Self-aligned silver nanocolumns embedded in amorphous Al2O3 matrix are produced by alternate pulsed laser deposition at room temperature in a single step process. The morphology and the spatial distribution have been investigated by standard, high resolution, and scanning transmission electron microscopy. Polycrystalline nanocolumns having diameters close to 3nm and heights up to 7nm are all oriented perpendicular to the substrate surface. The self-alignment of the nanocolumns is the consequence of the deposition of consecutive layers of Ag nanoparticles using the first layer as template for the ordered growth of the nanocolumns. Control over the density, diameter and height of the nanocolumns is achievable by tailoring the deposition sequence.

Ge nanoparticles embedded in an oxide matrix have been obtained by (a) steam thermal oxidation at 650 • C of polycrystalline SiGe layers and (b) deposition of discontinuous Ge films/SiO 2 multilayers by low pressure chemical vapour deposition at 390 • C and thermal annealing at 700 • C. These two approaches are compared in terms of the composition and size of the nanoparticles and the luminescence properties of the structures. In both cases violet luminescence peaking at 3.1 eV is detected. The origin of this emission in both types of structures is the same and it will be related to defects at the interface between the nanocrystalline Ge and the dielectric matrix. Thinking about future applications, the second approach is found to be much more attractive from the technological point of view, even considering that the first one gives a more intense luminescence emission, since the structure can be fabricated in a single-run process; these structures are currently being investigated to improve their luminescence emission.

The luminescence emission of structures containing Ge nanocrystals embedded in a dielectric matrix obtained by dry and wet oxidation of polycrystalline SiGe layers has been studied as a function of the oxidation time and initial SiGe layer thickness. A clear relationship between the intensity of the luminescence, the structure of the sample, the formation of Ge nanocrystals and the oxidation process parameters that allows us to select the appropriate process conditions to get the most efficient emission has been established. The evolution of the composition and thickness of the growing oxides and the remaining SiGe layer during the oxidation processes has been characterized using Raman spectroscopy, x-ray diffraction, Fourier-transform infrared spectroscopy, Rutherford backscattering spectrometry and transmission electron microscopy. For dry oxidation, the luminescence appears suddenly, regardless of the initial SiGe layer thickness, when all the Si of the SiGe has been oxidized and the remaining layer of the segregated Ge starts to be oxidized forming Ge nanocrystals. Luminescence is observed as long as Ge nanocrystals are present. For wet oxidation, the luminescence appears from the first stages of the oxidation, and is related to the formation of Ge-rich nanoclusters trapped in the mixed (Si and Ge) growing oxide. A sharp increase of the luminescence intensity for long oxidation times is also observed, due to the formation of Ge nanocrystals by the oxidation of the layer of segregated Ge. For both processes the luminescence is quenched when the oxidation time is long enough to cause the full oxidation of the Ge nanocrystals. The intensity of the luminescence in the dry oxidized samples is about ten times higher than in the wet oxidized ones for equal initial thickness of the SiGe layer.

Amorphous SiGe nanoparticles embedded in an oxide matrix, with controlled composition, diameter of a few nm, located in the same plane and with an areal density above 10 12 cm -2 have been deposited by Low Pressure Chemical Vapour Deposition in a single run using a conventional hot wall reactor. The deposited nanoparticles were crystallized by Rapid Thermal Annealing. X-ray Reflectometry and Rutherford Backscattering Spectrometry, with models developed for these purposes, have been tested as fast and reliable analytical tools to determine the composition, size and areal density of the nanoparticles. Transmission Electron Microscopy has been used to validate the results and to study the nanoparticle crystallization.

Several complexes with a [2 × 2] grid structure have been obtained by the self-assembly of different copper(I) salts and ligands of the type 4,6-bis(pyrazol-1-yl)pyrimidine containing different substituents on the heterocycles. The main goal has been to evaluate the influence over the solid state and solution behavior of the functionalization of the pyrimidine ring with a primary amino substituent. The molecular and crystalline structures of some derivatives have been determined by X-ray diffraction. The grids contain two open voids formed by pairs of ligands facing one another on opposite sides of the grid in a somewhat divergent manner. One counteranion is hosted in each void interacting through hydrogen bonds and anion-π interactions. The presence of the amino group that points toward the inside of the cavity dominates the interactions in the void and apparently determines the orientation of the hosted counteranion and that of the ligands. With the exception of the derivative with chloride as the anion, the grid structure is preserved in solution (NMR and UV-vis) and some cation-anion interaction, increased by the presence of the amino group, exists also in solution (DOSY experiments). The experiments of anion interchange performed in solution indicate that a higher stability is found for the host-guest aggregates with OTs(-) (p-Me-C(6)H(4)SO(3)) and NO(3)(-). While for these anions a 1:2 stoichiometry is reached, for the rest of the anions tested (ReO(4)(-), OTf(-), and PF(6)(-)), only weaker 1:1 complexes are formed. Computational studies support the presence of anion-π interactions.