W0112

Small Crystal Studies Using a SMART System at Daresbury. William Clegg, University of Newcastle upon Tyne and CCLRC Daresbury Laboratory, Warrington WA4 4AD, UK

The world's oldest dedicated synchrotron radiation source is now producing many new structural results for very small crystals in a wide variety of chemistry and materials science research areas. Commissioning has recently been completed on a single-crystal diffraction station at Daresbury SRS and it is oversubscribed in its first public allocation period. While crystals which are very small in all dimensions may benefit from the higher brilliance of more modern synchrotron sources, such samples with sizes down to 10 or 20 microns have been successfully examined at Daresbury. The facility is particularly useful for crystals which are thin needles and plates, giving a low overall scattering volume with a moderate maximum dimension. Such samples form a high proportion of the problems brought to Daresbury for solution. Rapid data collection is achieved with a high incident X-ray flux and a CCD area detector diffractometer. High-temperature and low-temperature data collection procedures are routine, the latter being particularly important in many cases.

The facility has already been exploited by a large number of academic and commercial researchers from the U.K. and other countries; it has been used, among other applications, in the study of zeolites and other microporous materials, supramolecular assemblies, cage and cluster molecules, organometallics and coordination compounds, dyestuffs, catalytic materials, and pharmaceuticals. Examples will be presented.

On-going developments include improved X-ray optics for very small crystals, software enhancements, and an integrated approach using single-crystal and powder diffraction techniques.