Search

In view of the demand for high-quality thermal neutron detectors, boron films have recently attracted widespread research interest because of their special properties. In this work, we report on the deposition of boron films on silicon substrates by sub-picosecond pulsed laser deposition (PLD) at room temperature. Particular emphasis was placed on the investigation of the effect of the laser energy density (fluence) on the ablation process of the target material, as well as on the morphological properties of the resulting films. In addition, based on the study of the ablation and deposition rates as a function of the fluence, the ablation/deposition mechanisms are discussed. We show that well-adherent and stable boron films, with good quality surfaces revealing a good surface flatness and absence of cracks, can be obtained by means of the PLD technique, which proves to be a reliable and reproducible method for the fabrication of thick boron coatings that are suitable for neutron detection technology.

Analysis of the demand, of the use of the IDRIN and of new potential developments., WP2 - Pilot scheme for the management of a distributed research infrastructure offering harmonised, interoperable and integrated services

Summarization: This study describes the fabrication of ultrafast laser-induced periodic nanostructures on Nickel sheets and their use as cathodes in alkaline electrolysis. For the first time, to the best of our knowledge, laser-nanostructured Ni sheets were used as cathode electrodes in a custom-made electrolysis cell at actual, Hydrogen producing conditions, and their efficiency has been compared to the untreated Nickel sheets. The electrochemical evaluation showed higher Jpeaks, lower overpotential, and enhanced double-layer capacitance for the nanostructured electrode. A decrease in the Tafel slope was also found for the nanostructured electrode. The hydrogen production efficiency was found to be 3.7 times larger for the laser-nanostructured Nickel electrode, which was also confirmed by current-time measurements during electrolysis. Also, a novel approach is proposed to improve the stability of the current density during electrolysis and, therefore, the hydrogen production process by about 10%. Presented on: International Journal of Hydrogen Energy

Deposition of Au nanoparticles (NPs) through UV ultra-short-pulse laser ablation in vacuum is a methodology suitable for obtaining high purity supported plasmonic NPs with a superb adherence to both planar and patterned substrates. Furthermore, the peculiarity that upon sub-picosecond laser irradiation NPs form directly within the target leads to narrow and controlled size-distribution. While extensive literature theoretically models phase changes and pressure relaxation of metal targets under sub-picosecond irradiation, the evolution of the nanostructured deposit through different ablation regimes is poorly documented experimentally. In this paper, besides modeling the temporal evolution of electron and lattice temperature following sub-picosecond laser pulse irradiation of Au bulk at the threshold ablation fluence (0.1 J/cm2), we report an accurate statistical, morphological and structural characterization of the AuNP distributions as a function of the laser fluence tuned from 0.1 to 3 J/cm2 to drive the target through two ablation regimes. The occurrence of photomechanical spallation and phase explosion at low and high fluence, respectively, is correlated with the evolution of the NP deposits, which are discussed by providing a physical insight in the interplay between fluence-driven ablation regimes of the target, arrangement kinetics of the deposited species (NPs and vapour species) and (crystalline or amorphous) phase of the NPs. This knowledge is key for controlling the surface plasmon resonance response of AuNPs depending on the designed application.

The ablation of a metal target at laser energy densities in the range of 1–10 TW/cm2 leads to the generation of nanoparticles (NP) of the ablated material. This aspect is of particular interest if the immobilization of NPs on three-dimensional (3D) substrates is necessary as for example in sensing applications. In this work the deposition of Au NP by irradiation of a Au bulk target with a sub-picosecond laser beam (500 fs; 248 nm; 10 Hz) on 2D (silica and Si(100)) and 3D substrates (silica nanowire forests) is reported for different number of laser pulses (500, 1000, 1500, 2000, 2500). A uniform coverage of small Au NPs (with a diameter of few nm) on both kinds of substrates has been obtained using a suitable number of laser pulses. The presence of spherical droplets, with a diameter ranging from tens of nm up to few μm was also detected on the substrate surface and their presence can be explained by the weak electron-phonon coupling of Au. The optical characterization of the samples on 2D and 3D substrates evidenced the surface plasmon resonance peak characteristic of the Au NPs although further improvements of the size-distribution are necessary for future applications in sensing devices.

Since the global energy demand increases annually, a great need is arising in energy-related technologies. Photocatalysis plays a major role in these technologies, as it exploits one of the renewable types of energy, solar energy. For this reason, there is a plethora of scientific investigations in the research field of photocatalysis. In particular, the variety of materials that could be employed to efficiently enhance the procedure, is extensively studied. One of the most widely used materials is titania (TiO 2 ) due to its efficiency in photocatalysis [1] , while maintaining and other notable properties such as non-toxicity, chemo-stability, enhanced electronic and optical characteristics.