM group beamlines, which shows that both scientific applications and methodological approaches are evolving rapidly. The increasing use of surface-sensitive techniques is particularly interesting as it provides more collaborative possibilities for the SCM group.

X-ray photon correlation spectroscopy (XPCS) is a technique for probing bulk dynamics, which has been pioneered at the Troika beamline. Two methodological advances are reported from ID10A, which provide new and exciting opportunities. Thus Gutt et al. and Madsen et al. (page 58) have used grazing-incidence XPCS on ID10A to study capillary wave propagation in water/glycerol mixtures. Among the possible future applications are fluctuating lipid membranes, which are currently studied by static diffuse scattering techniques (see below). XPCS has also been extended up to ª 20 keV by Thurn-Albrecht et al. (page 59), for a model colloidal silica suspension. The use of higher energies reduces absorption and allows thicker samples and longer acquisition times. This method should therefore have an impact on studies of polymeric and biological samples, which are particularly "photon hungry".

Recently, anomalous small-angle X-ray scattering (ASAXS) has found new applications in soft condensed matter. At the ID02 beamline, N. Dingenouts et al. (page 60) have exploited this technique to address one of the long-standing issues in the physics of polyelectrolytes, namely the spatial correlation of the counterions with the macroions. In another important development at ID02 during the year, the high count-rate RAPID gas detector from the Daresbury Laboratory [1] was employed for a series of millisecond time-resolved experiments involving muscle diffraction and fast kinetics in solution. This exercise allowed the first combination of the high brilliance of a third generation source with a state-of-the-art photon-counting detector for sub-millisecond time-resolved small-angle diffraction experiments.

The use of microbeam techniques has been further developed at ID13. Thus understanding the local structure of high-performance fibres is of considerable technological importance. Davies et al. (page 61) have studied the local structure of different brands of poly(p-phenylene benzobisoxazole) fibres as a function of uniaxial stress. Differences in skin-core structures and crystallite orientation could be related to spinning and postprocessing conditions. Grazing-incidence small-angle scattering (GISAXS) techniques have been extended by Roth et al. to micrometre-sized beams (page 63). This "mGISAXS"-technique allowed them to characterise a lateral gradient of nanometric gold clusters on a substrate. The future use of submicrometre beams is of particular interest for applications in constrained environments such as thin fibres, channels or heterogeneous surfaces.

The setup available at ID10B has been developed in particular for studies of organic or biological surfaces/interfaces by surface-sensitive techniques. Dürr et al. (page 64) have investigated the growth mechanism of diindenoperylene molecules by a combination of atomic-force microscopy, specular X-ray reflectivity and diffuse X-ray scattering. The observed rapid roughening suggests a subtle competition between domain shape and local crystal structure. This is a particularly interesting domain of research as semiconducting organic films have promising applications in electronic devices. De Jeu et al. (page 65) report on a fundamental study of the 2D/3D transition of a single top layer of a stack of smectic layers. This grazing-incidence X-ray diffraction study aims at probing theoretical models of defect mediated melting processes.

Lipid membranes are of great interest as they might result in novel biomolecular materials. Stacks of lipid membranes on silicon at full hydration have been studied at the ID01 beamline by nonspecular, diffuse X-ray reflectivity measurements by the group of Salditt et al. (page 67). These quasi 2D-objects show a correlation of thermal fluctuations and positional parameters, which can be treated only approximately with current elasticity models. This example also emphasises the pursuit of SCM-topics at other ESRF beamlines.

C. Riekel

[1] R.A. Lewis et al., NIM A, 392(1-3), 32-41 (1997).