[en] Heating of grazing incidence mirror surfaces by absorbed soft X-rays from a synchrotron beamline has been studied numerically to evaluate resultant displacements of the thermally loaded surface. Subsequent ray-tracing analysis has provided to corresponding change in optical performances. This procedure has been applied in particular to a thermally loaded prefocussing ellipsoidal mirror to be used in a high-spectral-resolution soft-X-ray beamline in the U2 undulator beamline of ELETTRA, and ultrahigh brightness synchrotron radiation facility under construction in Trieste. Various cooling geometries have been investigated. A detailed analysis of the results indicates deterioration of imaging properties beyond the present fabrication tolerances only at extreme irradiation levels. (orig.)

[en] We have exploited the possibility of obtaining SiC by annealing at selected increasing temperatures cluster-assembled carbon films deposited in situ by a supersonic beam onto Si(1 0 0)-(2x1) substrates. We measured the evolution of the valence bands and of the Si 2p and C 1s core level spectra to monitor the thermal induced effects in the atomic concentrations and the electronic structure at the interface. Our results indicate that at the interface Si-C bonds are already formed at 700 deg. C, a temperature that is significantly lower (∼50 deg. C) than found in literature by using other C-based precursors for SiC growth on Si surfaces. Supersonic carbon cluster beam deposition seems to be promising for the growth of SiC films on Si surfaces with improved interface quality

[en] The ability to produce cell patterning through precise surface engineering has stimulated the development of cellular bioassays that offer new insights on the mechanisms of cell adhesion, proliferation, differentiation and molecular signaling pathways. Here we describe a simple micropatterning technique combining supersonic cluster beam deposition of nanostructured titania films on bovine serum albumin functionalized substrates. A standard lift-off process enables us to generate complementary micropatterns of hydrophobic bovine serum albumin (cell-repellent) and hydrophilic nanostructured TiO_x (cell-adhesive). We demonstrate the selective PC12 cell adhesion and growth on biocompatible nanostructured TiO_x. We also observed that these functional micropatterned substrates promote a considerable enhancement of cell attachment and proliferation

[en] Synchrotron radiation-based experimental techniques are largely employed for the characterization of the reactivity of finite size systems; in particular, X-ray absorption spectroscopy (XAS) is a suitable tool to shed light on the local electronic structure and chemical status of atoms in nano-objects, as it is very sensitive to the local bonding environment of the probed site. In supported clusters intrinsic properties and reactivity are largely distorted and obscured by the changes imposed by the growth procedure and by the influence of the substrate, so the attainability of experiments on free clusters reacting with species in the gas phase is a primary goal in the development of cluster science. In this paper we report a proof of principle of the applicability of gas phase XAS technique to titanium and titanium oxide, hydride and hydrate systems. Experiments are performed by coupling a pulsed microplasma cluster source (PMCS) with a third generation synchrotron light source, and measuring the intensity of the electron yield coming from the interaction of VUV photons with the clusters seeded in a supersonic beam. (orig.)

[en] Fullerene-like MoS_2 and WS_2 nanoparticles can be used as building blocks for the fabrication of fluid and solid lubricants. Metal dichalcogenide films have a very low friction coefficient in vacuum, therefore they have mostly been used as solid lubricants in space and vacuum applications. Unfortunately, their use is significantly hampered by the fact that in the presence of humidity, oxygen and moisture, the low-friction properties of these materials rapidly degrade due to oxidation. The use of closed-cage MoS_2 and WS_2 nanoparticles may eliminate this problem, although the fabrication of lubricant thin films starting from dichalcogenide nanoparticles is, to date, a difficult task. Here we demonstrate the use of supersonic cluster beam deposition for the coating of complex mechanical elements (angular contact ball bearings) with nanostructured MoS_2 and WS_2 thin films. We report structural and tribological characterization of the coatings in view of the optimization of tribological performances for aerospace applications. (paper)

[en] Nanostructured carbon and carbon-TiO_x films produced by supersonic cluster beam deposition have been characterized by spatially resolved (0.5 μm lateral resolution) photoemission spectroscopy with synchrotron light. We have found that pure and TiO_x-containing nanostructured carbon is modified under high flux UV exposure showing the onset of a metallic character near the Fermi level. We have studied the spectroscopic features, the spatial confinement, and the kinetics of this metallization process of the irradiated regions. This effect allows one to write metallic patterns in the TiO_x-containing films with a submicrometric resolution and with a fast kinetic

[en] Nanostructured cubic zirconia is a strategic material for biomedical applications since it combines superior structural and optical properties with a nanoscale morphology able to control cell adhesion and proliferation. We produced nanostructured cubic zirconia thin films at room temperature by supersonic cluster beam deposition of nanoparticles produced in the gas phase. Precise control of film roughness at the nanoscale is obtained by operating in a ballistic deposition regime. This allows one to study the influence of nanoroughness on cell adhesion, while keeping the surface chemistry constant. We evaluated cell adhesion on nanostructured zirconia with an osteoblast-like cell line using confocal laser scanning microscopy for detailed morphological and cytoskeleton studies. We demonstrated that the organization of cytoskeleton and focal adhesion formation can be controlled by varying the evolution of surface nanoroughness. (paper)

[en] Nanostructured zirconium dioxide (zirconia) films are very promising for catalysis and biotechnological applications: a precise control of the interfacial properties of the material at different length scales and, in particular, at the nanoscale, is therefore necessary. Here, we present the characterization of cluster-assembled zirconia films produced by supersonic cluster beam deposition possessing cubic structure at room temperature and controlled nanoscale morphology. We characterized the effect of thermal annealing in reducing and oxidizing conditions on the crystalline structure, grain dimensions, and topography. We highlight the mechanisms of film growth and phase transitions, which determine the observed interfacial morphological properties and their resilience against thermal treatments.

[en] We investigated the electrical transport properties of nanostructured carbon and carbon/titanium oxide nanocomposite films produced by supersonic cluster beam deposition and irradiated by highly focused vacuum UV photon beam. We have observed a relevant increase of the density of states at Fermi level, suggesting that the films acquire a 'metallic' character. This is confirmed by the increment of the conductivity of four orders of magnitude for pure nanostructured carbon films and at least eight orders of magnitude for films containing 9 at. % of titanium. A partial reversibility of the process is observed by exposing the modified films to molecular oxygen or directly to air. We demonstrate the capability of writing micrometric conductive strips (2-3 μm width and 60 μm length) and controlling the variation of the conductivity as a function of the titanium concentration

[en] The electronic structure of cluster assembled nanostructured TiO₂ thin films has been investigated by resonant photoemission experiments with photon energies across the Ti L_2,3 edge. The samples were produced by supersonic cluster beam deposition with a pulsed microplasma cluster source. The valence band shows resonance enhancements in the binding energy region between 4 and 8 eV, populated by O 2p and hybridized Ti 3d states, and in the region about 1 eV below the Fermi level associated with defects related Ti 3d states. The data show that in as-deposited films Ti atoms are mainly fully (sixfolds) coordinated to oxygen atoms in octahedral symmetry and only a small fraction is in a broken symmetry environment. Since resonant photoemission is closely linked to the local electronic and structural configurations around the Ti atom, it is possible to correlate the resonant photoemission intensity and lineshape with the presence of defects of the films and with the degree of hybridization between the titanium and oxygen atoms