This study was carried out on a crucifix located inside the church of St. Mary Major in Acri. The story of this crucifix is not very clear, and its dating is still uncertain, as well; however, it ranges between the 15th and the 14th century. The wooden sculpture of the crucified body of Jesus was painted and the conservation state of the color appeared good. A detailed analysis of the pigments was considered very useful in verifying the restoration history of this crucifix, and to discriminate between the original painting and later restoration activities. A micro-Raman analysis reveals the presence of the classical pigments expected for the estimated age of the crucifix, such as gypsum, terra di Siena, vermilion, carbon black, and others. In addition, other pigments of more recent use were found, such as Prussian blue, titanium white, lithopone, and chromium yellow, mostly in the thong around body of Jesus, which appears green. This is a clear indication of a relevant modification of the artifact in modern times, when the thong was totally painted again; smaller modifications were surely revealed by the presence of “modern” pigments on other points of the body.

Despite intensive investigations in the UV (ultraviolet) and visible range, the research on the optical properties of graphene in the extended near and mid infrared range by means of Spectroscopic Ellipsometry (SE) remains limited yet. Herein, the optical properties of a Chemical Vapor Deposition (CVD)-grown monolayer graphene, transferred from a copper substrate onto SiO2/Si, were studied in the broad energy range (0.38-6.2 eV) using Variable Angle Spectroscopic Ellipsometry (VASE). The morphological and the structural properties of the samples were investigated by Micro-Raman Spectroscopy, Wavelength Dispersive X-ray (WDX) analysis, Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). The Lorentz oscillator model proposed for the optical response of graphene fits very well the experimental data. An unintentional doping, revealed by Micro-Raman Spectroscopy and WDX, is reported.

In this study, a silver/graphene oxide/gold sandwich structure was explored, in which the graphene oxide film is inserted between magnetron sputtered gold and silver thin films. Under laser excitation at low intensity, enhancement effects occur in the so-called ‘hot-spots’, (i.e. spatially localized surface plasmon resonances where the electric field of the laser may generate huge local enhancements of Raman scattering). This aspect was not reported in previous works on sandwich-structured composites, and such results contribute to improving the understanding of GO interaction with magnetron sputtered metal thin films. Micro-Raman technique, Scanning Electron Microscope characterization, Energy-dispersive x-ray spectroscopy analysis and Variable Angle Spectroscopic Ellipsometry were performed. The hot spots activity is associated to the presence of silver nanoparticles, of diameters 40/50 nm, as revealed by Scanning Electron Microscope characterization. Moreover, the distribution of Ag, GO and Au was proved by Energy-dispersive x-ray spectroscopy analysis.

Many cell membranes of living organisms can be represented as phospholipid bilayers immersed into a water environment. The physical-chemical interactions at the membranes/water interface are responsible for the stabilization of the membranes. In addition, the drug efficiency, the pharmaceutical mechanism and the improvement of the drug design can be addressed to the interactions between the membranes-water interface with the drug and to the membrane-drug interface. In this framework, it is important to find membranes models able to simulate and simultaneously simplify the biological systems to better understand both physical and chemical interactions at the interface level. Dimyristoyl phosphatidyl choline (DMPC) is a synthetic phospholipid used in order to make Multilamellar Vesicle (MLV), Large Unilamellar Vesicle (LUV) and Giant Unilamellar Vesicle (GUV). In order to understand the mechanisms of vesicle formation, we have analyzed mixtures of DMPC and water by micro-Raman spectroscopy at different temperatures in the range between 10 and 35 degrees C. Particularly, we analyzed the temperature dependence of the CN vibrational frequency, which appears well correlated to the order degree of the various phases. These investigations, beyond the determination of phospholipid hydrocarbon chains order, provide information about the conformation of the lipid membranes. We have identified the mixture of DMPC/water that is best suited for Raman studies and can be used as an in-vitro model for biological systems. A peculiar frequency shift across the transition gel-ripple-liquid crystalline phases has been proposed as a useful diagnostic marker to detect the "order degree" and subsequently the phases of biomimetic membranes made by DMPC.

The presence of silicon nanocrystals on the surface of standard wafer samples of Si, conserved under “usual” laboratory conditions, has been investigated by micro-Raman analysis, performed for increasing intensity of laser irradiation. The poor thermal connection of such small crystals to the Si wafer bulk allows for the appearance of two well distinct Raman bands in the spectra, with a different evolution for increasing irradiance levels: the first, expected, due to bulk silicon response, the other one assignable to the silicon nanocrystals. A careful analysis of peak position and linewidth has been carried out, both for the Raman contribution from the nanocrystals, reaching high temperatures under irradiation (up to 1400 K), and for the one from the “bulk” Si, which remains practically at room temperature. The analysis of the spectra and the comparison with previous studies on nc-Si suggest that such nanocrystals do not have a very small size, so that the observed changes of spectral parameters are mainly due to laser heating, rather than quantum confinement effects. In any case, we performed also an independent size deter-mination by AFM mapping, confirming a size distribution well peaked be-tween 50 and 100 nm. As a corollary from this analysis, we get the indication that apparent linewidths and positions, at low laser irradiation levels, can be slightly changed in the presence of nc-Si on the surface. It is due to the differ-ent thermal responses of bulk and nanocrystalline components, inducing un-resolved separate components; this hypothesis suggests reanalysing some previous experimental data, in particular for many Raman spectra of Si col-lected at “room temperature”.

In the aim to get high quality graphene films, with large domains and free from impurities, minimizing also the manufacturing costs, we investigate the graphene grown on copper (Cu) foil by chemical vapor deposition at ambient pressure conditions, by using methane (CH4) as carbon source, diluted in a suitable mixture of argon (Ar) and hydrogen (H-2). Several graphene samples were synthesized, for variable exposure times to hydrocarbon precursor, in the range from 1min to 1hr. The quality of the graphene films and their structural, morphological, and electronic properties were evaluated by micro-Raman spectroscopy and other techniques, including, scanning tunneling microscopy, atomic force microscopy, and scanning electronic microscopy. In particular, samples obtained with shorter growth time (less than 10min) exhibit a non-uniform coverage of the Cu surface, whereas those synthesized with exposure time between 10 and 30min show a prevalence of well-ordered monolayer graphene domains. For longer deposition, the amount of disordered domains increases, as revealed by Raman analysis, and the resulting film shows a nonself-limiting growth behavior for chemical vapor deposition at atmospheric conditions. In addition, we observed 2 kinds of monolayer graphene, in terms of coupling with the Cu surface, for the samples synthesized between 10 and 30min. To the best of our knowledge, coupled and decoupled graphene regions have never been reported at the same time on Cu surface. Furthermore, a Raman statistical analysis has been performed on the G and 2D bands measured in both the kinds of regions, gaining evidence of a bimodal behavior for the graphene spots, corresponding to coupled and decoupled configurations. This difference, which is appreciable also by the optical microscopy inspection, could be related to the local Cu oxidation and to oxygen intercalation after graphene growth.

The growth of graphene on copper foil has been performed, following the well-known low-pressure chemical vapor (LP-CVD) procedure. The as-deposited monolayer graphene clearly exhibits two different coupling behaviors with the metal substrate, as demonstrated by visual microscopic investigation and by other experimental techniques, like Scanning Electron Microscopy (SEM) and micro-Raman spectroscopy. The single graphene sheet shows both large areas where it is coupled to the metal substrate and others where it exhibits freestanding-like characteristics. This phenomenology appears to be related to oxidation of the copper surface. In addition, we demonstrate the possibility to induce a variation of the coupling state by visible-light irradiation above a proper power threshold. The resulting change of the coupling with the metal substrate is associated to a local variation of the work function. Applications in high-performance electronic devices can be suitably tailored by optical methods and, in principle, by any local probe producing "hot spots" such as Scanning Tunneling Microscopy (STM) tips and electron beams.

We present a study of adsorption of Cresyl Violet (CV) in aqueous solution on sonicated Graphite Oxide (sGO). For comparison, we also show adsorption results of Methylene Blue (MB) and Acridine Orange (AO) performed in the same conditions. The adsorbent was synthesized by the Tour's method followed by washing in water and ethanol and sonication, without any reduction, and studied by Raman, IR, UV-Vis, SEM and TEM techniques. Our results show that adsorption fits the pseudosecond order model for the three dyes, and that the adsorption quantity for CV is 125.0 mg g(-1), while for MB and AO is 123.3 and 94.6 mg g(-1) respectively.

In the last years the potential of combining the attractive materials characteristics of graphene related materials and silver nanostructures for SERS and metamaterials has emerged. Here, we report of graphene oxide thin films deposited by dip-coating on magnetron sputtered silver thin films. Our work represents a novelty in the field of the study of graphene oxide-silver composites, since magnetron sputtering deposition is an alternative way to silver thin films fabrication; previous works used instead silver nitrate aqueous solution mixed with the graphene oxide. Micro-Raman technique, morphological analysis and variable angle spectroscopic ellipsometry were performed. The final SERS signal intensity was investigated and we found Raman peaks dependent on the intensity of the laser and the thickness of silver and GO films. These results could open somestudies on plasmonics and on the reduction of graphene oxide mediated by silver thin films. Moreover, effective medium theory calculations show the possible use of these graphene oxide/silver thin films in multilayer hyperbolic metamaterials for optical applications. (c) 2017 Elsevier B.V. All rights reserved.

Graphene oxide and reduced graphene oxide thin films are very promising materials because they can be used in optoelectronic devices and in a growing range of applications such as touch screens and flexible displays. In this work, graphene oxide (GO) and thermally reduced graphene oxide (rGO) thin films, deposited on Ti/glass substrates, have been obtained by electrophoretic deposition. The morphological and the structural properties of the samples have been investigated by micro-Raman technique, X-ray reflectometry, and SEM analysis. In order to study the optical and electrical properties, variable angle spectroscopic ellipsometry and impedance analysis have been performed. The thermal annealing changes strongly the structural, electrical, and optical properties, because during the thermal processes some amount of sp3 bonds originally present in GO were removed. In particular, the annealing enhances the Ohmic behavior of the rGO film increasing its conductivity and the estimated optical density. Moreover, using electrophoretic deposition, we have found a higher value of optical density for GO thin films, not observed in GO films obtained with other deposition methods.

Single crystals of Zn-doped enstatite (Mg1−xZnx)SiO3 have been synthesized by slow-cooling flux method using two different fluxes. The starting mixtures were first held at a temperature between 1350 and 950 °C and then slowly cooled to the final temperature (600–750 °C) at four different rates. The grown crystals were characterized by binocular microscope, X-ray powder diffraction, scanning electron microscopy with energy-dispersive spectrometry. When LiCO3, MoO3 and V2O5 were used as flux, Zn-doped enstatite crystals up to 3.5 mm in length grew successfully. They were transparent in color and showed the typical prismatic form. Chemical analyses on several Zn-doped enstatite crystals showed that the amount of Zn2+ indicated as ZnO wt% ranges from 3.37 to 10.49 wt%. Further characterization by cathodoluminescence and by µ-Raman spectroscopy allowed us to study the effect of zinc dopant on the chemical/physical characteristics of the doped enstatite.

The Raman spectra of polyhedral carbon nano-onions (PCO), obtained by underwater arc discharge of graphite electrodes, are studied. While the general Raman spectrum of PCO is very similar to those of other carbon nanostructures, including spherical nano-onions, the fine structure of the G and 2D bands gives valuable information that allows using Raman spectroscopy for differentiating the PCO from other carbon structures. The interpretation of the features of the fine structure of the spectra is supported by evidences obtained by TEM.

In the present work, thirteen samples collected from the Grotta Inferiore di Sant'Angelo near the town of Cassano allo Jonio (Calabria region, southern Italy) were analyzed for their mineralogy. The Grotta Inferiore di Sant'Angelo is made up of sub-horizontal, interlinked galleries between 400 and 450 meters above sea level. The floor is littered with deposits sucli as bat-guano, gypsum, and many speleothems that also cover the walls. The samples were identified and characterized by X-ray powder diffraction, scanning electron microscopy with energy dispersive spectrometer, microthermometry, and micro-Raman spectroscopy. The ten primary minerals identified in this study belong to six different groups: carbonate, sulfate, apatite, oxide and hydroxide, halide, and silicate. Clay minerals and eight other detrital minerals were also found: enstatite, rutile, magnesite, pyrite, chrysotile, quartz, dolomite, and chlorite. Characterization of cave minerals could be useful to improve the knowledge of the relation between them and the lithology of the host rocks.

Supersonic molecular beam deposition is a far-from-thermal-equilibrium kinetic activated growth technique, which allows the fine control of the kinetic energy of molecular species. We present a study of the growth of very thin layers of copper phthalocyanine on nanostructured surfaces of titanium dioxide nanograins; the study combines time-of-flight secondary ion mass spectrometry, Raman, X-ray photoelectron spectroscopy, and multivariate statistical analysis. Different kinetic energies and layer thicknesses were considered to investigate bond formation and surface interaction between the organic molecules and the inorganic nanograins. This study allowed the clarification of the key role of the energetic properties of the supersonic beam in the surface activation, enabling bond formation, not available with other processes at equilibrium. In particular, high kinetic energy regimes for copper phthalocyanine molecules in high-dilution seeded beams allow the formation of stronger bonds at the interface, which is useful for producing innovative nanohybrid materials having specific improved structural and chemical characteristics. The comparison among different surface characterization measurements orchestrated by multivariate statistical analysis proved to be a valuable approach for surface interaction study and interpretation.

Millimetric Mn‐doped enstatite (MgSiO 3 ) crystals have been grown by slow cooling in MoO 3 , V 2 O 5 , and Li 2 CO 3 flux. Six starting mixture with different amount of manganese were slowly cooled from 1350 °C, 1050 °C and 950 °C down to 750 °C, 650 °C and 600 °C respectively. The enstatite crystals were characterized by X‐ray powder diffraction (XRPD) and scanning electron microscopy with energy‐dispersive spectrometry (SEM/EDS). Mn‐doped enstatite crystals were reddish in color, euhedral and elongate parallel to c‐axis. The largest enstatite crystal obtained is 8.5 mm in length. The effects of growth parameters on yield and size of crystals were studied. Variations observed in crystal size were attributed to the amount of Mn doping. Further characterizations by μ‐Raman spectroscopy (μ‐R) and cathodoluminescence (CL) allowed to study the effect of Mn doping on some chemical/physical characteristics of the enstatite and to assess its potential in advanced technological applications.

The electronic, morphological and structural properties of WO3 thin films, synthesized via a sol-gel route and deposited on ITO/glass substrates by spin-coating, were analyzed as a function of annealing temperature (100-700 degrees C range) by Scanning Electron Microscopy, Atomic Force Microscopy, microRaman spectroscopy, X-ray Diffraction and Photoelectron Spectroscopy. We have found evidence of two competing processes when the film is annealed at high temperatures (600-700 degrees C): a structural phase transition from amorphous to crystalline WO3 and a temperature-activated diffusion of sodium ions, from the substrate into the WO3 film, which induces the formation of sodium tungstate. The surface of the films was found to be oxygen deficient after deposition but reverted to fully oxidized WO3 after high temperature annealing in air. The annealing also induced a restructuring of the films with formation of nano-crystalline aggregates. The influence of film thickness on these processes was also investigated. (C) 2014 Elsevier B.V. All rights reserved.

This work reports the peculiar properties of a graphene film prepared by the chemical vapor deposition of ethylene in high vacuum on a well oriented and carefully cleaned Pt(111) crystal surface maintained at high temperature. In‐situ and ex‐situ characterization techniques (low‐energy electron diffraction, high‐resolution electron energy loss spectroscopy, scanning electron microscopy and Raman micro‐spectroscopy) used here indicate the prevalence of single‐layer regions and the presence of two different orientations of the graphene sheets with respect to the Pt(111) substrate. In most of the deposited area, evidence is found of a compressive stress for the graphene lattice, as a net result of the growth process on a metal substrate. This graphene film grown on Pt(111) exhibits a lower degree of order and of homogeneity with respect to the exfoliated graphene on Si/SiO 2 , as it is found generally for graphene on metals, but several characterization techniques indicate a better quality than in previous deposition experiments on the same metal substrate. Copyright © 2013 John Wiley & Sons, Ltd.

Vanadium pentoxide, V2O5, is one of the most widely studied electrode materials. A promising way to improve its conduction properties is to grow V2O5 gels confined in nanoporous structures. In this work Al2O3 filtration membranes with 200nm pores were used as template for the growth of nanopore-confined V2O5·nH2O xerogels. Impedance spectroscopy was performed in the range from 1Hz to 40MHz to study their conductivity and micro-Raman spectroscopy was also performed to investigate their structural evolution. Two kinds of proton conduction could be observed: one for water confined in the bulk crystal lattice and a second one associated with water intercalated in the ribbon-like structures associated with V2O5 xerogels. Both types of conduction were found to be increased in xerogels confined in nanopores. This increase in proton conduction was attributed to better orientation of V2O5 in the pores and to the more amorphous nature of the confined xerogel.

The vibrational properties of yttrium orthovanadate (YVO4) single crystals, with tetragonal zircon structure, have been investigated by means of polarized micro-Raman spectroscopy and ab initio calculations. Raman spectra were taken at different polarizations and orientations carefully set by the use of a micromanipulator, so that all of the twelve Raman-active modes, expected on the basis of the group theory, were selected in turn and definitively assigned in wave number and symmetry. In particular the E-g(4) mode, assigned incorrectly in previous literature, has been observed at 387 cm(-1). Moreover, the very weak E-g(1) mode, peaked at about 137 cm(-1), was clearly observed only under some excitation wavelengths, and its peculiar Raman excitation profile was measured within a wide region of the visible. Finally, ab initio calculations based on density-functional theory have been performed in order to determine both Raman and infrared vibrational modes and to corroborate the experimental results. The rather good agreement between computational and experimental frequencies is slightly better than in previous computational works and supports our experimental symmetry assignments. DOI: 10.1103/PhysRevB.86.214305

This work presents an improved platform for single-site electroporation and controlled transfectants delivery. The device consists of a gold microelectrode array (MEA) with integrated microfluidics and nanostructured titanium dioxide (ns-TiO2) functionalized electrodes for the improvement of cell adhesion. Human cervical cancer cells (HeLa) have been successfully cultivated on chip surface using traditional protocols. The system has been previously tested by electroporating HeLa cells with Lucifer Yellow (LY) and then, in order to validate the approach and cell viability, with plasmid for the enhanced expression of Green Fluorescence Protein (pEGFP-N1) delivered through microchannels.