A NEW HIGH-FLUX CHEMICAL AND MATERIALS CRYSTALLOGRAPHY STATION AT THESRS DARESBURY .1. DESIGN, CONSTRUCTION AND TEST-RESULTS

A new single-crystal diffraction facility has been constructed on beam line 9 of the SRS at Daresbury Laboratory for the study of structural problems in chemistry and materials science. The station utilizes up t o 3.8 mrad horizontally from the 5 T wiggler magnet which can he focus ed horizontally and vertically. The horizontal focusing is provided by a choice of gallium-cooled triangular bent Si (111) or Si (220) monoc hromators, giving a wavelength range from 0.3 to 1.5 Angstrom. Focusin g in the vertical plane is achieved by a cylindrically bent zerodur mi rror with a 300 mu m-thick palladium coating. The station is equipped with a modified Enraf-Nonius CAD-4 four-circle diffractometer and a Si emens SMART CCD area-detector system. High- and low-temperature facili ties are available to cover the temperature range from about 80 to 100 0 K. Early results on test compounds without optimization of the beam optics demonstrate that excellent refined structures can be obtained f rom samples giving diffraction patterns too weak to be measured with c onventional laboratory X-ray sources, fulfilling a major objective of the project.