High-pressure single-crystal X-ray diffraction facilities on station 9.8 at the SRS Daresbury Laboratory - hydrogen location in the high-pressure structure of ethanol

A new high-pressure single-crystal diffraction facility has been constructe d on station 9.8 at the Synchrotron Radiation Source, Daresbury Laboratory, for a range of studies on a variety of systems of relevance to physics, ch emistry and materials science that would otherwise prove intractable with c onventional laboratory-based methods. The station has been equipped with a modified Enraf-Nonius CAD4 four-circle diffractometer for high-pressure stu dies which can be conveniently, and rapidly, interchanged with the Bruker S MART CCD area-detector system when more routine ambient-pressure diffractio n work is to be undertaken. This rapid change-over has been achieved by per manently mounting the CAD4 on its own jacking table, formerly used for the station's white-beam diffraction mode, which allows the alignment of the SM ART diffractometer to remain undisturbed when the CAD4 is in use. Early res ults on the test low-melting-point compound ethanol (CH3CH2OH) reveal that excellent refined structures can be obtained, including the location and re finement of the H atoms, demonstrating that one of the original, and major, objectives of the station has been accomplished.