A new preparation is reported which, for the first time, results in a thin, crystalline SiO2 film on a Mo(112) single crystal. The procedure consists of repeated cycles of silicon deposition and subsequent oxidation, followed by a final annealing procedure. AES and XPS have been used to control film stoichiometry. LEED pictures of high contrast show a hexagonal, crystalline SiO2 overlayer with a commensurate relationship to the Mo(112) substrate. The wetting of the substrate by the film has been investigated by LEED, XPS and TDS, revealing that the film covers the substrate completely.

Photosubstitution and/or photoisomerization in cis-[Ru(bpy)2(py)2](PF6)2 and trans-[Ru(bpy)2(4-Etpy)2](PF6)2 or the molecular assemblies cis-[Ru(bpy)2(MQ+)2](PF6)4 and trans-[Ru(bpy)2(MQ+)2](PF6)4 are greatly inhibited in the rigid matrixes poly(methyl methacrylate) (PMMA) films and silica sol−gel monoliths. There can also be profound changes in photophysical properties as illustrated below for emission from cis-[Ru(bpy)2(py)2](PF6)2 in CH3CN and in the silica sol−gel.

For Pd clusters on γ-Al2O3 epitaxially grown on NiAl(110) the lattice constant has been determined as a function of the cluster size by evaluating patterns induced by double diffraction involving the NiAl substrate and the cluster lattice. Similar to results reported previously for platinum and tantalum clusters on the same substrate (Surf. Sci. 1997, 391, 27; Surf. Sci. 1998, 413, 192), we observe a reduction of the distances within the lattice with decreasing cluster size. The highest observed reduction is 5% for clusters with a diameter of about 12 Å. Within the limits of the experimental errors the reduction of the lattice distances is isotropic. Although the samples have been exposed to air prior to investigation, the clusters are only weakly oxidized as concluded from XPS data.

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