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Abstract The electronic and topographical structure of vapour-deposited graphene on copper is known to deteriorate in ambient conditions with time. This appears in X-ray absorption spectra at the carbon 1s edge as a reduction of π*- and σ*-resonance intensities and as fine structures at energies between the resonances. Our Density Functional Theory calculations show that the intensity reduction is due to the wrinkling of the graphene sheet, which may also cause a hitherto unobserved splitting of the σ*-resonance. The structure between the resonances can be due to adventitious adsorbates either at grain boundaries or at the graphene surface. The location of adsorbates, such as carboxyl, can be distinguished through the degree of anisotropy of the absorption. The hydrogen and carboxyl adsorbates at the graphene surface correspond to effectively isotropic peaks in the absorption spectrum, since the receiving carbon atom in the graphene sheet adopts sp 3 hybridisation. In contrast, carboxyl groups at the edges of graphene grains are predicted to only cause the anisotropic absorption of photons. This informs the interpretation of an experimentally observed X-ray absorption peak at 288.3 eV, which often persists even after high-temperature vacuum-annealing of graphene and may be caused by adsorbates clustering at the basal plane. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

The paper presents several types of thermal barrier type ceramic layers and the variations concerningtheir porosity and adherence related with their chemical composition. The structural and compositionalcharacterization of the obtained layers was performed by electron microscopy, one of the most relevantinvestigation methods in order to choose the optimum composition for the external layer deposited on copperdevices. The effect of quick thermal shock on the samples porosity and on chemical elements distribution alongthe layer’s thickness was also taken into account.

Two gilded miniature portraits on copper support from the Evora Museum collection (Portugal) were examined and analysed by stereomicroscopy, μ-Raman spectroscopy, SEM–EDS, portable-XRF (pXRF), μ-FTIR spectroscopy and liquid chromatography coupled to diode array and mass spectrometry detection (LC-DAD-MS). Both portraits, one of a gentleman and the other of a lady, are notable paintings of comparable richness, which present several areas painted or covered with gold (namely, gold dust to compose and highlight different ornaments and gold leaf to cover the back of one of the portraits). The gold dust, the gold leaf and the materials used in the gilding technique were investigated non-invasively and non-destructively using stereomicroscopy, SEM–EDS, pXRF and μ-FTIR. The other materials of the paintings, like the inorganic pigments and extenders, were successfully identified by μ-Raman spectroscopy, while the organic red pigment cochineal lake was positively identified by LC-DAD-MS. Overall, the materials identified in these 17th century paintings are broadly consistent with those mentioned in the painting treatises of that time, or with those reported in a very limited number of material studies focused on artworks of the same kind and period. [ABSTRACT FROM AUTHOR]

Seventeen Portuguese miniature portraits on copper support from the Évora Museum collection (Portugal) were analyzed in situ and nondestructively by Raman microscopy (RM), SEM-EDS, and stereomicroscopy. This work constitutes a great breakthrough in the study of miniature paintings from the 17th and 18th centuries, since the chemical information known about this unique kind of paintings are still scarce, and in particular, this exclusive collection was never been subjected to any physicochemical study. In this work, each portrait was examined in detail in order to characterize the pigments palette used by the miniaturists. The μ-Raman analysis, in particular, guaranteed an exceptional visualization and good individual identification of small grains of pigments and other constituents of the pictorial layer. Using this technique, 19 compounds were identified, including bluish black covellite, a pigment rarely found in oil paintings. SEM-EDS was used as an important complementary technique to confirm the chemical nature of some pigments and to identify shell gold (gold dust) in some portraits. Overall, the pigments identified in this large set of old paintings are broadly consistent with those mentioned in the painting treatises of that time or reported in other more modern bibliographic sources. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The paper presents several types of thermal barrier type ceramic layers and the variations concerning their porosity and adherence related with their chemical composition. The structural and compositional characterization of the obtained layers was performed by electron microscopy, one of the most relevant investigation methods in order to choose the optimum composition for the external layer deposited on copper devices. The effect of quick thermal shock on the samples porosity and on chemical elements distribution along the layer's thickness was also taken into account. [ABSTRACT FROM AUTHOR]