Curved Crystal Microfocus X-ray Monochromator

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This Proposal requests funding for a curved crystal microfocus monochromator which will replace the standard flat graphite monochromator of our Bruker Smart Apex 2 Molybdenum diffractometer. The upgrade will provide an X-ray "hot spot" at the crystal, resulting in up to 7 times the diffracted intensity from very small single crystals, allowing researchers to determine molecular and solid-state structures from samples as small as ca. 0.000004 mm3. The Applicant has consistently pushed the limits of what can be achieved in a chemistry X-ray laboratory. The existing instrumentation and sample preparation techniques have been configured to tackle a wide range of challenging problems. The increased brilliance of the X-ray source will allow the Applicant to obtain molecular structures that were previously unattainable for a large percentage of his air- and thermally sensitive compounds which are, sometime, aggressive oxidizers, and to produce more precise structural models in less time and more economically. In addition to providing access to more and better quality molecular structures, this upgrade will also permit the Applicant and other users of the McMaster X-ray facility (MAX) to obtain high-resolution diffraction data, including detailed diffuse and incommensurate scattering. These scattering features will allow the modeling of short range structural modifications and intergrowth of phases, two factors which can drastically alter the physical properties of materials. One of the mandates of the MAX facility is the hands-on training of graduate students, postdoctoral fellows, and faculty in the use of diffraction methods to solve structural problems. Graduate level courses are offered in the theory and practice of single-crystal and powder diffraction techniques, and course projects generally result in publications. Consequently, new applications and capabilities are constantly being developed and disseminated from the MAX Facility. A state-of-the art microfocus X-ray source with the enhanced capabilities it imparts to the existing Mo diffractometer would also provide training in X-ray crystallography that is up-to-date. The identical upgrade has recently appeared in labs in Canada and has proven to be a worthwhile investment.