Facilities and Centers
X-Ray Crystallography
Researchers in the Department of Chemistry and Biochemistry have developed one of the most advanced and well-equipped X-ray crystallography facilities in the world. The Molecular Structure Facility maintains three state-of-the-science CCD-based single-crystal diffractometers, a CCD-based powder diffractometer and two Gunier powder cameras. This facility allows exceptionally fast access to detailed structural characterizations of crystalline chemical compounds.
Two of the CCD single-crystal diffractometers are based on a 3-circle Eulerian geometry, while the third instrument is designed around a 4-circle Kappa geometry. The fourth circle of the latter instrument allows the flexibility to access any reflection and is useful for highly specialized experiments. Nearly all experiments in the facility are performed at low-temperature using a cooled nitrogen gas stream, 100 K for most samples.
The powder diffractometer and Guinier cameras provide a fast, efficient means to verify chemical phases of materials and also to determine if results from single-crystal analyses are consistent with the composition of the bulk solids.
A necessary prerequisite to data collection is crystal selection. Because the crystals are small, ca. 0.008 mm3, they are examined and selected using a stereomicroscope. The facility is equipped with two polarizing stereomicroscopes. One, with a magnification range of 10x to 96x, is outfitted with a digital video camera to allow digital photography of specimens under bright-field, reflected, or polarized illumination.
Students are encouraged to learn to operate the instruments and to critically analyze and interpret the data so that they may perform their own experiments under the supervision of the facility director, Professor Bruce Noll. Training is provided through a combination of coursework and hands-on training.
