Search

Four distinct classes of multiferroics are usually being discussed in the literature, in which ferroelectricity is respectively driven by electronic lone pairs, geometry, charge ordering, and magnetism. Each class has its own shortcomings for technological applications. Here, through a combined experimental and theoretical investigation, we propose a mechanism to achieve multiferroicity in a single phase by engineering the anionic network and creating local geometric distortions in fluorinated, vacancy-ordered brownmillerite Ca2Mn2O5−xFy. The system exhibits both ferroelectricity and an antiferromagnetic order above room temperature, pointing toward a novel route to multiferroicity by anion mixing.

Artemidorus papyrus has been the subject of a longstanding dispute around its authenticity. The 2.5 m long document, presents a multiplicity of writings, on both sides. Some historians support the papyrus’ multiple life hypothesis (PMLH): the different writings appearing on the document, would correspond to three time periods (1st BC–1st AD) called the “three lives of the papyrus”. A possible way to assess whether the document has been written in different eras, is the analysis of the graphic materials employed; a heterogeneous formulation of the inks used throughout the papyrus as a whole, together with a local homogeneity in defined regions, would support PMLH. To unveil this paradigm, we performed an in-depth investigation of the inks on the papyrus, by collecting their Raman spectra on a statistical relevant number of samples belonging to the different regions of the document. We found a wide variety of carbon-based inks that appear to be randomly distributed on the entire surface. Different ordered, disordered, crystalline or amorphous structures might coexist in carbon-based materials, due to the different hybridisations of the carbon. All of the different structures appear as peaks, shoulders or sub peaks that are convoluted in the global spectrum, thus rendering the attribution of Raman peaks as an extremely complex task. In order to support and guide our analysis, we therefore implemented a Principal Component Analysis (PCA) aimed at performing a two-step comparison between the Artemidorus inks Raman spectra and an ample reference spectral library on carbon-based materials that we built specifically for this study. A first PCA screening was used to restrict the analysis for similarity between the experimental spectra and the library of standards to a subset of compounds. It was indeed possible to define a cluster in the Principal Component subspace that contained only a few standards and the whole set of Artemidorus spectra. It is interesting to notice that, among the possibilities in the reference library, our analysis also found two pigments manufactured with modern industrial methods: Carbon black (after 1870) and lampblack (after 1740, modified in 19th c.). A second PCA, performed on the subset of the standard spectra individuated, allowed to highlight the regions of the Raman spectra where the Artemidorus data depict significant differences with respect to their reference standards, thus allowing for a guided deconvolution of the Raman peaks. This study demonstrates that it is not possible to define neat regions on the papyrus that would be identifiable through the usage of different groups of inks, as the same subset of inks is distributed on all of the document. It is therefore impossible to recognise areas of the papyrus where the local usage of specific and region-dependent graphic materials would lead to chronologically distinguishable writings and drawings. This allows us to confute the “three lives hypothesis”.

In this work, the electronic and molecular structure, as well as the morphology, of innovative nanostructured materials whose optical properties respond to the presence of heavy metals in water samples was investigated. In particular, the here discussed silver nanoparticles (NPs) stabilized by a hydrophilic ligand (sodium 3-mercapto-1-propanesulfonate, 3MPS) are able to reveal the presence of mercury ions at ppm levels. The sensitivity of the proposed nanosensor to Hg(II) in 1-5 ppm range was ascertained by optical tests; then, the local chemistry and electronic structure of the nanostructured coordination compounds made of functionalized silver nanoparticles (NPs) and metal ions, and their correlation with the resulting nanoaggregates' shape and morphology, were investigated by state-of-the-art synchrotron radiation (SR)-induced spectroscopies and transmission electron microscopy (TEM). In particular, SR-induced X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) measurements allowed us to gather complementary information about the silver-mercury interaction, which is only partially mediated by the negatively charged 3MPS ligand, different from what was observed for analogous nanosensors applied to other bivalent heavy metal ions, for example, Co(II) and Ni(II). TEM morphological analysis sheds light on the structure of the AgNP-3MPS/Hg aggregates, revealing the formation of Ag/Hg alloy nanoparticles.

Physica status solidi / B 259(4), 2100513 (2022). doi:10.1002/pssb.202100513, The surface region of austenitic stainless steel (SS) is investigated by synchrotronX-ray powder diffraction (XRPD) and X-ray absorption near edge structure (XANES)measurements, because its composition and structure are crucial for the corrosionresistance of SS. Grazing incidence XRPD of a polished AISI 304 bulk steel sampleshows that the near-surface structure is modified. The concentration of the ferritephase of Fe, a typical minority phase in AISI 304, increases gradually from 10% to30% when approaching the surface from 150 nm depth. XANES Fe K-edgeinvestigations of ultrathin, sputter-deposited films also reveal much larger ferritefractions than expected from the austenitic steel composition of the films. Reasonsfor the increased ferrite fraction in the surface region of bulk steel and thin films arediscussed. However, right at the surface, the trend reverses. Analysis of XANES datafor an ultrathin, 4 nm SS film shows that 80% of Fe is oxidized and 20% of metallicFe is present only in austenite structure, suggesting that ferritic iron is preferentiallysubject to oxidation. The austenitic Fe is located at more than 2–3 nm below thesurface where the Ni concentration is >10%., Published by Wiley-VCH, Weinheim

Bis(pyrazol-1-yl)- and bis(3,5-dimethylpyrazol-1-yl)-acetates were conjugated with the 2-hydroxyethylester and 2-aminoethylamide derivatives of the antineoplastic drug lonidamine to prepare Cu(I) and Cu(II) complexes that might act through synergistic mechanisms of action due to the presence of lonidamine and copper in the same chemical entity. Synchrotron radiation-based complementary techniques [X-ray photorlectron spectroscopy and near-edge X-ray absorption fine structure (NEXAFS)] were used to characterize the electronic and molecular structures of the complexes and the local structure around the copper ion (XAFS) in selected complexes. All complexes showed significant antitumor activity, proving to be more effective than the reference drug cisplatin in a panel of human tumor cell lines, and were able to overcome oxaliplatin and multidrug resistance. Noticeably, these Cu complexes appeared much more effective than cisplatin against 3D spheroids of pancreatic PSN-1 cancer cells; among these, PPh3-containing Cu(I) complex 15 appeared to be the most promising derivative. Mechanistic studies revealed that 15 induced cancer cell death by means of an apoptosis-alternative cell death.

We have investigated magnetic, structural and dielectric properties of Bi

The conservation of underground tombs is affected by several physical-chemical and biological factors, which could be reduced by insulating systems able to maintain the microclimatic stability also decreasing the biodeterioration risk. In Mediterranean areas, wild ephemeral plants, which reduce their cover during the hot season, seem unsuitable for reducing summer overheating. In this study, we wish to assess the influence of vegetation cover and of overlaying soil, after the establishment of an evergreen turf of a cultivar of Cynodon dactylon, on two tombs in the Etruscan Necropolis of Monterozzi, covered by linear-shaped tumuli. Therefore, we evaluated for 10 months the thermo-hygrometric values of these tombs, together with two tombs as controls. We also evaluated the different tumuli’s morphologies and the related received solar radiation. Results confirmed that late summer and early autumn as critical microclimatic periods for the risk factors of hypogeal paintings when peaks of superficial temperature occur. A positive influence of vegetation cover on maintaining constant humidity and internal temperatures was detected, but the mounds orientation, as well as soil depth, seems to have a relevant role. Considering the naturalistic features of the area and the related cultural ecosystem services, a careful selection of wild plants is suggested.

Colossal electroresistance (CER) in manganites, i.e., a large change in electrical resistance as a function of varying applied electric field or applied electric current, has often been described as complimentary to the colossal magnetoresistance (CMR) effect. Mixed valence vanadates with active ${t}_{2g}$ and empty ${e}_{g}$ orbitals, unlike manganites, have not naturally been discussed in this context, as double exchange based CMR is not realizable in them. However, presence of coupled spin and orbital degrees of freedom, metal-insulator transition (MIT) accompanied by orbital order-disorder transition, still make the vanadates important. Here we probe a Fe-doped hollandite lead vanadate $\mathrm{Pb}{\mathrm{Fe}}_{1.75}{\mathrm{V}}_{4.25}{\mathrm{O}}_{11}$ (PFVO), which exhibits a clear MIT as a function of temperature. Most importantly, a giant fall in the resistivity, indicative of a CER, as well as a systematic shift in the MIT towards higher temperatures are observed with increasing applied current. Detailed structural, magnetic, thermodynamic, and transport studies point towards a complex interplay between the structural distortion, orbital order/disorder effect, and the resultant MIT and magnetic ordering in this system.

Biominerals are widespread in Nature and they precipitate to respond to different physiological purposes. A broad knowledge of their chemical and structural properties offers a unique opportunity to improve our capability to reconstruct actual and paleoenvironment. In this work, we show two case studies, bivalves and foraminifera grown in polluted sites that were characterized by applying different and complementary synchrotron radiation-based investigation techniques, mainly focused on the investigation of Zn incorporation in the biomineralized shells. Using scanning transmission X-ray microscopy (STXM) and X-ray micro-fluorescence (µ-XRF), we found the colocalization of elements across the shells, while we obtained information on chemical speciation of Zn by applying X-ray absorption spectroscopy (XAS). Noticeably, instead of metal dispersion in the Ca-carbonate shells, we found traces of several independent phases, in particular for Zn, dispersed generally as microscopic minerals. This work provides fundamental insight into the structural properties, coordinative and chemical environment of some marine biominerals. This new knowledge is fundamental to understand the biogeochemical processes and to develop effective environmental proxies.

This work reports about a novel approach for investigating surface processes during the early stages of galvanic corrosion of stainless steel in situ by employing ultra-thin films and synchrotron x-radiation. Characterized by x-ray techniques and voltammetry, such films, sputter deposited from austenitic steel, were found representing useful replicas of the target material. Typical for stainless steel, the surface consists of a passivation layer of Fe- and Cr-oxides, a couple of nm thick, that is depleted of Ni. Films of ≈4 nm thickness were studied in situ in an electrochemical cell under potential control (−0.6 to +0.8 V vs Ag/AgCl) during exposure to 0.1 M KCl. Material transport was recorded with better than 1/10 monolayer sensitivity by x-ray spectroscopy. Leaching of Fe was observed in the cathodic range and the therefor necessary reduction of Fe-oxide appears to be accelerated by atomic hydrogen. Except for minor leaching, reduction of Ni, while expected from Pourbaix diagram, was not observed until at a potential of about +0.8 V Cr-oxide was removed from the steel film. After couple of minutes exposure at +0.8 V, the current in the electrochemical cell revealed a rapid pitting event that was simultaneously monitored by x-ray spectroscopy. Continuous loss of Cr and Ni was observed during the induction time leading to the pitting, suggesting a causal connection with the event. Finally, a spectroscopic image of a pit was recorded ex situ with 50 nm lateral and 1 nm depth resolution by soft x-ray scanning absorption microscopy at the Fe L2,3-edges by using a 80 nm film on a SiN membrane, which is further demonstrating the usefulness of thin films for corrosion studies.

A new multielement X-ray fluorescence detector is presented, specifically designed to probe the chemical speciation of trace 3d elements down to the p.p.m. range., X-ray absorption fine-structure (XAFS) spectroscopy can assess the chemical speciation of the elements providing their coordination and oxidation state, information generally hidden to other techniques. In the case of trace elements, achieving a good quality XAFS signal poses several challenges, as it requires high photon flux, counting statistics and detector linearity. Here, a new multi-element X-ray fluorescence detector is presented, specifically designed to probe the chemical speciation of trace 3d elements down to the p.p.m. range. The potentialities of the detector are presented through a case study: the speciation of ultra-diluted elements (Fe, Mn and Cr) in geological rocks from a calcareous formation related to the dispersal processes from Ontong (Java) volcanism (mid-Cretaceous). Trace-elements speciation is crucial in evaluating the impact of geogenic and anthropogenic harmful metals on the environment, and to evaluate the risks to human health and ecosystems. These results show that the new detector is suitable for collecting spectra of 3d elements in trace amounts in a calcareous matrix. The data quality is high enough that quantitative data analysis could be performed to determine their chemical speciation.

The physical properties of nanostructured thin films and multilayers depend crucially on their interfaces. The precise knowledge of the interface morphology at the atomic scale is mandatory to reliably understand their macroscopic response. These details become even more critical when dealing with magnetic thin films as the finest structural and/or compositional local changes may affect the magnetic coupling and alter the macroscopic response. Soft X-ray Resonant Magnetic Reflectivity (SXRMR) is a suitable technique in this field, combining specific aspects of x-ray absorption and x-ray scattering processes to simultaneously obtain complementary structural and magnetic information on thin films and multilayers. Here, we present a case study on a MgO/Co/MgO trilayer in which the combined use of SXRMR, x-ray absorption spectroscopy and x-ray magnetic circular dichroism has allowed to reconstruct the elemental and magnetic depth profiles with sub-nanometric resolution and to distinguish fine compositional defects at the Co-on-MgO and MgO-on-Co interfaces.

Synthesis atmosphere (i.e., air and nitrogen) effects on the physical properties and formation mechanism of spinel iron oxide nanoparticles prepared via the co-precipitation method have been investigated using a multi-technique approach. The obtained magnetic nanoparticles (MNPs) were characterized using the X-ray diffraction, transmission electron microscopy (TEM), SQUID magnetometry, Mössbauer spectroscopy and X-ray absorption near-edge Structure spectroscopy techniques. The synthesis procedure leads to the formation of a spinel structure with an average crystallite size of 9.0(9) nm. The morphology of the particles synthetized under an inert atmosphere was quasi-spherical, while the nanoparticles prepared in air present a faceted shape. The small differences observed in morphological properties are explained by the influence of the reaction atmosphere on the formation mechanism of the MNPs. The magnetic characterization indicates that both samples exhibit superparamagnetic behavior at 300 K. The investigation by means of the Langevin approach at 300 K also leads to equal values for the mean size of the magnetic cores (Dm). Additionally, the analysis of the Mössbauer spectra revealed the lack of spin disorder for both samples, resulting in a high saturation magnetization. The fit of XANES spectrum suggests that about 2/3 of the iron ions reside in a local environment close to that of γ-Fe2O3 and about 1/3 close to that of Fe3O4 for the sample synthetized in inert atmosphere.

To understand the fate of plastic in oceans and the interaction with marine organisms, we investigated the incorporation of (bio)polymers and microplastics in selected benthic foraminiferal species by applying FTIR (Fourier Transform Infrared) microscopy. This experimental methodology has been applied to cultured benthic foraminifera Rosalina globularis, and to in situ foraminifera collected in a plastic remain found buried into superficial sediment in the Mediterranean seafloor, Rosalina bradyi, Textularia bocki and Cibicidoides lobatulus. In vitro foraminifera were treated with bis-(2-ethylhexyl) phthalate (DEHP) molecule to explore its internalization in the cytoplasm. Benthic foraminifera are marine microbial eukaryotes, sediment-dwelling, commonly short-lived and with reproductive cycles which play a central role in global biogeochemical cycles of inorganic and organic compounds. Despite the recent advances and investigations into the occurrence, distribution, and abundance of plastics, including microplastics, in marine environments, there remain relevant knowledge gaps, particularly on their effects on the benthic protists. No study, to our knowledge, has documented the molecular scale effect of plastics on foraminifera. Our analyses revealed three possible ways through which plastic-related molecules and plastic debris can enter a biogeochemical cycle and may affect the ecosystems: 1) foraminifera in situ can grow on plastic remains, namely C. lobatulus, R. bradyi and T. bocki, showing signals of oxidative stress and protein aggregation in comparison with R. globularis cultured in negative control; 2) DEHP can be incorporated in the cytoplasm of calcareous foraminifera, as observed in R. globularis; 3) microplastic debris, identified as epoxy resin, can be found in the cytoplasm and the agglutinated shell of T. bocki. We hypothesize that plastic waste and their associated additives may produce modifications related to the biomineralization process in foraminifera. This effect would be added to those induced by ocean acidification with negative consequences on the foraminiferal biogenic carbon (C) storage capacity.

In recent years the biomedical research has focused on new metal-based anticancer drugs. Among them Cu-based antitumor agents are arising some attention based on the observation that endogenous metals appear to be less toxic toward normal cells with respect to cancer ones. Conjugating the Cu(II) complexes with hydrophilic gold nanoparticles (Au-NPs) appears a promising way, suitable to improve the complexes solubility and stability in water and to raise their bioavailability. In this context, we investigated the valence state and coordination chemistry of Cu for a selection of Cu-complexes suitable for grafting on Au-NPs. The Cu K-edge XAFS data were analysed in the near edge (XANES) and extended (EXAFS) regions to obtain preliminary characterization aimed at understanding local coordination chemistry and electronic structure of Cu.

This work reports about a novel approach for investigating surface processes during the early stages of galvanic corrosion of stainless steel

Mining activity is cause of deep landscape morphology modifications and often leaves critical legacy represented by huge volumes of mine wastes and residues of metallurgical processes. These wastes are usually made up by highly reactive materials which lead to the mobilization and dispersion of harmful elements in soils and waters, up to several kilometers from the source of contamination, representing a serious threat for health of humans, animals and environment.The Iglesiente and Arburese mine districts, in South West Sardinia (Italy), have been interested by intensive mine exploitation lasting for centuries. The mine activity was mainly addressed to zinc (Zn) and lead (Pb) extraction from primary sulphides and secondary non-sulfide mineralizations (calamine ores). After the mine closure (1968−1995), no real actions addressed to mitigate the environmental impact have been adopted; therefore, either surface or underground waters can interact with minerals present in the flooded adits, mining wastes and tailings, causing the mobilization and dispersion of high amounts of contaminants.Several studies have been carried out to understand the processes ruling the fate of metals, with particular interest for Zn, the most important contaminant of the study areas. Results of hydrological tracer techniques show that the Zn load of the investigated rivers differs up to 3 orders of magnitude, from about 6 kg/day (Rio San Giorgio) up to about 2000 kg/day (Rio Irvi). These differences do not seem to be linked to a substantially different discharge, but appear to be related to the peculiarity of each river in terms of riverbed morphology, vegetal coverage, water flow and sedimentation/erosional rates, that may favor, in the hyporheic zone, the onset and development of processes limiting the metal mobility. For example, scanning electron microscopy (SEM) analyses of core sample collected from the riverbed has shown the presence of metal sulphides (FeS2, ZnS) attributable to the supergene formation of secondary phases promoted by the microbial sulphate reduction. Moreover, the metal intake/immobilization in roots and stems of plants (e.g. Phragmites australis and Juncus acutus) and in their rizosphere, have been observed.These processes constitute natural biogeochemical barriers, that can effectively limit the metal dispersion and whose understanding can help in planning effective remediation strategies. The authors acknowledge CESA (E58C16000080003) from RAS and RAS/FBS (F72F16003080002) grants, FP7 ERANETMED2 72094 SUPREME, the Grant of Excellence Departments, MIUR (ARTICOLO 1, COMMI 314 – 337 LEGGE 232/2016), the CeSAR (Centro Servizi d'Ateneo per la Ricerca) of the University of Cagliari, Italy, for SEM analysis, and the POR FESR Sardegna 2014-2020 (project cluster Top-Down: TESTARE)

Mining activities generate a large amount of waste materials that are often very unstable and represent a source of pollution. Phytomanagement, in terms of phytostabilization, is considered a suitable method to decrease environmental risks of metal-enriched mine wastes (Parraga-Aguado et al. 2013). This technique employs plants to achieve the surface stabilization of the wastes by acting as a barrier which decreases wind borne dust and water erosion, reduces metal-enriched leaching through metal accumulation in plant roots and provides metal immobilization in the rhizosphere (Robinson et al. 2009; Sun et al. 2016).Most of the research has focused on the selection of the best spontaneously adapted plant species (endemic pioneer plants) for each specific mining site (Parraga-Aguado et al. 2013), because they may respond better and can survive easily compared to introduced alien species (Bradshaw 1997; Pandey 2015). Pioneer vegetation may improve edaphic conditions by increasing soil nutrient content (Rodríguez et al. 2007) or ameliorating soil acidity (Rufo and de la Fuente 2010), and thus may favor further establishment of other plant species.The investigation of metal transfer from the geosphere to the vegetal tissues helps to understand the adaptive strategies of plant species and may be useful for soil remediation actions. Synchrotron radiation-based techniques represent the state of the art tools to investigate the microscopic processes occurring in plant-soil systems (Kopittke et al. 2017). X-ray diffraction, X-ray fluorescence and X-ray absorption spectroscopy (XAS), are particularly suited to determine the finest complementary details about the atomic and crystallographic structure, distribution of elements, their chemical speciation and their valence state. Here, we report a review of selected researches performed on different plant species (Pistacia lentiscus L., Euphorbia pithyusa subsp. cupanii, Phragmites australis, and Helichrysum microphyllum Cambess. subsp. tyrrhenicum), growing on metal contaminated substrates in abandoned mining areas in Sardinia (Italy).Our results demonstrate that these plant species have developed their own adaptation strategy to grow and to survive in polluted environments, making them potential candidates to develop low-cost and self-sustainable vegetative covers aimed at reducing the dispersion of metals in soils and waters around these mine polluted sites.AcknowledgmentsThe authors acknowledge CESA (E58C16000080003) from RAS and RAS/FBS (F72F16003080002) grants, FP7 ERANETMED2 72094 SUPREME, the POR FESR Sardegna 2014-2020 (project cluster Top-Down: TESTARE), the Grant of Excellence Departments, MIUR (ARTICOLO 1, COMMI 314 – 337 LEGGE 232/2016), and the CeSAR (Centro Servizi d'Ateneo per la Ricerca) of the University of Cagliari, Italy, for SEM analysis.ReferencesA. Bradshaw, Ecol. Eng. 8, 255 (1997).P.M. Kopittke et al., J. Environ. Qual. 46, 1175 (2017).V.C. Pandey, Ecol. Eng. 82, 1 (2015).I. Parraga-Aguado et al., Environ. Pollut. 176, 134 (2013).B.H. Robinson et al., CRC. Crit. Rev. Plant Sci. 28, 240 (2009).N. Rodríguez et al., Arid L. Res. Manag. 21, 51 (2007).L. Rufo and V. de la Fuente, Arid L. Res. Manag. 24, 301 (2010).Z. Sun et al., Ecol. Eng. 86, 60 (2016).

This paper outlines a method of extraction of iron from water in the form of iron oxyhydroxide natural nanoclusters at comparatively low concentrations and varied ranges of pH using zinc acetate salt. The zinc acetate salt dissociates into Zn2+ and acetate ions in water where Zn2+ interacts with iron clusters present in a solution of a given iron concentration and pH, while the acetate ion helps in charge-neutralization based coagulation and consequent precipitation of such nanoclusters. The Zn2+ ions may also lead to the growth of layered zinc hydroxide (LZH) nanosurfaces at pH ≥ 6 at sufficient loading. The advantage of this method is the active chemical interaction of Zn2+ with Fe clusters, followed by growth, which ensures that only some added Zn ions remain in the water while the rest precipitate out along with the residual iron oxyhydroxide, especially at higher pH. The solid that precipitated under various different conditions was successfully evaluated by XRD (formation of ferrihydrite-like nanoclusters (n-Fh)), FTIR (the presence of acetate in the solid n-Fh), TEM (the presence of zinc at higher pH), and EXAFS (local structural characterization). ICP analysis of the obtained solid and the corresponding filtrate revealed the removal efficiency of iron and zinc from the solution at various initial concentrations and pH values. This method of extracting soluble Fh-like nanoclusters by charge neutralization appears to be a suitable promising tool for water purification, because ferrihydrite is capable of isolating other adsorbed contaminants from water, along with itself. This journal is

In this study, two new hexyl bis(pyrazol-1-yl)acetate ligands and related copper(ii) complexes were prepared and fully characterized in the solid state and in solution. Their electronic and molecular structures were investigated by X-ray photoelectron spectroscopy and near edge X-ray absorption; their ligand molecular structural stability upon coordination to copper was also investigated. The Cu(ii) complexes were studied as new catalysts in copper-catalyzed C-H oxidation for allylic functionalization (the Kharasch-Sosnovsky reaction) avoiding the use of any external reducing agents. Using 5 mol% of these catalysts and tert-butylperoxybenzoate as the oxidant, allylic benzoates were obtained in up to 90% yield: the general reaction time was decreased to 6 h and a 5 to 1 ratio of the alkene and tert-butylperoxybenzoate was used to overcome the two most important limitations on their use in chemistry.

Physica status solidi / B Basic research 257(6), 2000055 - (2020). doi:10.1002/pssb.202000055, An ≈4 nm FeCrNi film, deposited on a Ru/B$_4$C multilayer (ML), is used to study cathodic hydrogen charging in electrolyte. A thin film on a ML allows obtaining precise quantitative information on surface metal composition and oxidation state using the X‐ray standing wave technique combined with near‐edge X‐ray absorption spectroscopy. The metal composition is found being close to the composition of stainless steel (SS) 304, and, as for bulk steel, the outer 2 nm passive layer, consisting of oxidized iron and chromium, is depleted of nickel. Overall, it is found that the film represented a useful replica of the surface of bulk steel. Following exposure to 0.1 $_M$ KCl electrolyte at −0.6 V versus Ag/AgCl, 11.3 (±3)% swelling of the film by hydrogen absorption is observed. The estimated absorbed amount is exceeding reported bulk absorption under similar conditions by more than an order of magnitude. Strong hydrogen absorption appears to be enabled by the 2D character of the thin film, i.e., a significantly lower associated strain energy compared with bulk absorption. The strong surface swelling is suggested to be related to the lowering of the pitting corrosion resistance of SS surfaces reported following hydrogen exposure., Published by Wiley-VCH, Weinheim

The local atomic structure and the magnetic response of Co films intercalated between Graphene and Ir(111) were investigated combining polarized X-ray Absorption Spectroscopy at the Co K edge with Magneto-Optic Kerr Effect. The structural and magnetic evolution upon a 500 ° C annealing was evaluated as a function of the film thickness. After the thermal treatment, our thick film (10 monolayers) presented a lower perpendicular magnetic anisotropy (PMA) as well as a reduced average structural disorder. On the other hand, in our thin film (5 monolayers), the annealing enhanced the perpendicular magnetic response and induced a local anisotropy by stretching the Co-Co bonds in the film plane and compressing those outside the plane. Our finding emphasizes the close relationship between the local structure of Co within the film and its magnetic properties.

Cement-based stabilization is a widespread technique used for the treatment of contaminated soils. Despite its established application, the mechanisms involved in the stabilization of contaminants are not fully understood yet. This work aims to elucidate the fate of a real Pb contaminated soil amended with different binders, by studying Pb local environment prior and after the stabilization process. The study of a complex historically contaminated soil was coupled with the investigation of simplified artificial systems, developed to model Pb local structure in the unknown newly formed hybrid systems of soil and binders. The use of synchrotron-based element-specific X-ray absorption spectroscopy (XAS) permitted to probe the actual transformation of Pb environment in the real contaminated soil after the stabilization process. With the support of the model systems, we can propose as the main mechanism involved in Pb retention in sulfated soil treated with cement, the incorporation and/or adsorption of Pb on calcium silicate hydrates and ettringite.

Thin Co films intercalated between a Graphene capping layer and the Ir(111) surface are of interest for spintronics applications due to their peculiar magnetic properties and to their chemical stability. The structure, and then the magnetic properties, of the Co films depend on the intercalation process which is strongly influenced by the temperature, total amount of Cobalt and quality of the capping Graphene layer. In order to identify and disentangle the effects of these contributions, we report on the structural characterisation of four Co films as a function of thickness, annealing temperature, and Graphene capping. From the structural point of view, the deposition of Co on a hot Ir substrate mimics quite well the intercalation process proving the validity of the colander model describing the Graphene role during the process.