B22-Multimode InfraRed imaging And Microspectroscopy
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Open Access
Abstract: Fourier-transform infrared (FTIR) spectroscopy is a widespread and highly sensitive analytical method for the identification and characterization of a wide range of materials via their infrared (IR) absorption bands. Until now, the potential of IR microspectroscopy and imaging for the characterization of works of art or other objects of cultural heritage significance has been only partially exploited; in particular the use of the synchrotron radiation (SR) IR microprobe to study, at the micron scale, materials of interest for archaeological and cultural heritage studies has become popular only in the past decade. One of the main requirements imposed on the studies of ancient and/or valuable materials is that the techniques applied must be non-destructive. In this scenario, SRbased FTIR methods are perfectly suitable. Moreover, IR spectroscopy and imaging are emerging techniques that combine the assets of IR in terms of molecular specificity with the unique properties of synchrotron light. SR-FTIR micro-spectroscopy offers great advantages over conventional methods because it provides a broader spectrum (down to THz) and higher spectral quality (signal/noise ratio) at the highest spatial resolution (diffraction limited). This is due to the high brilliance and collimation of SR-IR, while still being non-damaging to the investigated system. The unique SR-IR parameters are essential for the compositional analysis of the tiny, sub-millimetric samples characteristic of ancient materials, which are heterogeneous by nature, and with complex molecular distributions at extremely variable concentrations. SR-FTIR spectroscopy and imaging can be applied successfully to the characterization of organic and inorganic materials via so-called IR fingerprinting, as well as for their compositional quantification. The range of materials investigated is very broad and encompasses painting materials, stones, glasses, ceramics, coatings on metals, paper and wooden materials, canvas or other textiles, organic colourants, resins, varnishes, cosmetics, and binding media such as glues, waxes, oils, etc. SR-IR-based methods can also be used to understand the historical technologies and to identify the raw materials used to produce archaeological artefacts and art objects, and to improve stabilization, conservation and restoration practices. Selected applications of SR-FTIR methods are discussed with a special emphasis on the chemical and mineralogical characterization of ancient paintings, on the study of alteration and corrosion layers, and the separation and identification of pigments. New perspectives offered by existing facilities and new developments in IR imaging and advanced vibrational spectroscopy that may broaden the variety of archaeological and historical materials that may be studied are outlined.
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Jul 2019
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B18-Core EXAFS
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Giannantonio
Cibin
,
Augusto
Marcelli
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Valter
Maggi
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Giovanni
Baccolo
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Dariush
Hampai
,
Phillip E.
Robbins
,
Andrea
Liedl
,
Claudia
Polese
,
Alessandro
D'elia
,
Salvatore
Macis
,
Antonio
Grilli
,
Agostino
Raco
Diamond Proposal Number(s):
[7314, 8372, 9050]
Open Access
Abstract: Airborne dust extracted from deep ice core perforations can provide chemical and mineralogical insight into the history of the climate and atmospheric conditions, with unrivalled temporal resolution, time span and richness of information. The availability of material for research and the natural complexity of the particulate, however, pose significant challenges to analytical methods. We present the developments undertaken to optimize the experimental techniques, materials and protocols for synchrotron radiation-based analysis, in particular for the acquisition of combined Synchrotron Radiation X-Ray Fluorescence and X-ray Absorption Spectroscopy data.
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Jun 2019
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Open Access
Abstract: Structural changes of MoO3 thin films deposited on thick copper substrates upon annealing at different temperatures were investigated via ex situ X-Ray Absorption Spectroscopy (XAS). From the analysis of the X-ray Absorption Near-Edge Structure (XANES) pre-edge and Extended X-ray Absorption Fine Structure (EXAFS), we show the dynamics of the structural order and of the valence state. As-deposited films were mainly disordered, and ordering phenomena did not occur for annealing temperatures up to 300 °C. At ~350 °C, a dominant α-MoO3 crystalline phase started to emerge, and XAS spectra ruled out the formation of a molybdenum dioxide phase. A further increase of the annealing temperature to ~500 °C resulted in a complex phase transformation with a concurrent reduction of Mo6+ ions to Mo4+. These original results suggest the possibility of using MoO3 as a hard, protective, transparent, and conductive material in different technologies, such as accelerating copper-based devices, to reduce damage at high gradients.
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Apr 2019
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B18-Core EXAFS
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Salvatore
Macis
,
Carla
Aramo
,
Carmela
Bonavolontà
,
Giannantonio
Cibin
,
Alessandro
D'elia
,
Ivan
Davoli
,
Mario
De Lucia
,
Massimiliano
Lucci
,
Stefano
Lupi
,
Marco
Miliucci
,
Andrea
Notargiacomo
,
Carlo
Ottaviani
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Claudio
Quaresima
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Manuela
Scarselli
,
Jessica
Scifo
,
Massimo
Valentino
,
Paola
De Padova
,
Augusto
Marcelli
Abstract: In this work, the authors investigated MoO3 films with thickness between 30 nm and 1 μm grown at room temperature by solid phase deposition on polycrystalline Cu substrates. Atomic force microscopy, scanning electron microscopy, and scanning tunneling microscopy revealed the presence of a homogenous MoO3 film with a “grainlike” morphology, while Raman spectroscopy showed an amorphous character of the film. Nanoindentation measurements evidenced a coating hardness and stiffness comparable with the copper substrate ones, while Auger electron spectroscopy, x-ray absorption spectroscopy, and secondary electron spectroscopy displayed a pure MoO3 stoichiometry and a work function ΦMoO3 = 6.5 eV, 1.8 eV higher than that of the Cu substrate. MoO3 films of thickness between 30 and 300 nm evidenced a metallic behavior, whereas for higher thickness, the resistance–temperature curves showed a semiconducting character.
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Mar 2019
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B18-Core EXAFS
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Diamond Proposal Number(s):
[1984]
Open Access
Abstract: X-ray absorption near edge structure (XANES) measurements at the Fe K-edge were performed on aeolian dust in the TALos Dome Ice CorE drilling project (TALDICE) ice core drilled in the peripheral East Antarctic plateau, as well as on Southern Hemisphere potential source area samples. While South American sources show, as expected, a progressive increase in Fe oxidation with decreasing latitude, Antarctic sources show Fe oxidation levels higher than expected in such a cold polar environment, probably because of their very high exposure ages. Results from the TALDICE dust samples are compatible with a South American influence at the site during MIS2 (marine isotopic stage 2, the last and coldest phase of the last glacial period), in particular from Patagonia and Tierra del Fuego. However, a contribution from Australia and/or local Antarctic sources cannot be ruled out. Finally, important changes also occurred during the deglaciation and in the Holocene, when the influence of Antarctic local sources seems to have become progressively more important in recent times. This research is the first successful attempt to extract temporal climatic information from X-ray absorption spectroscopic data of the insoluble mineral dust particles contained in an ice core and shows the high potential of this technique.
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Dec 2018
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B18-Core EXAFS
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Abstract: A new approach to extract accurate information on the Fe oxidation state has been tested on three different Fe-rich amphiboles annealed at 194 °C and 520 °C. The method is based on the analysis of the pre-edge structure of the X-ray absorption spectra at the Fe-K edge. The pre-edge band is deconvolved into four Gaussian components where the integrated intensities of the pairs of lower- and higher-energy bands are related to the ferrous to ferric ion ratio. These Fe3+/Fetot ratios have been compared with those obtained with independent techniques (X-ray diffraction and Mossbauer spectroscopy) on the same samples. The experimental data allowed establishing a calibration curve that is in good agreement with a recent statistical analysis based on spectroscopic data for the same type of minerals. The method could be extended to the analysis of other complex systems containing both Fe3+ and Fe2+ in octahedral coordination or to study the dynamics of iron under non-ambient conditions.
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Dec 2018
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B18-Core EXAFS
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Open Access
Abstract: In this work, we will report applications of the total external X-ray fluorescence (TXRF) station, a prototype assembled at the XLab Frascati laboratory (XlabF) at the INFN National Laboratories of Frascati (INFN LNF). XlabF has been established as a facility to study, design and develop X-ray optics, in particular, polycapillary lenses, as well as to perform X-ray experiments for both elemental analysis and tomography. The combination of low-power conventional sources and policapillary optics allows assembling a prototype that can provide a quasi-parallel intense beam for detailed X-ray spectroscopic analysis of extremely low concentrated samples, down to ng/g. We present elemental analysis results of elements contained in tree rings and of dust stored in deep ice cores. In addition to performing challenging environmental research studies, other experiments aim to characterize novel optics and to evaluate original experimental schemes for X-ray diffraction (XRD), X-ray fluorescence (XRF and TXRF) and X-ray imaging.
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Oct 2018
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B18-Core EXAFS
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G.
Baccolo
,
B.
Delmonte
,
S.
Albani
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C.
Baroni
,
G.
Cibin
,
M.
Frezzotti
,
Dariush
Hampai
,
A.
Marcelli
,
M.
Revel
,
M. C.
Salvatore
,
B.
Stenni
,
V.
Maggi
Diamond Proposal Number(s):
[1984]
Abstract: Ice cores from inner East Antarctica provided some of the longest and most detailed climatic reconstructions and allowed understanding the relationships between atmospheric mineral dust and climate. In this work we present synchrotron‐radiation XRF geochemical data of dust from the TALDICE ice core drilled at Talos Dome, a peripheral ice dome of East Antarctica (Western Ross Sea). Results highlight a dominant southern South American origin for dust at TALDICE during the Last Glacial Maximum, similarly to other sites located further inland onto the polar plateau. On the contrary a different scenario concerns Talos Dome during the Holocene if it is compared to more inner sites. The tight connection between high southern latitudes and Antarctica that characterizes cold climate stages, becomes weaker since the onset of the last climatic transition and throughout the Holocene. The net effect of this process at Talos Dome is a modification of the atmospheric and environmental settings, owing to local Antarctic sources of Victoria Land to gain importance and become the dominant ones. At the same time in inner East Antarctica the provenance of dust remains remote also during Holocene, revealing an evolution of the homogeneous scenario observed in glacial periods. The enhanced sensitivity of peripheral ice sheet sites to local dust sources makes Talos Dome an ideal site to assess the climatic and atmospheric changes of the peripheral sectors of East Antarctica during the current interglacial period.
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Sep 2018
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B18-Core EXAFS
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Diamond Proposal Number(s):
[12031]
Abstract: We investigated the oxidation behaviour of a synthetic potassic-ferro-richterite up to 750 °C by using simultaneous X-ray absorption spectroscopy and X-ray diffraction experiments with synchrotron radiation. From the X-ray diffraction results, we observed an abrupt decrease of cell dimensions at ∼335 °C accompanied by an anomalous increase in the monoclinic cell angle β. From the analysis of the XANES spectra at the iron K-edge, we observed that the structural shrinkage is due to the iron oxidation process, coupled to hydrogen loss, occurring at ∼315 °C, slightly before the cell contraction. Combining these results with previous studies performed on similar samples by single-crystal structure refinement, Mössbauer, high temperature-Fourier transform IR and Raman spectroscopies, we show that the temperature evolution in Fe-amphiboles is a multi-step process. Following the iron oxidation driven by temperature, the structural dynamics in this double-chain silicate is ruled by local strains in the ribbon of iron-filled octahedra, mainly due to the contraction of the M(1) site.
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Aug 2018
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B18-Core EXAFS
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Diamond Proposal Number(s):
[1984]
Open Access
Abstract: The possibility of finding a stratigraphically intact ice sequence with a potential basal age exceeding one million years in Antarctica is giving renewed interest to deep ice coring operations. But the older and deeper the ice, the more impactful are the post-depositional processes that alter and modify the information entrapped within ice layers. Understanding in situ post-depositional processes occurring in the deeper part of ice cores is essential to comprehend how the climatic signals are preserved in deep ice, and consequently how to construct the paleoclimatic records. New techniques and new interpretative tools are required for these purposes. In this respect, the application of synchrotron light to microgram-sized atmospheric dust samples extracted from deep ice cores is extremely promising. We present here preliminary results on two sets of samples retrieved from the Talos Dome Antarctic ice core. A first set is composed by samples from the stratigraphically intact upper part of the core, the second by samples retrieved from the deeper part of the core that is still undated. Two techniques based on synchrotron light allowed us to characterize the dust samples, showing that mineral particles entrapped in the deepest ice layers display altered elemental composition and anomalies concerning iron geochemistry, besides being affected by inter-particle aggregation.
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Aug 2018
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