The adsorption of adenine on silver and gold surfaces has been investigated combining density functional theory calculations with surface-enhanced Raman scattering and angle-resolved X-ray photoelectron spectroscopy measurements, obtaining useful insight into the orientation and interaction of the nucleobase with the metal surfaces.

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Chemical compositions of impact melt breccias and target rocks from the Tenoumer impact crater, MauritaniaAbstract-The impact melt breccias from the Tenoumer crater (consisting of a fine-grained intergrowth of plagioclase laths, pyroxene crystals, oxides, and glass) display a wide range of porosity and contain a large amount of target rock clasts. Analyses of major elements in impact melt rocks show lower contents of SiO 2 , Al 2 O 3 , and Na 2 O, and higher contents of MgO, Fe 2 O 3 , and CaO, than the felsic rocks (i.e., granites and gneisses) of the basement. In comparison with the bulk analyses of the impact melt, the glass is strongly enriched in Si-Al, whereas it is depleted both in Mg and Fe; moreover, the impact melt rocks are variably enriched or depleted in some REE with respect to the felsic and mafic bedrock types. Gold is slightly enriched in the impact melt, and Co, Cr, and Ni abundances are possibly due to a contribution from mafic bedrock.Evidences of silicate-carbonate liquid immiscibility, mainly as spherules and globules of calcite within the silicate glass, have been highlighted.HMX mixing calculation confirm that the impact melt rocks are derived from a mixing of at least six different target lithologies outcropping in the area of the crater. A large contribution is derived from granitoids (50%) and mica schist (17-19%), although amphibolites (∼15%), cherty limestones (∼10%), and ultrabasites (∼6%) components are also present.The very low abundances of PGE in the melt rock seem to come mainly from some ultrabasic target rocks; therefore, the contamination from the meteoritic projectile appears to have been negligible.

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Lapis Lazuli is one of the oldest precious stone, being used for glyptic as early as 7000 years ago: jewels, amulets, seals and inlays are examples of objects produced using this material. Only few sources of Lapis Lazuli exist in the world due to the low probability of geological conditions in which it can form, so that the possibility to associate the raw material to man-made objects helps to reconstruct trade routes. Since art objects produced using Lapis Lazuli are valuable, only nondestructive investigations can be carried out to identify the provenance of the raw materials. In the present work a systematic study of the luminescence properties of Lapis Lazuli under charged particles irradiation is reported. In a first phase a multi-technique approach was adopted (CL, SEM with microanalysis, micro-Raman) to characterise luminescent minerals. This characterisation was propaedeutic for IL/PIXE/PIGE measurements carried out on significant areas selected on the basis of results obtained previously. Criteria to identify provenance of Lapis Lazuli from four of the main sources (Afghanistan, Pamir Mountains in Tajikistan, Chile and Siberia) were proposed.

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Abstract-Libyan Desert Glass (LDG) is an enigmatic type of glass that occurs in western Egypt in the Libyan Desert. Fairly convincing evidence exists to show that it formed by impact, although the source crater is currently unknown. Some rare samples present dark-colored streaks with variable amounts of Fe, and they are supposed to contain a meteoritic component. We have studied the iron local environment in an LDG sample by means of Fe K-edge highresolution X-ray absorption near edge structure (XANES) spectroscopy to obtain quantitative data on