Spherical metallic nanoparticles have been formed in ${\mathrm{SiO}}_2$ layers by 160-keV implantation of Co ions at a fluence of ${10}^{17}$ ions ${\mathrm{cm}}^{-2}.$ The implanted samples were next irradiated with $200-\mathrm{MeV}{}^{127}\mathrm{I}$ at fluences ranging from ${10}^{11}$ to ${10}^{14}$ ions ${\mathrm{cm}}^{-2}$ at room temperature. Modifications of nanoparticle size and shape were observed by transmission-electron microscopy and have been characterized by magnetic measurements at 295 and 5 K. For ${}^{127}\mathrm{I}$ fluences below ${10}^{12}$ ions ${\mathrm{cm}}^{-2},$ the nanoparticles grow in size but remain spherical. For higher fluences an anisotropic growth occurs, with elongation and the preferential easy axis seen along the incident-beam direction. The nanoparticle’s growth and deformations are attributed to thermal spike effects.

To get updated references on the structural, electronic, and vibration properties of the metastable TiO2(B) compound, infrared and Raman spectra of TiO2(B) are computed within the density functional theory framework and all active modes are assigned. Phonons and their possible coupling with the macroscopic electric fields resulting from the long-range interactions of instantaneous local dipoles (due to nuclear vibrations) in polar solids are taken into account through supercell calculations and longitudinal optical-transversal optical splitting corrections. Full structural relaxations using conventional density functional theory and hybrid functionals with localized Gaussian-type orbitals or plane-wave basis sets reveal a similar deviation of the local Ti environment compared to the TiO2(B) structural refinements reported so far. Such deviations are shown to be significant from those computed for anatase using the same method, thus yielding distinguishable spectroscopic responses for the two polymorphs.

A remarkable and unprecedented increase in catalyst selectivity in dendrimer catalysis is observed for the Pyrphos-Pd catalysed allylic amination of 1,3-diphenyl-1-acetoxypropene as a function of the dendrimer generation (with up to 64 metal sites). This steady increase in ee-values for the allylic amination is less pronounced for the poly(propyleneimine)-derived catalysts than for the corresponding palladium-PAMAM dendrimer catalysts for which an increase in selectivity from 9% ee for a mononuclear reference system to 69% ee for the Pd₆₄-dendrimer was found.