In this work, we illustrated a method for controlled growth of ZnSe/ZnS core/shell semiconductor and their insertion in a TiO2 anatase bulk. Core/shell quantum dots were grown by Laser Ablation in Solution followed by heating and sonication phases. Shape and dimensions of nanoparticles were controlled by measurements of optical absorption during laser irradiation. The obtained quantum dots, with a ZnS core and a ZnSe shell and radius dimensions of about 12nm, were spray-dried in film of anatase grains and characterized as photoanode for application on Graetzel cells. The efficiency of our hybrid photoanode is about 25% higher than classic organic dye/anatase.

In this paper, we introduce the use of the atomic force microscope (AFM) and of the pulsed laser ablation as methods for morphological diagnostic with nanoscale precision of archeological artifacts and corrosive patina removal from stone artifacts. We test our methodology on stone artifacts extracted from the Church of Sotterra (located in Calabria, South Italy). The AFM microscopy was compared with different petrographic, chemical, optical and morphological analysis methods for identifying the textural characteristics, evaluating the state of preservation and formulating some hypotheses about the provenance and composition of the impurity patina located on the artifact surfaces. We demonstrate that with the nanometric precision obtained with AFM microscopy, it is possible to distinguish the different states of preservation, much better than using conventional petrographic methods. The surface’s roughness is evaluated from very small artifact’s fragments, reducing the coring at micrometric scale with a minimal damage to the artworks. After the diagnosis, we performed restoration tests using the pulsed laser ablation (PLA) method and compared it with the more common micro-sandblasting under dry conditions. We find that the PLA is highly effective for the removal of the surficial patina, with a control of a few hundreds of nanometers in the cleaning of surface, without introducing chemical or morphological damages to the artifacts. Moreover, PLA can be easily implemented in underwater conditions; this has the great advantage that stone and pottery artifacts for marine archeological sites do not need to be removed from the site.

We present a morphology study on laser ablation produced metal nanoparticles (NPs) deposited on carbon nanotube (CNT) substrates. We analyzed the coating geometry and topography by processing AFM and SEM images. Our results show that Ag NPs aggregate together to form large agglomerates, that Ti NPs are well dispersed on the substrate surface forming a quasi-continuous layer, and that Co, Ni, and Al NPs coat quite uniformly CNTs and locally grow in a layer like fashion. We interpret the coating and clustering geometries in terms of cohesion, surface, and interfacial energies and diffusion barriers. Fractal analysis of composites morphology suggests the formation of structures with a smoother topography relative to pure carbon nanotubes for reactive metal nanoparticles.

In this work, we propose using the pulsed laser ablation technique in solution as a ‘chemical-free’ method for forming biatomic or multiatomic semiconductor quantum dots. In particular, we present the results of the formation and characterization of ZnS nanoparticles by laser ablation in solution as a case study for all semiconductors of the III and IV groups. We obtain results comparable to those obtained by chemical methods without the use of surfactants and without changing the crystallinity of the precursor target. Colloidal solutions of nanoparticles with different dimensions were obtained by varying the irradiation time during laser ablation. A study of the morphology and changes in the band edge indicates the formation of ZnS quantum dots with dimensions <4 nm for an irradiation time of less than 10 s. The changes in the band edge were studied in terms of the effective mass approximation model, which indicates, for low irradiation times, the formation of quantum dots with radii ranging from 2.5–2.8 nm and band edges ranging from 4.21–4.15 eV. Raman measurements indicate that quantum dots have the same crystallinity as bulk grains, while photoluminescence measurements clearly show a rearrangement of Zn and S atoms, eliminating the vacancies defects of the bulk material.

We present an experimental study adsorption of molecular gases (N2, H2, O2, CH4, C2H4, and C2H6) on multiwalled carbon nanotubes (MWCNTs) and MWCNT doped with Ag at low temperatures (35 K) and pressures (10−6 Torr) using the temperature programmed desorption technique. Our results show that the desorption kinetics is of the first order; furthermore comparative measurements indicate that Ag/MWCNTs have an adsorption capacity higher than that of a pure sample suggesting that these composites are good candidates as gas cryosorbers for applications in cryopumps or sensor of latest generation.

In this work we present the results of a study of growth and characterization of metal nanoparticles (Ag, Au, and Co)/carbon surfaces. The nanoparticles grew by laser ablation technique and their dimensions were controlled by light scattering study and AFM microscopy before their insertion on graphite surface. Nanoparticles appear randomly disposed on carbon surfaces aggregating to form big particles only in the case of silver. The different behavior of metal nanoparticles on carbon surface was explained in terms of different metal wetting of surface, in agreement with previous theoretical results of He et al. Chemical information, obtained by X-ray photoelectron spectroscopy, indicated that the doping process is a simple physisorption while the interfacial interaction between particles and carbon layers causes local defects in graphite structure and the appearance of a strong photoluminescence signal for all composites. Moreover, the visible optical absorption decreases about 10% indicating the progressive metallization of carbon surface.

The optical and chemical properties of Ag/TiO2 nanocomposites were investigated to explore the possibilities of incorporating these new materials in Gratzel photoelectrochemical cells. The nanocomposites were obtained doping TiO2, in both allotropic species anatase and rutile, with silver nanoparticles (grown by laser ablation process). X-ray photoelectron data indicate the absence of Ag-Ti chemical bonds, while measurements of photoluminescence and optical absorbance in UV-visible range show a quench in photoluminescence emission of about 50% and an increase in visible absorbance of about 20%. Measurements of optical band gap, obtained by Tauc’s equation, indicate a variation of about 1.6 eV.

In this work we present a study of laser ablation (LA) restoration techniques and of thermoluminescence dating process (TL). The main aim of the work is to demonstrate that LA don’t affect the possibility to date ceramic artifacts after restoration. We ablate Neolithic ceramics in air with a first harmonic of laser YAG (1064 nm) and dating the artifacts before and after the cleanness process. We obtain a discrepancy of 200 years (3300 B.C. and 3100 B.C. before and after cleanness respectively), value which is in below limits of experimental error. Moreover, we monitor the temperature of artifacts during the LA at the point of sampling for dating. We observe that the maximum temperature reached is about 100?C, not enough to empty the metastable traps that cause the luminescence signal.

In this work, we introduce a new method for the consolidation of ceramic artifacts using SiO2 and TiO2 nanoparticles (NPs). We study the influence of NPs in the restoration process based on luminescence diagnostics and dating techniques. The nanoparticles were grown by laser ablation in solution and their shape and dimensions were monitored by optical absorption and AFM morphology studies. The colloidal solutions are mainly made of spherical nanoparticles with dimensions of about 10 and 15nm following a LogNorm distribution with a standard deviation less than 1nm. The colloidal solution was then deposed on pottery surfaces to obtain a transparent film with thickness of about 1μm. All chemical and morphological analysis indicate that the NPs consolidate the artifact penetrating in the deeper surface layer and forming a transparent and hydrophobic film on the surface. The adsorption process is a typical physisorption mechanism without formation of chemical bonds between the NPs and the constitutive elements of ceramic and without introduction of external impurities, which can damage the materials. Finally, our results indicate a strong influence of NPs on the luminescence emission by the artifacts and then in the thermoluminescence dating process for restored ceramics.

The aim of this work is the characterization, with different diagnostic tests, of three fragments of bronze artefacts recovered from the Villa of the Quintilii (located in the south of Rome). In particular, the sample alloys were investigated by different chemical and morphological analysis. Firstly, an analysis of the alloy, implemented through the electronic spectroscopy, was taken to discriminate the bronze morphology and its elemental composition. Subsequently, a surface analysis was realized by molecular spectroscopy to identify the alteration patinas on surfaces (such as bronze disease). Two diagnostic techniques are used for the alloy analysis: scanning electron microscopy (SEM) connected to the EDX spectroscopy (to study the morphology and alloy composition) and Auger electron spectroscopy (AES) (to identify the oxidation state of each element). Moreover, for the study of surface patinas, IR and Raman spectroscopies were implemented. All studies were performed on the “as received” samples, covered by a thin layer of excavated soil and on samples processed in an aqueous solution of sulphuric acid (10%), to remove patinas and alterations.

In this work, we present a study of growth and characterization of nanocomposites, based on multiwalled carbon nanotubes and metal nanoparticles (Al, Ag, Au, Co, Cu, Fe, Ni and Ti).We observe a very different behavior between noble and transitions metals.All the nanocomposites are characterized by a network of carbon nanotubes with randomly insertion of spherical metal particles with dimensions of about 100 nm (clearly visible in SEM images).In particular, in transition metal nanocomposites, each tube on sheet surface is covered by particles of about 40 -50 nm and for all metals the XPS measurements indicate the absence of chemical bonds and the simply physisorption of nanoparticle on carbon nanotube buckypaper.Furthermore, the nanocomposites show very different properties respect to pure carbon nanotubes: they are hydrophobic, their roughness is about 50% smaller than carbon nanotube and they exhibit a strong visible photoluminescence, which is absent in pure nanotube.

In this work we present a method for preparing carbon nanotubes/titanium dioxide (CNTs/TiO2) composites with a simple metal vaporization technique in ultra high vacuum ambient at high temperature. We obtain a composite with a highly uniform layer of Ti/TiO2 on CNT and measure exactly the ratio between composites with X-ray Photoemission Spectroscopy (XPS). The obtained Ti-TiO2 film has a thickness of about 1.5 micron and it is perfectly super imposed to carbon nanotubes buckypaper without formation of chemical bonds between tubes and Ti at interface. Comparison between TEM images taken from CNT before and after the treatment indicates the absence of deformation and changes in tube structures. The crystallinity of deposed TiO2 was investigated by Fourier Transform Infrared Spectroscopy (FTIR) which indicate the only presence of anatase. Titanium dioxide is produced by bonds between evaporated Ti atoms and oxygen already adsorbed on carbon nanotubes. Moreover the produced film is very stable and we do not observe changes in Ti percentage after several annealing cycles at high temperatures (500 degrees C).Finally cathode-luminescence measurements indicate the formation of TiO2 film without presence of oxygen vacancies defects. (C) 2012 Elsevier B.V. All rights reserved.

In this work we present two new methods to obtain TiO 2 transparent coverage and to impart superhydrophobicity to stones and ceramics surface of monuments.The first method, adapted for small artifacts easily transportable in restoration laboratory, consists of a simple evaporation of Ti directly on ceramic surface in a controlled oxygen atmosphere.The second method consents the coverage of large surface directly in situ.The TiO 2 is evaporated on a salt surface with desired dimensions and then deposited on ceramic surfaces.In both cases the dioxide layers are transparent, don't damage the ceramic surfaces and are easily removable.In fact, the dioxide layer can be removed simply by 30 minutes of laser ablation process.

Chua's oscillator is a dynamical system by which it is possible to investigate chaos both from the theoretical and the experimental point of view. Studying this system, many strange attractors have been observed and many routes to chaos have been discovered. Furthermore generalizations of Chua's oscillator have been found which present n-scroll attractors. In this paper we propose a methodology for reading the complexity of such systems. We have analyzed the bifurcation map of a system with a 4-scroll attractor and we have been able to perform sound analysis and synthesis of its solutions and to construct 3D images and musical pieces which follow the relevant changes in the behavior of this dynamical system.