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A fragment of the silver reliquary bust of St. Leo, made in Messina, Italy, in the last of 1739 and now preserved in the church of SS. Savior of Africo Nuovo, Reggio Calabria, Italy, was investigated with spectroscopic techniques (scanning electron microscopy (SEM)+energy-dispersive X-ray (EDX), X-ray diffraction (XRD)) in order to analyze the composition of the sample in terms of elements and compounds. EDX analysis employs an electron beam that interacts with the sample, leading to the emission of characteristic X-rays as secondary radiation. In the XRD analysis, a Cu Kα X-ray radiation is detected by a Si(Li) solid-state detector after the interaction with the sample. The chemical composition of the bulk allowed to identify the constituting metal alloy, while the detection of surface elements and compounds, closely related to the sample preservation, was useful in order to suggest to restorators the best interventions to minimize the conservation problems that could affect the durability of the precious artefact. [ABSTRACT FROM AUTHOR]

Pulsed laser deposition (PLD) and chemical vapour deposition (CVD) have been proven to be among the most successful techniques for growing the entire spectrum of carbon films, which can be used in a wide range of technical applications. Here an investigation has been performed to explore the effect of different growing techniques (PLD and CVD) and process parameters (such as deposition time and substrate type) on the films' morphology and mechanical properties. The mechanical properties of the grown thin films were characterised by means of nano/micro indentation and scratch test techniques. It was observed that the thickness of the Al2O3 interlayer (between the Fe catalyst nanoparticles and the silicon substrate) is a critical parameter that can be used to significantly enhance the adhesion strength of PLD-grown carbon films. PLD-grown carbon films were in fact found to have higher adhesion to the substrate than CVD-grown carbon nanotubes (CNT), and the adhesion strength was found to increase with increasing thickness of the Al2O3 interlayer. On the other hand, CVD-grown carbon films (made of aligned CNTs) seem to offer a greater response in terms of elastic modulus. A thorough scanning electron microscopy characterisation suggested that the observed mechanical responses might be correlated to the films' morphology at the nano/microscale. It was in fact observed that, in PLD-grown samples, an increasing deposition time and Al2O3 content leads to a grain size increase and to a clustering effect, thus to a loss in film uniformity. [ABSTRACT FROM AUTHOR]

Abstract: A study of laser ablation of different targets (Al, Ti, Mo, Au and polyethylene), in vacuum, by using 3ns Nd:YAG laser radiation, at 1064nm wavelength, is reported. The ion emission from the plasma was monitored through time-of-flight (TOF) measurements, performed by using an ion collector placed along the normal to the target surface. The deconvolution of the IC experimental spectra with a Coulomb–Boltzmann-shifted function permitted to evaluate the equivalent ion temperature and the acceleration voltage developed inside the non-equilibrium plasma. The UV plasma emission, detected with an optical spectroscope, permitted to estimate the electronic temperature and density, to evaluate the Debye length and the temperature gradient in the laser-generated plasma plume. [Copyright &y& Elsevier]

A pulsed Nd:Yag laser, at intensities of the order of 1010 W/cm2, is employed to irradiate different thick metallic targets (Ti, Fe, Ag, and Ni) placed in vacuum. The obtained non-equilibrium plasmas are investigated with various analytical techniques. An electrostatic ion energy analyzer and different ion collectors are employed to monitor in situ the ions ejected from the plasma and to determine the core plasma temperature, the ion energy distributions and the ion angular emission. An optical spectrometer is employed to analyze the plasma corona emitted light vs. wavelength and to identify the emitted characteristic lines. The optical spectroscopy permitted to evaluate the electron temperatures and densities. Results show strong temperature and density gradients occurring in the laser-generated plasma plume. [ABSTRACT FROM AUTHOR]

Abstract: A Nd:Yag laser is employed to irradiate thick Fe targets placed in vacuum. The obtained non-equilibrium Fe-plasma is investigated with various analytical techniques. An electrostatic ion energy analyzer (IEA) and a ring ion collector (ICR) are employed, in time-of-flight configuration, to monitor in situ the ejected ions from the plasma along the normal direction to the target surface and to determine the plasma core temperature and the ion energy distributions. The visible plasma emission, detected with an optical spectrometer, permitted to evaluate the electronic temperature and density and the fluence threshold of the visible light emission. The spectroscopy measurements of ions and photons and the fast CCD plasma images are employed to evaluate the temperature gradients in the laser-generated plasma plume. [Copyright &y& Elsevier]

Abstract: Deconvolution of time-of-flight ion currents recorded with an ion collector and cylindrical ion analyser spectra were applied to characterization of production of Au q+ ions (1⩽ q ⩽52) by focusing laser-beam intensity of 5×1014 W/cm2 onto a bulk target. The deconvolution of TOF spectra indicates up to eight current peaks carried by ion groups having different mean ionisation state and different energy. The nature of the laser-produced ion groups depends on the laser pulse characteristics, the focusing conditions and on the non-linear phenomena induced by the interaction of the focused laser pulse with the plasma. Comparison of recovered ion current peaks of multiplies charged Au q+ ions (1⩽ q ⩽9) produced with laser intensity of 3×1010 W/cm2 with reconstructed currents of single charge-states is presented. The multi-peak structure of the current of a single charge-state I q (t) is discussed with regard to charge recombination. [Copyright &y& Elsevier]