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Physical analyses by Laser Ablation coupled to Mass Quadrupole Spectrometry (LAMQS), and Energy Dispersive X-ray fluorescence (EDX) induced by electron beam are applied to the investigation of two silver Tetradrachm Greek coins. Quantitative analysis of elements, silver compounds and isotopic ratios have been investigated in the two samples. Significant differences in the elemental content and in the morphological aspects are observed.

Amorphous CNx thin films were deposited at room temperature by pulsed laser ablation of graphite targets in a controlled atmosphere using both N-2 and N-2/Ar gas mixtures. The structural and electronic properties of the samples were investigated by means of X-ray photoelectron, reflection electron energy loss and Raman spectroscopy. Nitrogen contents as high as 32% have been estimated. The overall results show a progressive transformation of the C-C sp(3) bonds into sp(2) hybridized C-N ones with the development of SP2 carbon clusters upon increasing the gas pressure values. By means of fast photography measurements, different regimes of the laser-induced plasma expansion dynamics have been evidenced. The results indicate that the electronic and structural properties of the laser ablation-deposited CNx films depend strongly on the regime under which the plasma expansion takes place, not simply on the overall nitrogen content. In this respect the role played by the gas composition and pressure are of fundamental importance.

The results of an electron spectroscopy study carried out on a set of pulsed laser deposited CN films are reported. A progressive degree of graphitization, deduced from the continuous increase in the sp 2 bond fraction, has been found for x values up to 25%. The mass density values, deduced by a proper treating of both the x-ray photoelectron spectroscopy and reflection electron energy loss spectroscopy data, are consistent with a material made up by two phases, namely a sp2 threefold (graphite-like) and a sp3 fourfold (diamond-like) coordinated one. The behaviour of the density of the samples as a function of the N content does not show any abrupt change in going from lower to higher nitrogen concentrations as found by other authors, this certainly being due to differences in the starting sp3/sp2 ratio of the films at zero N concentration and to their different preparation parameters.

The electronic and structural properties of amorphous carbon films have been studied by means of Raman and X-ray photoelectron spectroscopy. The films were deposited, under vacuum, by KrF excimer laser ablation of graphite targets. Both the substrate temperature and laser fluence were increased up to 900 K and 15 J cm-2, respectively. The Raman spectra of the films deposited at room temperature showed the presence of a broad band peaked at nearly 1550 cm-1 with a shoulder in the 1300-1400 cm-1 region, with an sp3 content ranging from 60 to 70%. Upon varying the laser fluence, only slight modifications in the Raman spectra were observed. On the contrary, increasing the substrate temperature increased the low-frequency component, suggesting an increase in the sp2 content. This result is also supported by the lineshape modifications observed for the C 1s photoemission peak and by a possible reduction in the film density.