MgCl 2 and C 2 H 5 OH form complexes over a wide range of C 2 H 5 OH to MgCl 2 molar ratios. MgCl 2 (C 2 H 5 OH) x adducts prepared over a wide composition range, x ) 0.47 to 6, have been studied by ultraviolet Raman spectroscopy. These studies indicate the breaking of the Mg-Cl bonds at x g 2. The Raman shift of the O-H stretch shifts in the 3230-3480 cm -1 range as the C 2 H 5 OH to MgCl 2 molar ratio is altered and thus, it can be used to monitor the MgCl 2 (C 2 H 5 OH) x composition. It is suggested that the presence of the peak at 683 cm -1 may be attributed to the totally symmetric breathing mode of Mg-O octahedra, reinforcing the structure analysis of MgCl 2 (C 2 H 5 OH) 6 .

Temperature-programmed desorption (TPD) of physisorbed mesitylene molecules has been used as a nondestructive surface probe to distinguish the surface adsorption sites of model Ziegler-Natta polymerization catalysts. A MgCl2-supported titanium chloride film (TiClx/MgCl2) was fabricated on an inert gold substrate by codeposition of Mg metal and TiCl4 from the gas phase. The mesitylene TPD probe revealed two types of surface adsorption sites. The dominant site was attributed to the basal plane of these halide crystallites. The minor site could be tentatively attributed to a defective structure at the basal plane boundaries or other crystal planes. Due to the chlorine termination nature of the catalyst surface, the metal ions under the chlorine layer could not be differentiated directly with the physisorbed mesitylene molecules. However, the mesitylene TPD profile was able to monitor compositional changes in the outermost chlorine layer accompanying the reaction of the catalyst film with the triethylaluminum cocatalyst, electron beam irradiation of the film surface, and diffusion of bulk chlorine to minimize the number of defect sites.

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We report the preparation of ZnO nanocrystals embedded in a SiO2 matrix formed using sequential zinc and oxygen ion implantations. The optical absorption spectra and photoemission spectra of zinc implanted and zinc/oxygen coimplanted silica show that the first zinc implantation produces zinc clusters and that the subsequent oxygen implantation following the zinc implantation rearranges the distribution of zinc and oxygen ions at an atomic level. While thermal annealing of Zn only implanted silica leads to the formation of Zn nanocrystals, thermal annealing of zinc/oxygen coimplanted silica promotes the growth of ZnO nanocrystals. The absorption and photoluminescence spectra show that ZnO nanocrystals form in an amorphous SiO2 matrix and that their systematic change as a function of annealing temperature corresponds to the typical correlation between the increase of particle size and a redshift in near-band-edge emission.

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X-ray photoelectron spectroscopy (XPS) and Temperature ProgrammedDesorption (TPD) have been used to investigate the surface structure of model heterogeneous catalysts in ultra-high vacuum (UHV). UV-Raman spectroscopy has been used to probe the structure of bulk model catalysts in ambient and reaction conditions. The structural information obtained through UV-Raman spectroscopy has been correlated with both the UHV surface analysis and reaction results.The present day propylene and ethylene polymerization catalysts (Ziegler-Natta catalysts) are prepared by deposition of TiCl 4 and a Al(Et) 3 co-catalyst on a microporous Mg-ethoxide support that is prepared from MgCl 2 and ethanol. A model thin film catalyst is prepared by depositing metallic Mg on a Au foil in a UHV chamber in a background of TiCl 4 in the gas phase. XPS results indicate that the Mg is completely oxidized to MgCl 2 by TiCl 4 resulting in a thin film of MgCl 2 /TiCl x , where x 2 = 2, 3, and 4. To prepare an active catalyst, the thin film of MgCl 2 /TiCl x on Au foil is enclosed in a high pressure cell contained within the UHV chamber and exposed to ~1 Torr of Al(Et) 3 .TPD of physisorbed mesitylene molecules has been used as a nondestructive surface probe to distinguish the surface adsorption sites of this model Ziegler-Natta polymerization catalyst. The mesitylene TPD probe revealed two types of surface adsorption sites. The dominant site was attributed to the basal plane of these halide crystallites. Other sites present in lower concentration could be attributed to a defect structure at the basal plane boundaries with other crystal planes. Due to the chlorine termination of the catalyst surface, the metal ions under the chlorine layer could not be differentiated directly with the physisorbed mesitylene molecules. However, the mesitylene TPD profile was able to monitor compositional changes in the outermost chlorine layer accompanying a) the reaction of the catalyst film with the triethylaluminum cocatalysts, b) electron beam irradiation of the film surface, and c) diffusion of bulk chlorine to the surface to minimize the number of defect sites.Microporous samples of Mg-ethoxide Ziegler-Natta catalyst supports were made from MgCl 2 and ethanol. Samples with an ethanol-to-MgCl 2 molar ratio (x) from 0.47 to 6 were studied by UV-Raman spectroscopy. These studies indicate the breaking of Mg-Cl bonds at molar ratios > 2. At x = 6, the octahedral coordination of the Mg