816 EXPERIMENTAL METHODS AND INSTRUMENTATION J. Appl. Cryst. (1997). 30, 816-821 Time-resolved Small-Angle X-ray Scattering Combined with Wide-Angle X-ray Scattering WIM BRAS a'c AND ANTHONY J. RYAN b'c aDUBBLE CRG/ESRF, Netherlands Organisation for Scientific Research (NWO), c/o ESRF, BP 220, F38042 Grenoble CEDEX, France, bUniversity of Manchester Insitute of Science and Technology, Grosvenor Street, Manchester, England, and CDaresbury Laboratory, Warrington WA4 4AD, England. E-mail: bras@esrf.fr (Received 23 July 1996; accepted 21 January 1997) Abstract The high X-ray intensity of synchrotron radiation (SR) beamlines makes it possible to perform time-resolved small-angle X-ray scattering (SAXS) experiments. The information that can be obtained by collecting the wide- angle diffraction pattern simultaneously not only increases the information content of an experiment but also increases the reliability of the time-correlations between SAXS and WAXS (wide-angle X-ray scatter- ing) patterns. This is a great advantage for experiments with a time resolution below the level of 1 s per frame. With appropriate instrumentation, this is a time domain that is routinely accessible for a large group of research fields. This has had a considerable impact upon the understanding of fundamental aspects of phase trans- formations. Not only fundamental processes but also more applied fields have benefited from these develop- ments. In polymer research this has led to a situation in which it has become possible to simulate materials processing techniques on-line. With the advent of third- generation synchrotron-radiation sources (e.g. ESRF, APS, Spring8), it has become possible to develop SAXS/WAXS beamlines that will open up new research opportunities by utilizing the higher intensity, the tuneability and the higher collimation offered by these SR sources. However, some of the instrumentation limits in detector and sample environments that have become apparent in research on second-generation synchrotron-radiation sources still have not been appropriately addressed, which means that in some fields it will not be possible to take full advantage of the superior X-ray beam quality that third-generation syn- chrotrons can offer. A way in which these instru- mentation limits can be overcome is discussed, and the instrumentation for a new bending-magnet beamline at the ESRF is used as an example. 1. Introduction The simultaneous recording of time-resolved small- angle scattering (TRSAXS) and wide-angle scattering © 1997 International Union of Crystallography Printed in Great Britain - all rights reserved (TRWAXS) patterns has become increasingly popular in the last decade owing to the increasing number of SR beamlines suitable for this type of work (Bark & Zachmann, 1993; Bras et al., 1993; Hsiao, Gardner, Wu & Chu, 1993). The pioneering work on time-resolved scattering experiments on polymers by the group of Zachmann in Hamburg especially deserves to be men- tioned (Zachmann & Gehrke, 1986). For strongly scat- tering samples, the increased availability of sensitive electronic detectors even allows collection of TRXAXS/ WAXS data when a rotating-anode generator is used as the X-ray source (Laggner & Mio, 1992). The detection of the WAXS pattern was originally seen as a useful extension to a beamline essentially designed for SAXS experiments, but this has changed to a situation in which there are several beamlines, either in the design phase or already operational, that are used specifically for SAXS/ WAXS experiments. There are several fields where it is essential to study the structural changes on different length scales after a sample has been perturbed. For instance, in semi- crystalline polymers the large-scale morphological units (spherulites, lamellae) combined with the molecular crystallographic packing determine the macroscopic properties of the material. To be able to correlate accurately the development of these two after a tem- perature quench of the sample from the melt is of importance to understand the underlying physics driving the formation of the final structure. This is important for both a fundamental understanding and for manufactur- ing purposes (e.g. Wutz, Bark, Cronauer, Drhrmann & Zackmann, 1995). In lipid membrane research a similar argument applies with the large-scale structures being the membrane interdistance or undulations and the short scale structure the positions of the lipids inside the membrane (e.g. Caffrey, 1989; Cunningham, Bras, Lis & Quinn, 1994). For noncyclic processes, SAXS/WAXS experiments can now routinely be performed on time- scales down to 0.5 s per frame and still render data that can be used for quantitative purposes. To perform these experiments on a timescale that is compatible with Journal of Applied Crystallography ISSN 0021-8898 © 1997