Structural and surface investigations of aluminas and aluminum containing materials

Aluminum containing materials such as aluminas, clays, and zeolites are of interest due to their interesting chemical and catalytic properties. Previous research has included the use of infrared spectroscopy to study the surface of these materials. The results from this research has allowed for the postulation of the surface structure. Since for a majority of these materials it is difficult to form single crystals, most structural information is based on refinement of x-ray powder patterns. The observed diffraction patterns can be quite broad due to the surface morphology of the materials. This lack of resolution can result in ambiguous assignments of the structural components present.; Since in these systems the surface of the material is of interest, I used 1H-27Al cross-polarization to study those aluminum sites that are located on the surface. With 1H- 27Al cross-polarization, magnetization is transferred from surface protons to adjacent aluminum sites. These measurements have resulted in the first observation of a five-coordinate site in the transition aluminas studied. The use of heteronuclear correlation (HETCOR) spectroscopy allows for the observation of connectivities between the proton sites and their associated aluminum sites. These techniques, however, are still limited in resolution due to the broad lines that are still present.; Previously, in order to increase resolution, MQMAS was implemented. Because of the low population of surface sites, standard MQMAS is unable to distinguish these sites from those in the bulk. To increase the sensitivity of the surface sites, cross-polarization was incorporated into the MQMAS pulse sequence. The resulting CPMQMAS experiment has enabled the observation of distinct surface sites.