UK X-Ray Facility


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The X-Ray Facility houses a recently installed (2017) dual-microsource Bruker D8 Venture κ-axis diffractometer (Mo & Cu) with large-area 'Photon-II' CMOS detector, and a Bruker-Nonius X8 Proteum (Cu) rotating-anode diffractometer, each with low-temperature devices. Both instruments were obtained with funds from the MRI program of the National Science Foundation (grants CHE-0319176 and CHE-1625732). The X8 Proteum was rebuilt in 2017, with a 'Pt-135' CCD detector, 'K3' goniometer, and newer multilayer optics.

The low-temperature attachments deliver a constant, low-velocity flow of cold nitrogen gas over the crystal. Low temperature has many benefits for X-ray structure determination, including better quality data in less time than for room-temperature work, and the ability to handle highly reactive compounds with minimal fuss. We typically collect data at 90K, but occasionally destructive phase transitions necessitate higher temperatures (83-500K is possible).

Stereo microscopes are an essential feature of any well-equipped crystallography laboratory. We have two main microscopes: Olympus models SZX12 and SZX9. The SZX12 has a custom built low-profile light source, for both transmitted and reflected light. The SZX9, which is usually housed in the Director's office, has a modified Olympus ILL-D base, again allowing reflected and transmitted light. Both scopes have easily interchangeable polarizers and filters. Extra objectives and higher-power eyepiece lenses aid in crystal selection and microsurgery for the tiniest crystals. Precise, rotating stages are a necessity for crystal inspection. The stage used for the SZX12 (below, first) is an old Supper film-measuring device. It is large, flat, easily positioned, and demonstrably superior to ordinary rotary microscope stages. The SZX9 stage was custom made in our superb machine shop.

The video camera (above middle) is invaluable for teaching crystal manipulation techniques. For still pictures we have high-resolution digital cameras (Olympus OMD-EM1 and PEN-EP2), which attach via bayonet mount to the microscopes to allow pictures like these:

The facility is well equipped for computations, with a half dozen or so Linux (including COTS, OEM, and custom builds) and Macintosh computers for data collection, structure solution, refinement, and for the Cambridge Structure Database. The diffractometers are driven by a couple of Windows boxes, which are hidden from the outside world behind Linux firewalls, where they hopefully cannot cause any damage.