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Nantokite (CuCl) locked inside subsurface micro-pits has been recognised as the driving force to the form of corrosion called bronze disease. The use of the traditional corrosion inhibitor benzotriazole is questioned because of toxicity. So there is a need for alternative conservation treatments. This work is focused on the experimental design to test the effectiveness of sodium oxalate followed by treatment with limewater to face bronze disease on outdoor bronzes. A number of foundry bronze coupons were exposed to weathering at Genoa Experimental Marine Station (GEMS) exposure site and sprayed twice a week with a 5% NaCl solution for the first 124 days. After 562 days of natural weathering, the patinas on coupons were characterised with non-destructive techniques (NDT) and the presence of nantokite was verified. We designed a workflow, as similar as possible to conservation treatments on real artworks, to test a 3% w/v sodium oxalate treatment with two different application times, with or without limewater, on the coupons. The effectiveness of the treatments was analysed by comparison of surface properties by several NDT measurements. A statistical approach and XRD measurements directly on the corroded bronze surfaces are suggested as an effective way to characterise and compare the overall behaviour of bronze disease treatments for conservation.

Egyptian blue (EB) is amongst the first man-made pigments. Archaeological EB samples from Pozzuoli, Herculaneum and Pompei and modern EB mock-ups have been investigated by multianalytical approach: fibre optics reflectance spectroscopy (FORS), optical microscopy (OM), scanning electron microscopy with probe EDS (SEM-EDS) and particles induced X-ray emission (PIXE). To examine the effect of heating temperature and time on the properties of the produced pigment, modern EB samples were synthesized by varying firing temperature (850, 900, 950 degrees C) and time (tau = 1, 2 and 5 h). Some correlations, in terms of morphologic and colorimetric properties of produced material, related to the manufacturing temperature of firing are drawn. Moreover, the study confirms that there is a great variety of utilized substances linked to materials available for the manufacturer at the moment. (c) 2020 Elsevier Masson SAS. All rights reserved.

In order to achieve eco-friendly restorations, researchers and stone conservators are shifting towards low environmental impact biocides like plant natural extracts. The application of essential oils mixtures was tested in order to select and carry out a biocidal treatment on the Statue of Silvanus (National Archaeological Museum of Florence). Four essential oils (Coridothymus capitatus L., Syzigium aromaticum (L.) Merr. & L.M.Perry, Cinnamomum zeylanicum Blume and Origanum vulgare subsp. Hirtum Link Ietsw.) were chosen and blended, obtaining two different mixtures used for the treatment of the statue. They were applied by using three different carriers (agar-agar, Politect® and Carbogel) for ensuring a better biocide-patina contact. The poultice method allowed to use low concentrations and long times of application. This methodology required corrective actions, linked to the peculiarity of the stone masterpiece, like the pH adjustment of the compound. The results are an important precedent for the use of essential oils as biocidal treatment on outdoors stone heritage. In particular, the low concentration that have been used are non-toxic for humans and entail no environmental bioaccumulation. Moreover, the statue will be further constantly monitored in order to document the long lasting effect of the applied treatments.

The use of EO (essential oils) either alone or in mixture has become a very attractive option as a green method to remove biological infestation from outdoor stone, but it still needs research for defining the most appropriate conditions of application. The aim of this paper is to screen the effectiveness of seven plant EO (alone or in combinations) taking into account key factors for obtaining a satisfactory treatment, such as: (i) the proper concentration/application timing ratio and (ii) the best poultice to enhance the performance of EO. Several combinations of these factors were applied on a marble slab naturally colonized mainly by phototrophs. The assessment of the organisms vitality, as an indicator of the treatment efficiency, was tested by using two portable and non-invasive techniques with an immediate response: the autofluorescence of the phototrophic pigments and bioluminescence of the adenosine triphosphate (ATP) molecule. Microphotography and colour measurements were also used. The most efficient treatment was then successfully applied on a real marble statue (Archaeological Museum of Florence, Italy).

In this research, we propose an advanced system for the cleaning of wax-based coatings applied on indoor bronzes. To this aim we developed a new kind of eco-friendly gel based on PHB (poly-3-hydroxybutyrate) used as thickening agent, biodiesel (BD) and dimethyl carbonate (DMC). BD is a mixture of methyl esters obtained from palm oil, which acts as cleaning agent while DMC was added as additional solvent to partially solubilize PHB and forming a gelly phase. For the first time a PHB-based gel obtained by mixing two solvents with different proprieties was proposed, expanding the range of possible formulations, that can be used according to the specific restoration purpose. After the preliminary characterization of chemical and physical properties of the gel, an ad hoc analytical protocol was implemented to evaluate both the cleaning efficiency and the release of residues on the treated surfaces. Standard samples were prepared following ancient recipes and submitted to spectroscopic and chromatographic analysis before and after the cleaning procedures. Finally, the performances of PHB-DMC/BD gel were assessed on a real case of study presenting a wax-based coating: the Pulpito della passione attributed to Donatello and dated back to 1460. In situ analysis demonstrated the high cleaning efficiency of the proposed systems also for the removal of aged coatings.

Recently, the fine arts' research is increasingly carried out by non-invasive techniques, which do not require any sampling. However, some questions cannot be answered in this way. A typical example is the provenance analysis of the natural materials used in historical paintings. Another question is how much the provenance of the material is related to the provenance of the artwork itself (because of trade with pigments, painters' migration and their artistic preferences). Often, only painter's preference and intention are mentioned, and not economic factors and regional availability of the raw material. This is also the case of clay-based preparatory layers (grounds) on Caravaggio's paintings. In order to prove a connection of the ground composition with the place of the painting's creation, the painting grounds used by two prominent Baroque Masters Caravaggio and Mattia Preti have been investigated using X-ray powder micro-diffraction and Fourier transform infrared micro-spectroscopy in combination with micro-palaentological analysis. It was found that grounds applied by the same painter, but in two closely related regions – Italy and Malta, differ. While pottery clays were used in Italy, weathered Globigerina limestones were applied in Malta in combination with alunite-hematite material. It is the first time ever that such material has been identified as a main component in painting grounds.

studio smalti dell'Altare di San Giovanni, Firenze

UV Fluorescence microscopy is a powerful mean for visualizing and identifying structures in a specimen, and it has long been used in many applications, including pigment identification in artworks. Typical painting cross section samples are the result of multiple layers and especially for paintings produced from the thirteen to sixteen centuries, it is possible that for different pigments a different binder has been used, resulting in a complex stratification of materials. In this paper we propose a novel multispectral microscopy imaging system, which is specially designed for cultural heritage application, capable of acquiring both reflectance and fluorescence images in different wavebands, so to be able to document UV fluorescence emission and reflectance spectra.

The research complements a study (Pinna et al., 2012) carried out to evaluate the effectiveness of mixtures of consolidants and water-repellent products (tetraethylorthosilicate, methylethoxy polysiloxane, Paraloid B72), with biocides (tributyltin oxide, dibutyltin dilaurate, copper nanoparticles) applied in situ to prevent biological growth on stones. The mixtures were tested over time on trial areas of three substrates - marble, sandstone, and plaster – in the archaeological site of Fiesole (Firenze, Italy). The 8-year-long study showed that the recolonization of the three substrates after the conservation treatment related mainly to their bioreceptivity and to the climatic conditions. Although the mixtures of water repellents and consolidants with biocides and copper nanoparticles were effective in reducing the recolonization, they did not play a crucial role in preventing biofilms and lichens growth. This study demonstrated that it was not possible to draw common conclusions regarding the products’ performance on the examined stones. Copper nanoparticles proved to be a suitable alternative to traditional biocides because they did not alter stones colour and contributed to the prevention of recolonization. The study provided information on the succession of fungi and lichens on untreated and treated stones, as well as on the variations of water repellency of treated stones.

The research complements the complex study carried out to understand the source of brown discolourations of ten marble statues in the Church of Orsanmichele in Florence, Italy. Originally located in exterior niches, the statues were restored to reverse the extensive alterations they had undergone throughout the centuries. One of the major alterations was the application of a dark brown patina that dated just after 1789. After the statues were placed indoors, brownish discolourations started to appear on their surfaces. Cross sections were examined using FTIR mapping and immunological methods. In parallel, the pyrolysis-gas chromatography/mass spectrometry (py-GC/MS) data already obtained from the statues' scrapings were compared with data from aged casein films applied to microscope glass slides and aged milk-treated marble. All the statues had been treated with milk-based substances before the time the bronze patina was applied. The values of temperature and illumination of the room were important factors in the ageing of organic substances and in the formation of calcium oxalates. It is likely that products of thermo-oxidation and photo-oxidation of the oils together with the oxalates caused the darkening. The marble samples corresponded to a Lunense provenance.

The characterization of the surface morphology and the material layers stratigraphy is a pivotal step in several stages of the conservation process of the artwork. Generally, optimal characterization of the surface cannot be achieved using a single technique but is not always possible to find techniques that can be coupled effectively. Surface maps were retrieved using acoustic microscopy and conoscopic laser holography over a set of reference samples. The surface maps compared for showing possible way to better characterize the surface morphology when their information is combined. The final data give us a more complete surface and subsurface digitalization while the results obtained are discussed highlighting the main pros and cons of the two techniques. Thus besides having insights on the effectiveness and on the performance of the processes, it is also evident that uncertainties associated with the measurement can be overcome and a single more accurate representation of the surface can be derived using both scanning methods.

This study was completed within the framework of two research projects dealing with the conservation of contemporary artworks. The first is the Seventh Framework Project (FP7) of the European Union, Preservation of Plastic ARTefacts in Museum Collections (POPART), spanning years 2008–2012, and the second is the Italian project funded by the Tuscan Region, Preventive Conservation of Contemporary Art (Conservazione Preventiva dell'Arte Contemporanea (COPAC)), spanning 2011–2013. Both of these programs pointed out the great importance of having noninvasive and portable analytical techniques that can be used to investigate and characterize modern and contemporary artworks, especially those consisting of synthetic polymers. Indeed, despite the extensive presence of plastics in museum collections, there is still a lack of analytical tools for identifying, characterizing, and setting up adequate conservation strategies for these materials. In this work, the potentials of in situ and noninvasive Fourier transform infrared (FT-IR) spectroscopy, implemented by means of portable devices that operate in reflection mode, are investigated with a view to applying the results in large-scale surveys of plastic objects in museums. To this end, an essential prerequisite are the reliability of spectral data acquired in situ and the availability of spectral databases acquired from reference materials. A collection of polymeric samples, which are available commercially as ResinKit, was analyzed to create a reference spectral archive. All the spectra were recorded using three FT-IR configurations: transmission (trans), attenuated total reflection (ATR), and total reflection (TR). A comparative evaluation of the data acquired using the three instrumental configurations is presented, together with an evaluation of the similarity percentages and a discussion of the critical cases.

Laser-induced fluorescence is widely applied in several fields as a diagnostic tool to characterise organic and inorganic materials and could be also exploited for non-invasive remote investigation of wall paintings using the fluorescence lidar technique. The latter relies on the use of a low-fluence pulsed UV laser and a telescope to carry out remote spectroscopy on a given target. A first step to investigate the applicability of this technique is to assess the effects of low-fluence laser radiation on wall paintings. This paper presents a study devoted to investigate the effects of pulsed UV laser radiation on a set of fresco model samples prepared using different pigments. To irradiate the samples we used a tripled-frequency Q-switched Nd:YAG laser (emission wavelength: 355 nm; pulse width: 5 ns). We varied the laser fluence from 0.1 mJ/cm 2 to 1 mJ/cm 2 and the number of laser pulses from 1 to 500 shots. We characterised the investigated materials using several diagnostic and analytical techniques (colorimetry, optical microscopy, fibre optical reflectance spectroscopy and ATR-FT-IR microscopy) to compare the surface texture and their composition before and after laser irradiation. Results open good prospects for a non-invasive investigation of wall paintings using the fluorescence lidar technique.

The enamels of the Altar of San Giovanni, from the Baptistery of Florence, were investigated using both non-invasive and micro-invasive analysis in order to elucidate the glass melting and colouring techniques. A few fragments detached from the altar and recovered by the restorers were analysed in cross-section by electron probe microanalysis. Moreover, non-invasive investigations by portable XRF allowed a large number of enamelled plaques to be investigated. The results showed a good agreement between the two techniques and made it possible to identify similarities or differences in the enamels of the three manufacturing periods of the altar.

Five polychrome prints representing famous painters, such as Albrecht Durer, were analyzed using a non-destructive and non-invasive methodology as required by the artwork typology. The diagnostic strategy includes X-ray fluorescence (XRF), reflectance micro-infrared (μFTIR) and micro-Raman (μRaman) spectroscopy. These prints were realized with a la poupee method that involves application of the polychrome inks on a single copper plate, before the printing process. A broad range of compounds (i.e., cinnabar, red lead, white lead, umber earth, hydrated calcium sulfate, calcium carbonate, amorphous carbon, and Prussian blue) was employed as chalcographic inks, using linseed oil as a binding medium. Gamboge was identified in the delicate finishing brush touches realized in watercolor.

Fluorescence LIDAR imaging has been already proposed in several studies as a valuable technique for the remote diagnostics and documentation of the monumental surfaces, with main applications referring to the detection and classification of biodeteriogens, the characterization of lithotypes, the detection and characterization protective coatings and also of some types of pigments. However, the conservation and documentation of the cultural heritage is an application field where a highly multi-disciplinary, integrated approach is typically required. In this respect, the fluorescence LIDAR technique can be particularly useful to provide an overall assessment of the whole investigated surface, which can be profitably used to identify those specific areas in which further analytical measurements or sampling for laboratory analysis are needed. This paper presents some representative examples of the research carried out in the frame of the PRIMARTE project, with particular reference to the LIDAR data and their significance in conjunction with the other applied techniques. One of the major objectives of the project, actually, was the development of an integrated methodology for the combined use of data by using diverse techniques: from fluorescence LIDAR remote sensing to UV fluorescence and IR imaging, from IR thermography, georadar, 3D electric tomography to microwave reflectometry, from analytical techniques (FORS, FT-IR, GC-MS) to high resolution photo-documentation and historical archive studies. This method was applied to a 'pilot site', a chapel dating back to the fourteenth century, situated at 'Le Campora' site in the vicinity of Florence. All data have been integrated in a multi-medial tool for archiving, management, exploitation and dissemination purposes.

The paper describes the complex investigations carried out to understand the sources of the brown chromatic changes that have occurred on ten marble statues dated back to the first half of the 15th century and now located in the Church of Orsanmichele in Florence, Italy. When the statues were removed from the outdoor niches for restoration in the 1980s, they appeared covered with a dark brown patina (called ‘bronzatura’) that dated to interventions occurred just after 1789. Archival documents confirmed that they had been carried out to make the marble statues look like bronzes. Because of the removal of the dark patina carried out by the Opificio delle Pietre Dure in the 1990s, the marble almost regained its distinguishing clear tonality even if darker areas remained. After the statues were placed indoors at the end of restoration, brownish discolorations started to appear on their surfaces. Research began by using various non-invasive analyses (photographs under ultraviolet illumination, fluorescence lifetime imaging, x-ray fluorescence). The results of UV fluorescence tests and FLIM showed that the fluorescence emission’s distribution map does not have distinctive and homogeneous characteristics in relation to the areas with the discoloration. Therefore, it is not a superficial film, but rather a phenomenon affecting the marble structure. Then we performed invasive analyses on samples from some statues. The results of optical microscopy, ATR-FTIR and Raman spectroscopy on cross sections, pyrolysis-gas chromatography/mass spectrometry on powdered samples from the surfaces and/or the bulk of the marble allowed the identification of the various substances involved in the chromatic alteration. Most important was the detection of weddellite and gypsum on the surface and within the marble. This finding, combined with the presence of lipids inside the stone, suggests that mineralization of treatments have occurred, causing discolorations. Even though the study focuses on the statues from Orsanmichele, their issue nevertheless should not be considered specific to them. Marble discolorations are a widespread phenomenon whose complete understanding needs a complex series of analyses and only the combination of non-invasive and invasive analyses can fulfill this goal.

In order to identify the best practices and guidelines for the conservation of contemporary artworks, innovative approaches are needed, based on a monitoring campaign to assess the rate of alteration/decay of the objects placed outdoors. In this project, which is still in its first stage, the evolution in time of characteristic parameters is being used to establish thresholds for maintenance or restoration of three installations in the monumental garden of the “Fattoria di Celle”, located in Santomato (Pistoia, Italy). This garden hosts the Gori collection of 43 site-specific artworks created by contemporary artists. The three installations selected have different material compositions: bronze, stone and mortar painted with acrylic colors and glass. Each installation had its own conservation problems related to the constituent materials, together with the important impact of outdoor exposure and location. After a preliminary investigation, the major issues and risks for each artwork were identified and the monitoring campaign was started. Portable diagnostic tools and micro-sampling were used to monitor the parameters chosen. One year into the campaign, the preliminary diagnostic documentation has been realized, mainly for the bronze artistic object. Furthermore, the initial guidelines for monitoring campaigns have been defined.

This paper demonstrates that an educated methodology based on both non-invasive and micro invasive techniques in a two-step approach is a powerful tool to characterize the materials and stratigraphies of an Egyptian coffin, which was restored several times. This coffin, belonging to a certain Mesiset, is now located at the Museo Civico Archeologico of Bologna (inventory number MCABo EG 1963). Scholars attributed it to the late 22nd/early 25th dynasty by stylistic comparison. The first step of the diagnostic approach applied imaging techniques on the whole surface in order to select measurements spots and to unveil both original and restored areas. Images and close microscopic examination of the polychrome surface allowed selecting representative areas to be investigated in situ by portable spectroscopic techniques: X-ray Fluorescence (XRF), Fiber Optic Reflectance Spectroscopy (FORS) and Fourier Transform Infrared spectroscopy (FTIR). After the analysis of the results coming from the first step, very few selected samples were taken to clarify the stratigraphy of the polychrome layers. The first step, based on the combination of imaging and spectroscopic techniques in a totally non-invasive modality, is quite unique in the literature on Egyptian coffins and enabled us to reveal many differences in the ground layer's composition and to identify a remarkable number of pigments in the original and restored areas. This work offered also a chance to check the limitations of the non-invasive approach applied on a complex case, namely the right localization of different materials in the stratigraphy and the identification of binding media. Indeed, to dissolve any remaining doubts on superimposed layers belonging to different interventions, it was necessary to sample few micro-fragments in some selected areas and analyze them prepared as cross-sections. The original ground layer is made of calcite, while the restored areas show the presence of either a mixture of calcite and silicates or a gypsum ground, overlapped by lead white. The original pigments were identified as orpiment, cinnabar and red clay, Egyptian blue and green copper based pigments. Some other pigments, such as white lead, Naples yellow, cerulean blue and azurite were only found in the restored areas.

Laser-induced fluorescence technique is widely used for diagnostic purposes in several applications and its use could be of advantage for non-invasive on-site characterisation of pigments or other compounds in wall paintings. However, it is well known that long-time exposure to UV and VIS radiation can cause damage to wall paintings. Several studies have investigated the effects of lighting, e.g., in museums: however, the effects of low-fluence laser radiation have not been studied much so far. This paper investigates the effects of UV laser radiation using fluences in the range of 0.1 mJ/cm 2 –1 mJ/cm 2 on a set of a secco model samples prepared with lead white and different type of binders (animal glue and whole egg, whole egg, skimmed milk, egg-oil tempera). The samples were irradiated using a Nd:YAG laser (emission wavelength at 355 nm; pulse width: 5 ns) by applying laser fluences between 0.1 mJ/cm 2 and 1 mJ/cm 2 and a number of laser pulses between 1 and 500. The samples were characterised before and after laser irradiation by using several techniques (colorimetry, optical microscopy, fibre optical reflectance spectroscopy, FT-IR spectroscopy Attenuated Total Reflectance microscopy and gas chromatography/mass spectrometry), to detect variations in the morphological and physico-chemical properties. The results did not point out significant changes in the sample properties after irradiation in the proposed range of laser fluences.

The San Leonardo pulpit in Arcetri (12(th) century) is an unicum in Florence. The first documents place it in the Church of San Pier Scheraggio, from where it was moved in 1782 to the Church of San Leonardo in Arcetri. Inside the church the pulpit was again dismantled and reassembled in 1921 by Opificio delle Pietre Dure, with the addition of new parts. In this work, different restoration mortars have been characterized mineralogically by x-ray diffraction (XRD), chemically both by Fourier transform infrared spectroscopy (FT-IR) and by scanning electron microscopy (SEM-EDS), and petrographically by optical microscope observation in transmitted light (OM). Compositional data allow the research team to identify mortars related to different past interventions. Scientific results, with information obtained from historical sources, have been used in order to decide the selective removal of the materials that could give rise to further decay. Therefore mortars suitable for restoration were also developed by specific tests, in order to obtain materials compatible with the substrate by chemical, physical, and aesthetic point of view.

The formation of a spinel phase was observed after chromium deposition on a ZnO single crystal substrate and subsequent annealing. The structure of the spinel and its epitaxial relationship with the substrate were investigated by using X-ray photoelectron diffraction. Experimental data are discussed on the basis of a single scattering cluster-spherical wave model calculation. The presence of octahedrally coordinated Zn was ruled out and the deviation from stoichiometry is attributed to amorphous ZnO patches in the spinel matrix.

This study examines the structure of the surface alloys that form at the surface of the system formed by depositing cobalt on the clean Pt(111) surface. Using mainly XPD as a structure-sensitive technique, surface alloys were observed to form in this system after annealing at temperatures of about 600 K or higher. When starting with a single atomic layer of cobalt, diffusion leads to a surface phase where Pt atoms occupy mainly the topmost layer while cobalt atoms are mainly located in the second layer from the surface. Multi-atomic-layer alloying, with the formation of an epitaxial, random substitutional Co-Pt(111) alloy, is observed at higher temperatures.

Ultrathin cobalt films were deposited by thermal evaporation on the Pt(110) surface at room temperature. The growth mechanism was studied by a combination of low energy He + scattering (LEIS) and X-ray photoelectron spectroscopy (XPS). The results indicate that during the initial stages of growth cobalt forms a layer of single atomic thickness. X-ray photoelectron diffraction (XPD) shows that the multi-atomic layer cobalt film is ordered and has a well defined epitaxial relationship with the substrate.

Chloride layers of thickness of several atomic layers were prepared by low temperature reaction of Cl 2 with a clean Cu(001) surface. The structure of the chloride layer was examined by X-ray photoelectron diffraction (XPD). The results of the comparison of experimental XPD data and calculations carried out using the single scattering cluster-spherical wave (SSC-SW) model show that the chloride grows as epitaxial fcc, zincblende CuCl, with the (111) plane parallel to the substrate surface. The results also indicate that the (111) “chlorine” termination is the actual termination of the chloride phase, out of the two possible terminations of the polar zincblende structure.

Multi-atomic chloride layers are prepared on the clean Cu(100) surface by exposure to Cl 2 at 160 K at pressures of the order of 10 −3 Pa. The layer stoichiometry determined by XPS measurements corresponds to CuCl. Bringing the sample to room temperature, the layer undergoes a structural transformation where thicker islands are formed, while a fraction of the substrate surface becomes free. Exposure to radiation in the soft X-rays domain causes the photoreduction of the chloride layer and the formation of metallic copper. This metallic copper is located near or over the surface of the chloride.

After depositing a single atomic layer of cobalt on the Pt(111) surface, annealing at 600 K leads to the formation of a surface alloy of stable composition and structure. This phase was examined by crystallographic low energy electron diffraction finding that of the two topmost layers the first layer contains 20 at% of cobalt and the second one 80 at% of cobalt. No significant amounts of cobalt could be detected below the second atomic layer from the surface.

The atomic structure of the surface formed by depositing a single-atomic layer of cobalt on Pt (111) has been investigated using low-energy electron diffraction (LEED) crystallographic analysis. Cobalt grows at room temperature on the Pt (111) surface forming islands a single-atomic layer thick. The layer is ordered and it forms a 1×1 epitaxial phase where cobalt atoms are in an fcc registry with respect to the substrate.

The formation of surface alloys obtained by annealing ultrathin films of Sn deposited on the Pt(111) surface was investigated by low energy electron diffraction and X-ray photoelectron diffraction. The Pt(111)(2 × 2)-Sn and Pt(111)(√3 × √3)R30°-Sn form after deposition of amounts of Sn in the range from 0.2 to 1 ML and subsequent annealing at 1000 K are found by XPD to be single atomic layer surface alloys. Depositing 4–5 ML of Sn and annealing at 400–600 K produces an ordered phase exhibiting a (2 × 2) LEED pattern. This phase is a multilayer surface alloy and it has the same structure as the bulk Pt 3 Sn alloy.

The general abilty of photoelectron diffraction (XPD) to investigate the surface structure of oxides is shown. The actual termination of a ZnO single crystal is determined, oriented along the basal plane, distinguishing between the two possible (0001) and (000 1 ) polar surfaces. The collected XPD curves have been compared with theoretical calculations. For all the transitions examined, the features of the XPD azimuthal curves were found to repeat for a period of 60°, that is, the surface has an apparent sixfold symmetry which has been interpreted as being due to the presence of domains, separated by biatomic steps, equally distributed on the surface and rotated 60° with respect to each other. The existence of two surface domains rotated 60° was taken into account by averaging calculations for the two orientations. We tested two possible structural models, corresponding to the (0001) and to the (000 1 ) bulk termination structures, comparing the XPD azimuthal curves of the Zn 2p 3 2 , Zn 3p and O 1s transitions.

Cobalt was deposited on the clean Pt(111) surface at room temperature by thermal evaporation. The overlayer growth mechanism and structure was examined by X-ray photoelectron diffraction, combined with X-ray photoelectron spectroscopy and low energy He+ scattering. During the initial stages of growth cobalt forms a uniform layer of a single atomic layer thickness. Further growth results in the formation of an epitaxial fcc cobalt multilayer. Annealing at moderate temperature causes the formation of a fcc CoPt alloy of variable thickness.

The interaction of pigments and binding media may result in the production of metal soaps on the surface of paintings which modifies their visible appearance and state of conservation. To characterise more fully the metal soaps found on paintings, several historically accurate oil and egg yolk tempera paint reconstructions made with different pigments and naturally aged for 10 years were submitted to attenuated total reflectance Fourier transform infrared (ATR FTIR) microspectroscopic analyses. Standard metal palmitates were synthesised and their ATR spectra recorded in order to help the identification of metal soaps. Among the different lead-based pigments, red lead and litharge seemed to produce a larger amount of carboxylates compared with lead white, Naples yellow and lead tin yellow paints. Oil and egg tempera litharge and red lead paints appeared to be degraded into lead carbonate, a phenomenon which has been observed for the first time. The formation of metal soaps was confirmed on both oil and egg tempera paints based on zinc, manganese and copper and in particular on azurite paints. ATR mapping analyses showed how the areas where copper carboxylates were present coincided with those in which azurite was converted into malachite. Furthermore, the key role played by manganese in the production of metals soaps on burnt and raw sienna and burnt and raw umber paints has been observed for the first time. The formation of copper, lead, manganese, cadmium and zinc metal soaps was also identified on egg tempera paint reconstructions even though, in this case, the overlapping of the spectral region of the amide II band with that of metal carboxylates made their identification difficult.

Gold and gold−copper particles of sizes of the order of nanometers were prepared in reverse micelles, with different sizes of the water pool, by controlled chemical reduction of metal cations. The nanoclusters were characterized by a combination of dynamic light scattering (QELS), transmission electron microscopy, and X-ray photoelectron spectroscopy (XPS). The results indicate that it is possible to obtain a uniform or nearly uniform particle size distribution and that compound metallic nanoparticles of Cu3Au can be prepared by this method. At present we have no evidence on the mechanism that lead to mixing at the atomic level; nevertheless, it appears possible to exploit the method in order to prepare mixed bimetallic phases of various composition.

Wooden support: constituent materials, state of conservation, treatment of restoration and evaluation of their effectiveness.