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Abstract: We analyze the UV–vis absorption spectra of zinc oxide water colloids, prepared by pulsed laser ablation in liquids (PLAL), through a theoretical approach based on the multipole expansion of the electromagnetic fields and the transition matrix method. We reproduce the optical behaviour of these colloidal solutions also at wavelengths shorter than the one at the absorption edge. We extend our analysis to estimate the particle concentration taking into account the size distribution of the colloidal dispersion of the ZnO spherical nanoparticles. Moreover, we study the pulsed laser irradiation effects on the UV–vis absorption spectra of ZnO nanocolloids. Laser irradiation changes the morphological rearrangement of the ZnO nanoparticles. We are able to discriminate whether the irradiated sample is characterized by nanostructures with large or small aspect ratio. In this way, information about particle size distribution, concentration, and morphology can be obtained without performing any morphological characterization. [Copyright &y& Elsevier]

Abstract: Some Egyptian bronze coins, dated VI–VII sec A.D. are analyzed through different physical techniques in order to compare their composition and morphology and to identify their origin and the type of manufacture. The investigations have been performed by using micro-invasive analysis, such as Laser Ablation and Mass Quadrupole Spectrometry (LAMQS), X-ray Fluorescence (XRF), Laser Induced Breakdown Spectroscopy (LIBS), Electronic (SEM) and Optical Microscopy, Surface Profile Analysis (SPA) and density measurements. Results indicate that the coins have a similar bulk composition but significant differences have been evidenced due to different constituents of the patina, bulk alloy composition, isotopic ratios, density and surface morphology. The results are in agreement with the archaeological expectations, indicating that the coins have been produced in two different Egypt sites: Alexandria and Antinoupolis. A group of fake coins produced in Alexandria in the same historical period is also identified. [Copyright &y& Elsevier]