Silicon nanostructures embedded in an amorphous matrix have been synthesized by Pulsed Laser Deposition (PLD) at room temperature. The structural and optical properties of the materials were tailored by varying deposition parameters; attention has been devoted to the nanoscale morphology of the Si layers which has been varied from compact to open-porous by changing background gas (Ar) pressure (1-100 Pa). An adopted simple-minded strategy of a compact Si layer deposited on top of nanostructured layers showed to reduce quite successfully ex-situ oxidation. Raman spectroscopy suggests that as deposited samples are mainly constituted by amorphous silicon with nanocrystals (NCs) inclusions. The results indicate that the average size of the Si NCs varies in the range 2-6 nm. Photoluminescence (PL) responses are found to be strictly dependent on morphology and strengthen up the idea of the quantum confinement effect in the obtained nanostructured material. The results are interpreted in terms of particle size distribution, crystallinity and partial surface oxidation of the silicon nanostructures.

With the aim of addressing the material gap issue between model and real systems in heterogeneous catalysis, we exploited Pulsed Laser Deposition (PLD) to produce Pd clusters supported on ultrathin alumina films (Pd/Al2O3/NiAl(001) and Pd/Al2O3-x/HOPG). The structural properties have been investigated by in situ Scanning Tunneling Microscopy (STM) in ultra high vacuum (UHV). At first, Pd clusters were deposited by evaporation and by PLD on Al2O3 surfaces grown by thermal oxidation of NiAl(001). The system shows thermal stability up to 650 K. By PLD we deposited Pd clusters with a good size control obtained by varying the background gas pressure and the target-to-substrate distance. We then realized a

Pd/Al2O3-x/HOPG system where both Pd clusters and the alumina film are produced by PLD showing that, by exploiting the same deposition technique, it is possible to synthesize both a model system addressable by in situ STM and a thick film (∼100 μm) closer to realistic systems.

The structural evolution of polytetrafluoroethylene (PTFE) crystalline polymer latex films is studied at hundreds nanometer length scale by atomic force microscopy and Brillouin light scattering. In a controlled sintering process the transition is observed from the original particle distribution towards a ‘fibrillar’ structure of crystalline regions embedded in a disordered matrix. This transition is accompanied by a cross-over from localized acoustic excitations to propagating acoustic phonons, related to mesoscopic elastic properties. After sintering, a ‘mark’ of the original particulate structure persists, suggesting that filming of crystalline polymers may be analogous to sintering of ceramic powders. Films of crystalline polymers can thus be exploited as model systems to study the elasto-optical properties of granular and disordered media.

The structural evolution of polytetrafluoroethylene (PTFE) crystalline polymer latex films is studied at hundreds nanometer length scale by atomic force microscopy and Brillouin light scattering. In a controlled sintering process the transition is observed from the original particle distribution towards a ‘fibrillar’ structure of crystalline regions embedded in a disordered matrix. This transition is accompanied by a cross-over from localized acoustic excitations to propagating acoustic phonons, related to mesoscopic elastic properties. After sintering, a ‘mark’ of the original particulate structure persists, suggesting that filming of crystalline polymers may be analogous to sintering of ceramic powders. Films of crystalline polymers can thus be exploited as model systems to study the elasto-optical properties of granular and disordered media.

The elastic constants of thin Diamond-Like Carbon (DLC) films supply important information, but their measurement is difficult. Standard nanoindentation does not directly measure the elastic constants and has strong limitations particularly in the case of hard thin films on softer substrates, such as tetrahedral amorphous carbon on Si. Surface acoustic waves provide a better mean to investigate elastic properties. Surface Brillouin scattering (SBS) intrinsically probes acoustic waves of the wavelength which is appropriate to test the properties of films in the tens to hundreds of nanometers thickness range. SBS can be used to derive all the isotropic elastic constants of hard-on-soft and soft-on-hard amorphous carbon films of different kinds, with thickness down to less than 10 nm. The results help to resolve the previous uncertainties in mechanical data. The Young's modulus of tetrahedral amorphous carbon (ta-C) turns out to be lower than that of diamond, while the moduli of hydrogenated ta-C (ta-C:H) are considerably lower than those of ta-C because of the weakening effect of C-H bonding.

This work presents the first results of a study aimed at better understanding the elastic behaviour of hard coatings produced by various techniques. This is important also in view of the need to be able to control the level of internal stresses, particularly in PVD coatings. It is well known that in extreme cases excessive internal stress can lead to complete film destruction. We devote this paper to reactively magnetron sputtered TiN, one of the most widely used compounds. Thin TiN films of different compositions were deposited on Si substrates and characterized by SEM, AES, XRD and Brillouin light scattering.