The X-Ray Facility in Chemistry-Physics


Views of the X-Ray Laboratory

The X-Ray Facility houses a Nonius kappaCCD sealed-tube diffractometer (Mo), and a Bruker-Nonius X8 Proteum (Cu), which was obtained with funds from the MRI program of the National Science Foundation. At installation it was one of the world's most powerful diffractometers for chemical crystallography in an academic chemistry department.


KappaCCD diffractometer (above left) and X8 Proteum (above right)

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 a destructive phase transition may force data collection at a higher temperature. Fortunately the control box on the left makes changing temperature quick and easy.


Low-temperature machinery

High-quality stereo microscopes are an essential feature of any well-equipped crystallography laboratory. We have two main microscopes, an Olympus SZX12 and an SZX9. The SZX12 has a specially designed low-profile light source, allowing both transmitted and reflected light, and is equipped with easily interchangeable polarizers and filters. We also have extra add-on objectives and higher-power eyepiece lenses to aid in crystal selection and microsurgery. The SZX9 has an Olympus ILL-D base, again allowing reflected and transmitted light. Rotating stages are an absolute necessity for crystal inspection. Our preferred stage for the SZX12 (below right) is an old Supper film measuring device. It is large, flat and easily positioned, and easier to use than ordinary rotary microscope stages. The SZX9 stage was custom made in our superb machine shop.


Olympus stereomicroscopes

The video camera shown in the picture above middle (attached to the SZX12) is invaluable for teaching crystal manipulation techniques. For high quality stills we have interchangeable lens high-resolution digital cameras (Olympus OMD-EM1 and PEN-EP2), which take pictures like these:


We are well equipped for crystallographic computation with a half dozen or so Linux (including custom builds) and Macintosh computers for data collection, structure solution, refinement, and for the Cambridge Structure Database. We even have a couple of Windows machines (hidden behind Linux firewalls where they hopefully cannot cause damage).