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Biological methods for mosquito larvae control are completely biodegradable and have null or limited effects on nontarget organisms. However, commercially available products have a low residual activity, with the consequent need for multiple applications that inevitably increase costs and the risk of resistance phenomena insurgence. Smart delivery systems made of hydrogels proved their efficacy in increasing the action duration of biolarvicides up to several months, but the lack of an efficient baiting mechanism to strongly attract the target pest remains a problem in practical applications. In this work, we investigated two novel hydrogel-based formulations of completely natural composition for baiting and killing larvae of

We present the synthesis, fabrication and electro-mechanical characterization of a novel electro-responsive hydrogel based on Na-4-vinylbenzenesulfonate (Na-4-VBS) that can operate as a fast response bending actuator in a low voltage regime (0.2–5 V), in NaCl aqueous solutions. The bending speed can reach values up to 22°/s at 3 V and of 2.7°/s at 1 V. The responsive behavior of the benders was observed in physiological environments as well, such as phosphate buffer solution (PBS) and Dulbecco’s Modified Eagle’s Medium (DMEM) and exhibited similar performance. The material is a co-polymer comprising also hydroxyethyl methacrylate (HEMA) and acrylonitrile (AN), to confer high hydrophilicity to the structure and to enhance its elastic properties. According to the swelling and electro-mechanical testing results, the electrically driven deformation of the hydrogels was interpreted as a dynamic osmotic equilibrium effect taking place at the interface between the polymer and the surrounding medium, induced by the free ionic species migration throughout the polymer. This material constitutes a promising solution for the design and production of highly performing soft underwater actuators and biomimetic smart systems that can be controllably operated at the macro and mesoscale in fluids of biological interest, with minimal power consumption and below the standard potential of water electrolysis.

The use of synthetic gel matrices prepared with poly(vinyl-alcohol) (PVA) cross-linked by glutaraldehyde (GTA) contributed to enhance the interest toward radiochromic Fricke gel (FG) dosimeters. As it occurs in several chemical dosimeters, the response of PVA-GTA Fricke gels could be affected by temperature. Aim of this work is to study the dependence of the dosimetric properties of PVA-GTA Fricke gel dosimeters both on the irradiation temperature and on temperature changes possibly occurring between the irradiation and readout phases. Such effects were investigated by means of magnetic resonance imaging (MRI) and optical absorbance (OA) measurements. The results did not reveal any significant dependence of the sensitivity of the dosimeters on the irradiation temperature in the investigated interval 20°C-35°C. By contrast, auto-oxidation phenomena confirmed to be a critical aspect for FG dosimeters, also in case of use of PVA matrix. The extent such phenomena, that might impair the accuracy of dose estimations, proved to critically depend on the temperature at which FG dosimeters are subjected before and after irradiation, as well as on the duration of possible thermal-stress.

Soft robotics is an emerging field targeting at the development of robotic bodies and architectures characterized by flexibility, adaptability, and motility typical of that of biological systems. The use of electroactive ionic polymer–metal nanocomposites able to reversibly deform in response to low-intensity electric fields constitutes a promising solution for the implementation of actuators into soft robots. Currently, the use of this class of nanocomposites is hampered by several drawbacks, mainly related to the mismatch between the mechanical properties of the polymer and the metallic electrodes compromising their stability and resilience upon cyclic deformation. Here, we report and discuss on the use of supersonic cluster beam implantation (SCBI) as an effective strategy for the fabrication of soft electroactive ionic polymeric nanocomposite actuators. SCBI relies on the use of supersonically accelerated beams of neutral metal nanoparticles that can be aerodynamically collimated and directed onto a polymeric target to generate thin nanostructured metal layers physically interpenetrating with the polymer. Soft electroactive actuators based on engineered ionogel and ionogel-based hybrid nanocomposites provided with monolithically integrated cluster-assembled gold electrodes will be discussed. These systems can undergo long-term bending deformation in a low-voltage regime, due to the nanostructured electrode resilience. The use of cluster-assembled nanostructured electrodes opens new opportunities for the high-throughput manufacturing of soft ionic actuators with excellent mechanical resiliency, high-performance actuation, and high durability.

We present a room-temperature bonding technique which enables the sealing of micromolded water-swollen poly-2-hydroxy ethyl methacrylate (PHEMA)-based hydrogel modules to thermoplastic and elastomeric platforms. The core mechanism of the proposed method is to favor the formation of hydrogen bonds at the interface between the surface-reactive hydrated hydrogel components and the functionalized hydrophobic materials, by contacting the polymeric layers via a mild compression. Plasma oxygen and silanization processes using 3-amino-propyl trimethoxy silane have been optimized to generate surface hydroxyl functionalities on poly-methyl methacrylate (PMMA) and poly-dimethyl siloxane (PDMS) platforms which can react with the OH groups’ enriched surface of the microstructured PHEMA. The resulting microsystems can operate in a continuous perfusion mode while being soaked in water to keep the hydrogel hydrated. The method could also be applied to bond PHEMA thin layers (300 μm thick) to PMMA and PDMS microfluidic components. The sealing properties of the produced devices were demonstrated by liquid leakage tests and further validated by hydration–dehydration cycles of the systems and by monitoring methylene blue diffusion through the hydrogel matrix at the modules interface. The presented technique is suitable for cells-based hybrid materials microfluidic devices rapid prototyping.

We report the synthesis, fabrication and characterization of a hybrid hydrogel/cellulose nanocomposite, which exhibits high-performance electro–mechanical underwater actuation and high sensitivity in response to electrical stimuli below the standard potential of water electrolysis. The macromolecular structure of the material is constituted by an electroactive hydrogel, obtained through a photo-polymerization reaction with the use of three vinylic co-monomers: Na-4-vinylbenzenesulfonate, 2-hydroxyethylmethacrylate, and acrylonitrile. Different amounts (from 0.1% to 1.4% w/w) of biodegradable cellulose nanocrystals (CNCs) with sulfonate surface groups, obtained through the acidic hydrolysis of sulphite pulp lapsheets, are physically incorporated into the gel matrix during the synthesis step. Freestanding thin films of the nanocomposites are molded, and their swelling, mechanical and responsive properties are fully characterized. We observed that the embedding of the CNCs enhanced both the material Young's modulus and its sensitivity to the applied electric field in the sub-volt regime (down to 5 mV cm−1). A demonstrator integrating multiple actuators that cooperatively bend together, mimicking the motion of an electro-valve, is also prototyped and tested. The presented nanocomposite is suitable for the development of soft smart components for bio-robotic applications and cells-based and bio-hybrid fluidic devices fabrication.

A microfluidic system with an inserted membrane assembled using mechanical fastening process is described. The membrane is made of a biocompatible water swollen poly(2-hydroxyethyl methacrylate) (PHEMA) hydrogel thin film as a sealing component. The hyperelastic characteristics of PHEMA membrane under the compression during fastening are investigated through numerical simulations, including strain and Von Mises stress distribution, and potential fracture in correlation with the microchannel's geometry and dimensions. To validate the modeling, the experiments have also been conducted to visualize the deformation induced in membrane and internal stress distribution using 3D optical measuring system. The results from this study have revealed the implications in connection with the mechanical behavior of the PHEMA membranes in the assembly of microfluidic system through mechanical fastening technique. This will ultimately assist to produce a guideline for the optimum design of microchannels in the uses of PHEMA membranes and associated assembly process. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014, 52, 485–495

Engineered silver nanoparticles (AgNPs) are among the most used nanomaterials in consumer products, therefore concerns are raised about their potential for adverse effects in humans and environment. Although an increasing number of studies in vitro and in vivo are being reported on the toxicity of AgNPs, most of them suffer from incomplete characterization of AgNPs in the tested biological media. As a consequence, the comparison of toxicological data is troublesome and the toxicity evaluation still remains an open critical issue. The development of a reliable protocol to evaluate interactions of AgNPs with surrounding proteins as well as to assess their colloidal stability is therefore required. In this regard, it is of importance not only to use multiple, easy-to-access and simple techniques but also to understand limitations of each characterization methods. In this work, the morphological and structural behaviour of AgNPs has been studied in two relevant biological media, namely 10 % FBS and MP. Three different techniques (Dynamic Light Scattering, Transmission Electron Microscopy, UV–Vis spectroscopy) were tested for their suitability in detecting AgNPs of three different sizes (10, 40 and 100 nm) coated with either citrate or polyvinylpyrrolidone. Results showed that UV–Vis spectroscopy is the most versatile and informative technique to gain information about interaction between AgNPs and surrounding proteins and to determine their colloidal stability in the tested biological media. These findings are expected to provide useful insights in characterizing AgNPs before performing any further in vitro/in vivo experiment.

In this study, we present a microdevice coated with titanium dioxide for cells and particles separation and handling. The microsystem consists of a pair of planar interdigitated gold micro-electrode arrays on a quartz substrate able to generate a traveling electric completed with a microfabricated three-dimensional glass structure for cell confinement. Dielectrophoretic forces were exploited for both vertical and lateral cell motions. In order to provide a biocompatible passivation layer to the electrodes a highly biocompatible nanostructured titanium dioxide film was deposited by supersonic cluster beam deposition (SCBD) on the electrode array. The dielectrophoretic effects of the chip were initially tested using polystyrene beads. To test the biocompatibility and capability of dielectrophoretic cell movement of the device, four cell lines (NIH3T3, SH-SY5Y, MDCK, and PC12) were used. Separation of beads from SH-SY5Y cells was also obtained.

We report about a novel class of electroactive nanocomposites designed to perform spring-like actuation at low applied voltages. These systems are based on the impregnation of plain paper with a highly conductive ionogel, interpenetrating nanostructured conducting electrodes are printed on the paper/ionogel substrate by supersonic cluster beam deposition. Due to the structure and mechanical properties of the paper substrates, helix-shaped actuators can be obtained by coiling strips of the nanocomposites, thus enabling the production of electroactive components exhibiting motion up to two millimeters with a polarization of 5 V. Our approach constitutes a promising solution for the development of adaptive soft robotic architectures and smart flexible systems with bio-inspired motility.

Nanostructured titanium dioxide (ns-TiO2) films were grown by supersonic cluster beam deposition method. Transmission electron microscopy demonstrated that films are mainly composed by TiO2 nanocrystals embedded in an amorphous TiO2 phase while their electronic structure was studied by photoemission spectroscopy. The cluster assembled ns-TiO2 films are expected to exhibit several structural and chemical defects owing to the large surface to volume ratio of the deposited clusters. Ultraviolet photoemission spectra (hv = 50 eV) from the valence band unveil the presence of a restrained amount of surface Ti 3d defect states in the band gap, whereas Ti 2p core level X-ray photoelectron (hv = 630 eV) spectra do not manifestly disclose these defects.

We have investigated the influence on adhesion and proliferation of NIH 3T3 fibroblasts of the surface morphology of cluster assembled carbon films deposited by Supersonic Cluster Beam Deposition. Nanostructured carbon films exhibit a multi-scale morphology, which resembles the surface structure of the extracellular matrix, and possess a high specific area, while being relatively smooth at all scales. Correlations between measured morphological parameters and adaptive cell response have been brought out. High specific area and smoothness appear to conceivably favour both the early attachment of plated cells and the long-term survival of adherent cells. Moreover, nano-structured carbon films affect the cells morphology as well as the extension and the number of the focal contacts.

Nanostructured carbon thin films can be grown by deposition of cluster beams produced in supersonic expansions. By using a pulsed microplasma cluster source and by exploiting aerodynamic focusing effects typical of supersonic expansions, the structure and the properties of the films can be controlled by varying the cluster mass distribution prior to deposition. Nanocomposite films can be produced by co-depositing carbon clusters and metallic nanoparticles. The films have been characterized by various spectroscopic techniques and tested in view of applications for field emission, supercapacitors, gas sensing. The possibility of patterning cluster-assembled carbon films by shadow masking or by ultraviolet photon irradiation suggests interesting perspective for the integration of nanostructured carbon films on microfabricated devices and for the production of components for an all-carbon electronics.

We have developed a method for the quantitative evaluation of the chemisorbed fraction of hydrogen in nanostructured carbon films using Near Edge X-ray Absorption Spectroscopy (NEXAFS). In the carbon K-edge spectrum the peak related to carbon bonded to hydrogen is assumed to be correlated with the amount of hydrogen bonded to carbon. This assumption is supported by a comparative analysis of gas-phase hydrocarbons obtained via Electron Energy Loss Spectroscopy (EELS). We applied the method to nanostructured carbon (ns-C) films synthesized by supersonic cluster beam deposition. The evaluated quantity of chemisorbed hydrogen in different samples exposed to molecular hydrogen (pressure of 0.12 MPa, for 3 hours at room temperature) is ∼1.5 wt.%.

A multi‐scale investigation of nanostructured carbon films has been performed by means of inelastic light scattering (Raman and Brillouin scattering). Carbon films with different nano‐ and mesostructure have been deposited from supersonic cluster beams in a low energy deposition regime by exploiting aerodynamic focusing effects. Acoustic phonon propagation in the porous amorphous structure, where disorder acts as a damping factor, is investigated by Brillouin scattering. Depending on the nano‐ and meso‐structure, acoustic phonons can either propagate along the medium, which acts as an elastic continuum at the meso‐scale (i.e., hundreds of nm), or turn to overdamped oscillations localized by the structural disorder. Nevertheless, we show that it is always possible to measure the elastic constants of thin and porous films, when other techniques (e.g., nano‐indentation) become critical. At the nano‐scale, Raman scattering measurements show the typical structure of an amorphous carbon, where the stru...

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)-(2 x 1) 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 degreesC, a temperature that is significantly lower (approximate to 50 degreesC) 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.

Near-edge X-ray absorption fine structure (NEXAFS) measurements have been made on carbon nitride films containing as much as 44 at.% of nitrogen. The films have been synthesized by dual ion beam deposition (IBD) bombarding a carbon target with low-energy nitrogen ions at varying nitrogen beam energies and substrate temperatures ranging from the liquid nitrogen temperature up to 400°C. The structural changes induced by the reduction of the temperature have been previously investigated [Hammer et al., J. Vac. Sci. Technol. A 15 (1) (1997) 107; Baker et al., Surf. Coat. Technol. 97 (1997) 544]. The transition from a predominantly sp2/sp3 CN amorphous arrangement to a more polymer-like structure has been confirmed and more deeply examined by X-ray absorption spectroscopy. In particular, for samples deposited at liquid nitrogen temperature, a relevant reduction of sp2 CC fraction has been detected. Moreover, the condensation on the growing film surface of hydrogen containing species (i.e. HCN) has been well identified by the appearance of the CH∗ peak.

The preferential sputtering of S from bulk MoS2 standard samples exposed to 3 keV Ar+ ion bombardment has been studied by XPS. The MoSx stoichiometry decreases from MoS2 to MoS1.12 with a concomitant reduction in the Mo 3d5/2 binding energy from 229.25 to 228.35 eV. The altered layer extends to a depth of 3.8 nm and is proposed to consist of a single amorphous MoSx phase in which Mo has a varying number of nearest neighbour S atoms. Using peak positions alone it is possible to determine the MoSx stoichiometry to an accuracy of x±0.1 from a plot of MoSx stoichiometry against (Mo 3d5/2–S 2p3/2) binding energy. The results are of strong current interest for coating analysis applications as MoS2 is a compound capable of providing low friction properties when incorporated into hard coatings.

Bombarding a carbon target with low-energy nitrogen ions causes the release of neutral carbon atoms (physical sputtering) and volatile carbon nitride compounds (chemical sputtering) with relative yields dependent on the energy of the nitrogen beam. The chemically sputtered species are volatile and can be condensed on the substrate by reducing its temperature. Carbon nitride films have been deposited at varying nitrogen beam energies and substrate temperatures in a dual ion beam deposition chamber. Films were grown both with and without the presence of an additional assisting nitrogen beam. Reduction of the substrate temperature in conjunction with low sputter beam voltages (

The thermally agglomerated Au/Si(111) interface has been studied by means of laterally resolved photoemission by exploiting the ultra-high brightness of the ELETTRA synchrotron radiation source. The interface has been evaluated in terms of chemical maps and core level spectra acquired from selected points of the specimen surface. The variety of distinct chemical environments local to element-specific sites has thereby been clarified with an unprecedented level of resolution at both the islands and the two-dimensional superstructure terminating the Si crystal.

The electrical properties of cluster-assembled nanostructured palladium oxide $({\text{ns-PdO}}_{x})$ thin films grown by supersonic cluster beam deposition have been characterized by means of a customized ac current-sensing atomic force microscope. Scanning impedance microscopy is shown to provide a deep picture of the electrical properties of thin nanostructured interfaces even in the case of very soft and poorly adherent films. In particular, the dielectric constant of ${\text{ns-PdO}}_{x}$ can be quantitatively determined as well as its $I\text{\ensuremath{-}}V$ characteristics. Moreover, the measurement of the tip-sample parasitic capacitance can be exploited to probe the overall mesoscale conductive character of thin films and to give a complementary and more precise view of the oxidation of ${\text{ns-PdO}}_{x}$ obtained by x-ray photoemission spectroscopy.

Amorphous carbon films with $sp\text{\ensuremath{-}}s{p}^{2}$ hybridization, produced by supersonic cluster beam deposition, shows the presence of both polyynic and cumulenic species [L. Ravagnan et al., Phys. Rev. Lett. 98, 216103 (2007)]. Here, we present an in situ Raman characterization of the low-frequency vibrational region $(400\char21{}800\text{ }{\text{cm}}^{\ensuremath{-}1})$ of $sp\text{\ensuremath{-}}s{p}^{2}$ films at different temperatures. We report the presence of two peaks at 450 and $720\text{ }{\text{cm}}^{\ensuremath{-}1}$. The lower frequency peak shows an evolution with the variation of the $sp$ content and it can be attributed, with the support of density functional theory simulations, to bending modes of $sp$ linear structures. The peak at $720\text{ }{\text{cm}}^{\ensuremath{-}1}$ does not vary with the $sp$ content and it can be attributed to a feature in the vibrational density of states activated by the disorder of the $s{p}^{2}$ phase.

Poly(amidoamine)s are biocompatible biodegradable polymers, which can be easily functionalized with a number of bioactive and biomimetic compounds. Co-polymerization of these polymers with 4-aminobutyl guanidine (agmatine) leads to an RGD mimicking structure. Hydrogels based on this structure showed an enhanced cell adhesion and could be chemically linked to a glass substrate to create a bioadhesive support for cell growth. Preliminary optimization and cell adhesion tests on Madin-Darby Canine Kidney cells were performed, both on functionalized and non-functionalized structures, with promising results.

Fullerene-like MoS2 and WS2 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 MoS2 and WS2 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 MoS2 and WS2 thin films. We report structural and tribological characterization of the coatings in view of the optimization of tribological performances for aerospace applications.

The main scientific issue hindering the development of tissue engineering technologies is the lack of proper vascularization. Among the various approaches developed for boosting vascularization, scaffold design has attracted increasing interest over the last few years. The aim of this article is to illustrate a scaffold design strategy for enhancing vascularization based on sacrificial microfabrication of embedded microchannels. This approach was combined with an innovative poly(ether urethane urea) (PEUtU) porous scaffold to provide an alternative graft substitute material for the treatment of tissue defects. Fluorescent and chemiluminescent imaging combined with computed tomography were used to study the behavior of the scaffold composition within living subjects by analyzing angiogenesis and inflammation processes and observing the variation in x-ray absorption, respectively. For this purpose, an IntegriSense 680 probe was used in vivo for the localization and quantification of integrin α v β 3 , due to its critical involvement in angiogenesis, and a XenoLight RediJect Inflammation Probe for the study of the decline in inflammation progression during healing. Overall, the collected data suggest the advantages of embedding a synthetic vascular network into a PEUtU porous matrix to enhance in vivo tissue integration, maturation, and regeneration. Moreover, our imaging approach proved to be an efficient and versatile tool for scaffold in vivo testing.

In this work we show that supersonic cluster beam deposition is a viable method for the synthesis of nanocrystalline metal/carbon composites. By assembling carbon and metallic clusters seeded in a supersonic beam, we have grown films consisting of metal nanoparticles embedded in a nano-structured carbon matrix. Samples containing 3d transition metals (Ti, Ni) and noble metals (Au, Pd, Pt) with different metal abundances, particle size and dilution have been characterized by transmission electron microscopy. The influence of different metals on the structure of the carbon matrix has been investigated. Spatially resolved ultraviolet photoemission electron spectroscopy showed substantial surface oxidation of 3d transition metal clusters. On a micrometric scale, the spatial distribution of the metallic nanoparticles appeared to be homogeneous.

Nanostructured carbon films consisting of sp chains (polyynes and polycumulenes) embedded in an sp 2 matrix are grown using supersonic carbon cluster beam deposition in ultrahigh vacuum at room temperature. All the specimens have been analyzed by in situ Raman spectroscopy. The use of different excitation wavelengths (532 and 632.8 nm) confirms the presence of distinct carbynoid species. Chemical stability of the sp species has been studied by exposing the as-deposited films to 500 mbar of H 2 , He, N 2 , and dry air. Gas exposure produces an exponential decay of the carbynoid fraction slightly affecting the sp 2 component. Helium, hydrogen, and nitrogen do not chemically interact with the sp chains whereas oxygen reacts with the carbynoids species causing their fast and almost complete destruction. The films have been also thermally annealed at 20°, 100°, 150°, and 200°C. The amount of carbynoid species is rapidly and strongly reduced at temperature larger than room temperature. The relevance for material science and interstellar chemistry of the production of a bulk form of carbon where sp and sp 2 hybridizations coexist is addressed.

We employed chemical vapor deposition (CVD) from powder precursors aiming at large-area growth of molybdenum ditelluride (MoTe2) thin films, with controlled allotropic 2H and 1T′ phases. This major...

In this work, we have examined Fe-Mn-Si-Cr alloys possessing a good shape memory effect due to a high Mn content (28 wt pct). The addition of Cr (5 wt pct) was made in order to give fairly good corrosion resistance to the alloy. But we have verified that even in moderately corrosive environments, the presence of chromium does not bear any passivation. On the other hand, we have found that the alloy can acquire corrosion resistance by means of the formation of a Mn-depleted surface layer obtained by heating the alloy at high temperature (⋍ 1050 °C) in air. This modified layer forms since manganese is selectively oxidized with respect to the other components. The adhesion of this layer is maintained even under severe stress if the thickness of the modified region does not exceed 20 µm. Under this limit, the shape memory characteristics of the alloy are not affected, and at the same time, the specimen acquires properties of passivity comparable with one of the most common austenitic stainless steels at the presence of the same environmental conditions.

Carbon nitride films (CNx) have been deposited by sputtering a graphite target with nitrogen ions. Films were grown both with and without the presence of an assisting focused N2 ion beam. The sputter beam voltage was varied between 150 and 1500 V and the applied assisting beam voltage from 80 to 500 V. The substrate was held at fixed temperatures between 80 and 673 K. The coatings were characterized with respect to their electrical, optical, and structural properties. The nitrogen content was measured by x-ray photoelectron spectroscopy (XPS) and a maximum nitrogen concentration of 44 at. % was obtained for a nonassisted sample deposited at 140 K. The chemical structure was investigated by XPS and Fourier transform infrared spectroscopy. Reduction of the substrate temperature in conjunction with low sputter beam voltages (

The use of clusters as elemental building blocks can open routes toward the fabrication of a new class of nanostructured solids and devices. We report the synthesis of nanostructured films using supersonic cluster beam deposition. A new type of cluster source based on microplasma ablation has been developed. This allows a substantial improvement in terms of deposition rate and control on cluster mass distribution. These achievements make supersonic cluster beams a useful tool in the arena of cluster assembling of materials. We have applied this technique to the growth of nanostructured carbon thin films. The structure and morphology of the films can be controlled by varying the cluster mass distribution prior to deposition. Deposition conditions affect the surface roughness and the onset of scale-invariant morphology on a dimension domain extending from the nanometer up to the micrometer. The cluster beam deposition method shows very promising features in view of the large scale growth of nanostructured films with novel functional and structural properties. The patterning of three-dimensional nanostructured objects is also demonstrated.

The first stages of aggregation of low energy deposited carbon clusters on Ag(1 1 0) surface have been observed in situ by scanning tunnelling microscopy (STM). Sub-monolayer coverages of the substrate at room temperature have been obtained by using a supersonic neutral cluster beam with a mass distribution centered at an average of 900 atoms/cluster. We observe that clusters are able to diffuse on the surface and along steps, and organise themselves in compact islands principally located at step edges. Size of supported islands ranges from a few nm up to 40 nm. A statistical analysis based on several STM images shows that the island size follows a lognormal distribution law. Possible mechanisms involved in the diffusion and coalescence of carbon clusters on metallic surfaces are discussed.