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Deuterium-Deuterium fusion processes were generated by focusing the 3 TW PALS Laser on solid deuterated polyethylene targets placed in vacuum. Deuterium ion acceleration of the order of 4 MeV was obtained using laser irradiance Iλ2 ∼ 5 × 1016 W μm2/cm2 on the target. Thin and thick targets, at low and high density, were irradiated and plasma properties were monitored “on line” and “off line”. The ion emission from plasma was monitored with Thomson Parabola Spectrometer, track detectors and ion collectors. Fast semiconductor detectors based on SiC and fast plastic scintillators, both employed in time-of-flight configuration, have permitted to detect the characteristic 3.0 MeV protons and 2.45 MeV neutrons emission from the nuclear fusion reactions. From massive absorbent targets we have evaluated the neutron flux by varying from negligible values up to about 5 × 107 neutrons per laser shot in the case of foams targets, indicating a reaction rate of the order of 108 fusion events per laser shot using “advanced targets”.

The maximum ion energy and acceleration efficiency have to be increased for practical applications of intense ion beams produced by intense short laser pulses incident on a thin foil. For this aim, we propose to use foil with a microscopic structure on the front size. We have prepared such targets by depositing a monolayer of polystyrene nanospheres of a size comparable to laser wavelength on a thin foil. The damage threshold of the produced targets is found experimentally above 3.5 × 109 W/cm2 for a nanosecond pedestal and above 1011 W/cm2 for femtosecond prepulses.

A Pulsed ns laser operating at 532 nm wavelength with 150 mJ pulse energy was employed to irradiate micrometric thick mylar films, from 1 to 100 μm thick, covered by 0.05 μm Au in the back face. Protons and light ions have been accelerated by the electric field developed in the non‐equilibrium plasma by the laser pulse in a vacuum at an intensity of the order of 1010 W/cm2. Time‐of‐flight technique, obtained using a Faraday cup and a fast storage oscilloscope, is employed to measure the ion velocity, energy, and yield emitted in backward and forward directions. The yield of the emitted plasma photons is also evaluated. Two ion collectors are used in opposite directions to measure the plasma radiations emitted in backward and forward directions. Data analysis is based on the Coulomb‐Boltzmann‐shifted (CBS) distribution function. The target ablation yield is evaluated in the order of 3.5 μm per laser shot. [ABSTRACT FROM AUTHOR]

The time-dependent graphene oxide (GO) reduction in medium vacuum under ultraviolet (UV) irradiation at 365 nm has been investigated. We found that GO exposed to UV at room temperature and at a vacuum of about 10−1 mbar shows a notable oxidation for irradiation times up to about 60 min followed by a successive reduction up to 210 min. Characterization measurements have been performed mainly using the Attenuated Total Reflectance (ATR) Fourier Transform Infrared (FTIR) and Raman spectroscopies. ATR-FTIR spectra, acquired in the (400–4000) cm−1 wavenumber range, have indicated an initial decrement of the IR transmission (oxidation process) with the exposure time up to about 60 min and a successive increase of the IR transmission (reduction process) for greater irradiation times up to 210 min. The IR transmission bands are attributed to the oxygen functional groups contained in GO which increase for low UV exposure times and gradually disappear during the UV-induced reduction process. Raman spectra confirm this interpretation showing a decrease of the AD/AG ratio value, with respect to the GO virgin value, for low UV exposure times and an increase for greater times. The GO oxidation and reduction processes, due to the UV GO treatment in medium vacuum conditions, have been also verified by energy dispersive X-ray fluorescence and surface wettability measurements. [ABSTRACT FROM AUTHOR]

A silicon carbide (SiC) plasma has been produced by a Q-switched laser at 1064 nm, 3 ns pulse and 1010 W/cm2 intensity, in high vacuum to investigate the fundamental mechanisms of laser-semiconductor interaction. Although the high hardness and chemical stability restrain the SiC micromachining, it is a valuable semiconductor for devices working under extreme conditions.The plasma has been characterized by using time-of-flight (TOF) measurements of ions detected by an ion collector ring (ICR) and an ion energy analyzer (IEA). Fast CCD camera, quadrupole mass spectroscopy (QMS) and surface profiler have been employed to provide deep insights into the laser-SiC interaction mechanisms.Ion kinetic energies, charge states, plasma expansion velocity, ablation yield per laser pulse, plasma temperature and density have been measured.Applications of the laser-generated plasma are presented and discussed. [ABSTRACT FROM AUTHOR]

Polymethylmethacrylate (PMMA) has been irradiated by 365 nm UV wavelength at different exposition times in air and room temperature. The macromolecular modifications induced in the polymer have been investigated using attenuated total reflectance (ATR) coupled to Fourier transform infrared (FTIR) spectroscopy, UV-Visible spectroscopy, surface profiler, wetting ability, and electronic microscopy. The observed chemical, optical and morphological changes occurred as a consequence of the UV irradiation suggest that chain scissions are induced by the UV radiations, with reduction of the IR and visible transmittance, wetting ability and surface roughness. The study of the degradation of PMMA by different times of exposure to UV radiation is investigated with the aim of understanding the effects produced over time on optical devices such as intraocular lenses, optical fibres, protective screens, and instrumental lenses. [ABSTRACT FROM AUTHOR]

A ns-pulsed laser operating at 532 nm wavelength has been employed to irradiate micrometric mylar films (1–100 μm) with an attached 0.1 μm Al film on its back face. Protons and light ions have been accelerated by the electric field developed in the non-equilibrium plasma generated by the laser pulse in a vacuum at an intensity of the order of 1010 W/cm2. The Time-of-flight (TOF) technique, using a Faraday cup (ion collector) coupled to a fast storage oscilloscope, has been employed to measure the ion velocity, energy and yield. The yield of plasma-emitted photons has been also evaluated. Two ion collectors have been used in opposite directions to measure the maximum ion acceleration by the TOF data acquired in backward and forward directions and the photon yield as a function of the target thickness. The evaluation of the ion energy distribution has been based on the Coulomb-Boltzmann-Shifted (CBS) distribution function. [ABSTRACT FROM AUTHOR]

Graphene nanoplatelets/polydimethylsiloxane (GNPs/PDMS) nanocomposites foils are obtained by dispersing nanoplatelets of graphene (GNPs) into polydimethylsiloxane (PDMS) at a given GNPs concentration but at different curing times to study the effects of curing time on some their bulk and surface properties. Their appearance and morphology have been examined by optical and scanning electron microscopies, their wettability and roughness by the sessile drop method and profilometry, their bonds by µRaman and ATR-FTIR spectroscopies, their dielectric response by dielectric spectroscopy. In particular, optical and SEM images and roughness measurements indicate a roughened and hydrophobic surface at the shortest curing time that becomes less roughened, more uniform and less hydrophobic as curing time increases. ATR-FTIR and µRaman spectra reveal the absence of chemical interaction between GNPs and PDMS. The behavior of the PDMS real and imaginary parts of dielectric permittivity without and with GNPs and at increasing curing times seems to define the obtained GNPs/PDMS nanocomposites as low-loss materials. The obtained results show that the curing time significantly affects the filler distribution in the PDMS matrix and consequently the properties of the final nanocomposites. [ABSTRACT FROM AUTHOR]

The laser irradiation of TiH2 targets has been investigated to measure the proton energy transferred by hot non‐equilibrium plasmas in vacuum. The proton and titanium emission have been monitored by time‐of‐flight measurements to evaluate their maximum ion energy and dependence on the laser intensity. Backward and forward plasma have been generated in the range 1010–1016 W/cm2 intensity using ns and sub‐ns laser shots. Proton energy has been measured by tens eV up to about 4 MeV. The interest in proton beams generated by laser‐plasma is presented and discussed. [ABSTRACT FROM AUTHOR]