Francesca Turco | Università degli Studi di Torino (original) (raw)
Papers by Francesca Turco
SEM-EDS and XRF analyses of pellets produced with powdery clay and ceramic standards and fired at... more SEM-EDS and XRF analyses of pellets produced with powdery clay and ceramic standards and fired at increasing temperatures showed a systematic overestimation of the abundance of heavier detected elements (K, Ca, Ti and Fe) using the conventional procedure of calibration with massive mineral/glass certified materials followed by normalization of the detected values. Errors were particularly noticeable for samples fired in the typical range of temperatures of archaeological and historical pottery (600–900 °C) and for unfired samples, and were attributed to material porosity. An extremely simple method based on the SEM-BSE image analysis is proposed for the semi-quantitative evaluation of porosity. A remarkable increase of accuracy, especially for SEM-EDS, was evidenced when the calibration is performed using a standard with porosity comparable to the samples, with regard to the pottery temperature range. Conversely, for the analysis of high-fired samples simulating porcelain (1200 °C) no substantial difference was observed with respect to the usual massive minerals/glass calibration. Finally, results showed the unsuitability of calibration performed by means of unfired pellets, for both pottery and porcelains.
Journal of Mass Spectrometry, 2009
The gas-phase reaction of CH(3)(+) with NF(3) was investigated by ion trap mass spectrometry (ITM... more The gas-phase reaction of CH(3)(+) with NF(3) was investigated by ion trap mass spectrometry (ITMS). The observed products include NF(2)(+) and CH(2)F(+). Under the same experimental conditions, SiH(3)(+) reacts with NF(3) and forms up to six ionic products, namely (in order of decreasing efficiency) NF(2)(+), SiH(2)F(+), SiHF(2)(+), SiF(+), SiHF(+), and NHF(+). The GeH(3)(+) cation is instead totally unreactive toward NF(3). The different reactivity of XH(3)(+) (X = C, Si, Ge) toward NF(3) has been rationalized by ab initio calculations performed at the MP2 and coupled cluster level of theory. In the reaction of both CH(3)(+) and SiH(3)(+), the kinetically relevant intermediate is the fluorine-coordinated isomer H(3)X-F-NF(2)(+) (X = C, Si). This species forms from the exoergic attack of XH(3)(+) to one of the F atoms of NF(3) and undergoes dissociation and isomerization processes which eventually result in the experimentally observed products. The nitrogen-coordinated isomers H(3)X-NF(3)(+) (X = C, Si) were located as minimum-energy structures but do not play an active role in the reaction mechanism. The inertness of GeH(3)(+) toward NF(3) is also explained by the endoergic character of the dissociation processes involving the H(3)Ge-F-NF(2)(+) isomer.
Mediterranean Archaeology and Archaeometry
In order to perform a physico-chemical multitechnique characterization, 26 fragments of Red Polis... more In order to perform a physico-chemical multitechnique characterization, 26 fragments of Red Polished ware from the archaeological survey in the Kouris river valley (Limassol district, Cyprus) have been analyzed. Despite the gloss-like macroscopic aspect of the potsherd surfaces, Scanning Electron Microscopy (SEM) morphological observation revealed traces of mechanical polishing on the surfaces and the lack of a slip. Energy Dispersive X-ray (EDX) elemental analyses in both scan and map modes confirmed the absence of differentiation between body and surface composition. Chemometric evaluation on EDX bodies data showed a lack of sub-classification. Mineralogical patterns, obtained by X-Ray Powder Diffraction (XRPD) analysis revealed great variability among samples and the presence of amphiboles in 14 sherds, whose identification as homeblende and riebeckite was confirmed by petrographic examination. The unusual presence of these minerals in a ceramic ware fits with the Kouris valley g...
A multitechnique (SEM-EDX, XRD, TGA) characterization was performed on several materials and arte... more A multitechnique (SEM-EDX, XRD, TGA) characterization was performed on several materials and artefacts from
Old Nisa excavated during the recent Italian–Turkmen archaeological expedition,which involved a large building
in the SW corner of the citadel, formed by rooms utilized as warehouses and workshops. Polygenic conglomerates
archaeologically classified as anhydrites were examined and proved to be highly compatible with all the
studied architectural artefacts (a plaster, a mortar, and a mould), making strongly plausible their identification
as raw materials. Besides, several pigments at different stages of the manufacturing process were examined. A
very complex situation emerged, suggesting the existence of different productive processes. At last, a black cylindrical
object, identified as a seal, but almost completely devoid of engravings, turned out to be made of graphite
and obtained by turning.
The results of the analyses on these materials shed a newlight on the complexity of the manufacturing processes
carried out in Old Nisa in connection with the production of decorative elements for the monumental complex
located inside the citadel.
Archaeometry, 2015
ABSTRACT Around 100 porcelain objects of the 18th century Rossetti, Vische and Vinovo manufacture... more ABSTRACT Around 100 porcelain objects of the 18th century Rossetti, Vische and Vinovo manufactures (Piedmont, Italy) from the Palazzo Madama Museum collection were analysed by means of an X-ray fluorescence portable detector. The present study represents the first chemical characterization of these early (1737–1825) European porcelains. Chemical composition data were submitted to multivariate clustering techniques that underscored a complete classification of the three manufactures and the presence of three subgroups for the Vinovo production. These resulting subgroups did not mirror the classification expected on the basis of the historiographic literature. The overall data pointed to technological continuity not only through all the Vinovo phases but even continuing from the earlier Vische manufacture.
Archaeometry, 2015
ABSTRACT Around 100 porcelain objects of the 18th century Rossetti, Vische and Vinovo manufacture... more ABSTRACT Around 100 porcelain objects of the 18th century Rossetti, Vische and Vinovo manufactures (Piedmont, Italy) from the Palazzo Madama Museum collection were analysed by means of an X-ray fluorescence portable detector. The present study represents the first chemical characterization of these early (1737–1825) European porcelains. Chemical composition data were submitted to multivariate clustering techniques that underscored a complete classification of the three manufactures and the presence of three subgroups for the Vinovo production. These resulting subgroups did not mirror the classification expected on the basis of the historiographic literature. The overall data pointed to technological continuity not only through all the Vinovo phases but even continuing from the earlier Vische manufacture.
1. Introduzione Qualsiasi chimico, insegnante, tecnico e professionista, sa che molti dei suoi ri... more 1. Introduzione Qualsiasi chimico, insegnante, tecnico e professionista, sa che molti dei suoi risultati dovranno essere espressi con una particolare unità di misura, la mole, in riferimento ad una specifica proprietà fisica fondamentale dei sistemi presi in considerazione, la quantità di sostanza (QS). Tuttavia, a leggere gran parte della letteratura didattica – a qualsiasi livello – viene il dubbio che non tutti abbiano veramente riflettuto su ciò di cui stanno parlando: non solo vi sono frequenti, gravissimi errori, epistemologici e metrologici, nelle spiegazioni che riguardano la mole come unità di misura, ma sono praticamente sempre elusi i problemi conoscitivi legati alla comprensione della proprietà fisica che si vuole misurare, la QS appunto. In generale ce la si cava estraendo dalla manica (retorica) un particolare numero, spropositato, che di per sé non ha nulla a che fare con la definizione di mole (anzi: ne dipende!), fissando l'attenzione su una particolare interpre...
Mediterranean Archaeology and Archaeometry
In order to perform a physico-chemical multitechnique characterization, 26 fragments of Red Polis... more In order to perform a physico-chemical multitechnique characterization, 26 fragments of Red Polished ware from the archaeological survey in the Kouris river valley (Limassol district, Cyprus) have been analyzed. Despite the gloss-like macroscopic aspect of the potsherd surfaces, Scanning Electron Microscopy (SEM) morphological observation revealed traces of mechanical polishing on the surfaces and the lack of a slip. Energy Dispersive X-ray (EDX) elemental analyses in both scan and map modes confirmed the absence of differentiation between body and surface composition. Chemometric evaluation on EDX bodies data showed a lack of sub-classification. Mineralogical patterns, obtained by X-Ray Powder Diffraction (XRPD) analysis revealed great variability among samples and the presence of amphiboles in 14 sherds, whose identification as homeblende and riebeckite was confirmed by petrographic examination. The unusual presence of these minerals in a ceramic ware fits with the Kouris valley g...
Nuncius, 2000
The essay is divided in three parts. The first part is dedicated to CJ Pedersen and to his work i... more The essay is divided in three parts. The first part is dedicated to CJ Pedersen and to his work in the Du Pont laboratories. After a brief biography and a description of the research milieu at Du Pont, the narrative follows the discovery of crown ethers, its announcement with the ...
European Journal of Mass Spectrometry, 2011
The positive ion chemistry occurring in SiH(4)/GeF(4) gaseous mixtures was investigated by ion tr... more The positive ion chemistry occurring in SiH(4)/GeF(4) gaseous mixtures was investigated by ion trap mass spectrometry and ab initio theoretical calculations. The GeF(3)(+) cation, the only fragment obtained from ionized GeF(4), was unreactive towards SiH(4). All the primary ions SiH(n)(+) (n = 0-3) react instead with GeF(4) so to form SiF(+) or SiH(2)F(+). The latter species reacts in turn with SiH(4) and GeF(4) so to form SiH(3)(+) and SiHF(2)(+), respectively. The potential energy profiles conceivably involved in these reactions were investigated by ab initio calculations performed at the MP2 and coupled cluster (CCSD(T)) level of theory.
Chemistry - A European Journal, 2011
The xenon-difluoronitrenium ion F(2)N-Xe(+) , a novel xenon-nitrogen species, was obtained in the... more The xenon-difluoronitrenium ion F(2)N-Xe(+) , a novel xenon-nitrogen species, was obtained in the gas phase by the nucleophilic displacement of HF from protonated NF(3) by Xe. According to Møller-Plesset (MP2) and CCSD(T) theoretical calculations, the enthalpy and Gibbs energy changes (ΔH and ΔG) of this process are predicted to be -3 kcal mol(-1) . The conceivable alternative formation of the inserted isomers FN-XeF(+) is instead endothermic by approximately 40-60 kcal mol(-1) and is not attainable under the employed ion-trap mass spectrometric conditions. F(2)N-Xe(+) is theoretically characterized as a weak electrostatic complex between NF(2)(+) and Xe, with a Xe-N bond length of 2.4-2.5 Å, and a dissociation enthalpy and free energy into its constituting fragments of 15 and 8 kcal mol(-1), respectively. F(2)N-Xe(+) is more fragile than the xenon-nitrenium ions (FO(2)S)(2)NXe(+), F(5)SN(H)Xe(+), and F(5)TeN(H)Xe(+) observed in the condensed phase, but it is still stable enough to be observed in the gas phase. Other otherwise elusive xenon-nitrogen species could be obtained under these experimental conditions.
Archaeometry (forthcoming)
Several plasters and mortars from the Middle Bronze Age site of Erimi- Laonin tou Porakou (Cyprus... more Several plasters and mortars from the Middle Bronze Age site of Erimi- Laonin tou Porakou (Cyprus) were analyzed in order to perform a technological characterization. Morphological (SEM), elemental (EDX), mineralogical (XRPD), petrographic (polarized OM, SEM-EDX), thermal (TGA) and spectroscopic (FTIR) techniques were applied.
Plasters and mortars were identified as pyrotechnological lime products, obtained using local raw materials and containing a moderate amount of spatic calcite aggregates. Use of organic fibers was ascertained and a seminal use of a hydraulic additive was evidenced.
International Journal of Mass Spectrometry, 2006
ABSTRACT The study of the gas-phase reactions of the Si+ ions with nitrogen trifluoride (NF3) was... more ABSTRACT The study of the gas-phase reactions of the Si+ ions with nitrogen trifluoride (NF3) was performed by quadrupole ion trap mass spectrometry and ab initio calculations. Experimental results display a thermodynamically favoured reaction cascade starting from the reactants corresponding to multiple fluorine abstraction, which ultimately yields neutral fluorosilane by fluoride abstraction. A parallel, slightly endothermic channel is observed starting from the reactants and generating the NF2+ and SiF products. The study of the potential energy hypersurface of the Si+(2P) + NF3 system evidenced the initial formation of the N-coordinated Si+–NF3 adduct. Subsequent rearrangements and atom migrations lead to the FSi+–NF2 isomer, whose dissociation yields SiF+ and NF2 as products. Theoretical energy profiles show that this pathway is strongly exothermic (about −100 kcal mol−1) and that the dissociation of the FSi+–NF2 species to the endothermic (+6 kcal mol−1) channel products (NF2+ and SiF) is extremely unlikely for ground-state reactants.
International Journal of Mass Spectrometry, 2004
Ion/molecule reactions in the C 3 H 4 /NH 3 and SiH 4 /C 3 H 4 /NH 3 gaseous mixtures were invest... more Ion/molecule reactions in the C 3 H 4 /NH 3 and SiH 4 /C 3 H 4 /NH 3 gaseous mixtures were investigated by ion trap mass spectrometry, with the aim of finding the best experimental conditions for formation and growth of ion clusters containing silicon, carbon and nitrogen. These species may play an important role in the deposition of silicon carbides doped with nitrogen by X-ray assisted chemical vapour deposition methods from suitable systems. In the study of the C 3 H 4 /NH 3 mixture the main reaction pathways leading to formation of C/N-containing species were identified. Few mixed C/N ions are formed, with low formation rates, and their overall abundance reaches only 7% of the total ion current after 1 s reaction time. In the ternary mixture, mixed Si-containing ions were found to be the most efficient precursors of ternary ion species. The SiC n H q + (n = 1-3; q = 2-5, 7) ions efficiently react with ammonia, but only in few cases these reactions lead to formation of ternary mixed ions as hydrocarbon loss mostly occurs with formation of binary SiNH q + (q = 2, 4) ions. On the other hand, propyne was found to be very reactive and several ternary mixed ions were formed from its reactions with SiNH q + (q = 2, 4) and SiCNH q + (q = 6, 8) ions. The total abundance of ternary mixed ions reaches 20% of the total ion current after 1 s reaction time. (R. Rabezzana). ation and clustering reactions leading to the precursors of the final solid is very useful in order to find the relationship between the partial pressures of the reagent gases and the abundance of Si in the amorphous polymers. The activity of semiconductor materials may be improved by doping them with phosphorus or nitrogen, and this is the reason why the SiH 4 /PH 3 and SiH 4 /NH 3 mixtures have been previously investigated . This paper reports on the reactivity of the silane/propyne/ ammonia ternary system, studied with the aim of checking the possibility of synthesizing a material containing silicon carbide doped with nitrogen in a single reaction step. The investigation of a ternary mixture requires the preliminary knowledge of the reaction mechanisms in all related binary mixtures. Silane/ammonia and silane/propyne mixtures have been investigated previously , while the study of the propyne/ammonia system is reported in this paper.
International Journal of Mass Spectrometry, 2007
... involving NF 3 and NF x + (x = 13). Finally, the chemical inertness of NF 3 toward the major... more ... involving NF 3 and NF x + (x = 13). Finally, the chemical inertness of NF 3 toward the major neutral tropospheric oxidants [8] stimulates interest in the conceivable occurrence of ionic processes promoted, for example, by inorganic aerosols or by corona discharges during ...
Journal of Mass Spectrometry, 2004
The gas-phase ion chemistry of propyne–phosphine and silane–propyne–phosphine mixtures was studie... more The gas-phase ion chemistry of propyne–phosphine and silane–propyne–phosphine mixtures was studied by ion trap mass spectrometry. For the binary mixture, the effect of different partial pressures of the reagents on the yield of C and P-containing ions was evaluated. Reaction sequences and rate constants were determined and reaction efficiencies were calculated from comparison of experimental and collisional rate constants. In the ternary silane–propyne–phosphine systems, the reaction pathways leading to formation of SimCnPpHq+ ions were determined and the rate constants of the most important steps were measured. For some ion species, selected by double isolation procedures (MS/MS), the low ion abundances prevented determination of the reaction rate constants. Si, C and P-containing ions are mainly produced in reactions of SimPpHq+ ions with propyne, while the reactivity of the SimCnHq+ ions towards PH3 and of the CnPpHq+ ions towards SiH4 is very low. The formation of hydrogenated SiCP ions is interesting for their possible role as precursors of amorphous silicon carbides doped with phosphorus, obtained in a single step, by deposition from properly activated silane–propyne–phosphine mixtures. Copyright © 2004 John Wiley & Sons, Ltd.
Journal of Mass Spectrometry, 2008
The ion–molecule reactions occurring in GeH4/NF3, GeH4/SF6, and GeH4/SiF4 gaseous mixtures have b... more The ion–molecule reactions occurring in GeH4/NF3, GeH4/SF6, and GeH4/SiF4 gaseous mixtures have been investigated by ion trap mass spectrometry and ab initio calculations. While the NFx+ (x = 1–3) react with GeH4 mainly by the exothermic charge transfer, the open-shell Ge+ and GeH2+ undergo the efficient F-atom abstraction from NF3 and form GeF+ and FGeH2+ as the only ionic products. The mechanisms of these two processes are quite similar and involve the formation of the fluorine-coordinated complexes GeFNF2+ and H2GeFNF2+, their subsequent crossing to the significantly more stable isomers FGeNF2+ and FGeH2NF2+, and the eventual dissociation of these ions into GeF+ (or FGeH2+) and NF2. The closed-shell GeH+ and GeH3+ are instead much less reactive towards NF3, and the only observed process is the less efficient formation of GeF+ from GeH+. The theoretical investigation of this unusual H/F exchange reaction suggests the involvement of vibrationally-hot GeH+. Passing from NF3 to SF6 and SiF4, the average strength of the MF bond increases from 70 to 79 and 142 kcal mol−1, and in fact the only process observed by reacting GeHn+ (n = 0–3) with SF6 and SiF4 is the little efficient F-atom abstraction from SF6 by Ge+. Irrespective of the experimental conditions, we did not observe any ionic product of GeN, GeS, or GeSi connectivity. This is in line with the previously observed exclusive formation of GeF+ from the reaction between Ge+ and CF compounds such as CH3F. Additionally observed processes include in particular the conceivable formation of the elusive thiohypofluorous acid FSH from the reaction between SF+ and GeH4. Copyright © 2008 John Wiley & Sons, Ltd.
International Journal of Mass Spectrometry, 2007
The gas phase ion chemistry of diborane and of silane/diborane mixtures was studied by ion trap m... more The gas phase ion chemistry of diborane and of silane/diborane mixtures was studied by ion trap mass spectrometry (ITMS), in both positive and negative ionization mode. Positive ion/molecule reactions in diborane mainly proceed through H2 or BH3 loss and lead to formation of B hydride clusters containing up to six B atoms, while in negative ionization clustering reactions proceed to
Rapid Communications in Mass Spectrometry, 2005
Gas-phase anion/molecule reactions of germanium hydride were studied by quadrupole ion trap (QIT)... more Gas-phase anion/molecule reactions of germanium hydride were studied by quadrupole ion trap (QIT) mass spectrometry. Under chemical ionization (CI) conditions and with a sample pressure of about 5.0 × 10−5 Torr, clustering reactions proceed up to the formation of Ge5H ion clusters. With increasing cluster size, the most abundant ion species are those with the lowest content of hydrogen. Reaction sequences obtained by ion isolation were determined for primary, secondary and tertiary germane ions, and reaction enthalpies were calculated for reactions of primary ions. Ion/neutral condensation processes followed by single and double dehydrogenation are by far the most important reactions; moreover, isotope scrambling is observed for almost every reactant ion. These results are in good agreement with previously published data and indicate that germane negative ions are quite efficient in formation and growth of ionic clusters, which can be considered suitable precursors of amorphous solid hydrogenated germanium used in the semiconductor field. Copyright © 2005 John Wiley & Sons, Ltd.
SEM-EDS and XRF analyses of pellets produced with powdery clay and ceramic standards and fired at... more SEM-EDS and XRF analyses of pellets produced with powdery clay and ceramic standards and fired at increasing temperatures showed a systematic overestimation of the abundance of heavier detected elements (K, Ca, Ti and Fe) using the conventional procedure of calibration with massive mineral/glass certified materials followed by normalization of the detected values. Errors were particularly noticeable for samples fired in the typical range of temperatures of archaeological and historical pottery (600–900 °C) and for unfired samples, and were attributed to material porosity. An extremely simple method based on the SEM-BSE image analysis is proposed for the semi-quantitative evaluation of porosity. A remarkable increase of accuracy, especially for SEM-EDS, was evidenced when the calibration is performed using a standard with porosity comparable to the samples, with regard to the pottery temperature range. Conversely, for the analysis of high-fired samples simulating porcelain (1200 °C) no substantial difference was observed with respect to the usual massive minerals/glass calibration. Finally, results showed the unsuitability of calibration performed by means of unfired pellets, for both pottery and porcelains.
Journal of Mass Spectrometry, 2009
The gas-phase reaction of CH(3)(+) with NF(3) was investigated by ion trap mass spectrometry (ITM... more The gas-phase reaction of CH(3)(+) with NF(3) was investigated by ion trap mass spectrometry (ITMS). The observed products include NF(2)(+) and CH(2)F(+). Under the same experimental conditions, SiH(3)(+) reacts with NF(3) and forms up to six ionic products, namely (in order of decreasing efficiency) NF(2)(+), SiH(2)F(+), SiHF(2)(+), SiF(+), SiHF(+), and NHF(+). The GeH(3)(+) cation is instead totally unreactive toward NF(3). The different reactivity of XH(3)(+) (X = C, Si, Ge) toward NF(3) has been rationalized by ab initio calculations performed at the MP2 and coupled cluster level of theory. In the reaction of both CH(3)(+) and SiH(3)(+), the kinetically relevant intermediate is the fluorine-coordinated isomer H(3)X-F-NF(2)(+) (X = C, Si). This species forms from the exoergic attack of XH(3)(+) to one of the F atoms of NF(3) and undergoes dissociation and isomerization processes which eventually result in the experimentally observed products. The nitrogen-coordinated isomers H(3)X-NF(3)(+) (X = C, Si) were located as minimum-energy structures but do not play an active role in the reaction mechanism. The inertness of GeH(3)(+) toward NF(3) is also explained by the endoergic character of the dissociation processes involving the H(3)Ge-F-NF(2)(+) isomer.
Mediterranean Archaeology and Archaeometry
In order to perform a physico-chemical multitechnique characterization, 26 fragments of Red Polis... more In order to perform a physico-chemical multitechnique characterization, 26 fragments of Red Polished ware from the archaeological survey in the Kouris river valley (Limassol district, Cyprus) have been analyzed. Despite the gloss-like macroscopic aspect of the potsherd surfaces, Scanning Electron Microscopy (SEM) morphological observation revealed traces of mechanical polishing on the surfaces and the lack of a slip. Energy Dispersive X-ray (EDX) elemental analyses in both scan and map modes confirmed the absence of differentiation between body and surface composition. Chemometric evaluation on EDX bodies data showed a lack of sub-classification. Mineralogical patterns, obtained by X-Ray Powder Diffraction (XRPD) analysis revealed great variability among samples and the presence of amphiboles in 14 sherds, whose identification as homeblende and riebeckite was confirmed by petrographic examination. The unusual presence of these minerals in a ceramic ware fits with the Kouris valley g...
A multitechnique (SEM-EDX, XRD, TGA) characterization was performed on several materials and arte... more A multitechnique (SEM-EDX, XRD, TGA) characterization was performed on several materials and artefacts from
Old Nisa excavated during the recent Italian–Turkmen archaeological expedition,which involved a large building
in the SW corner of the citadel, formed by rooms utilized as warehouses and workshops. Polygenic conglomerates
archaeologically classified as anhydrites were examined and proved to be highly compatible with all the
studied architectural artefacts (a plaster, a mortar, and a mould), making strongly plausible their identification
as raw materials. Besides, several pigments at different stages of the manufacturing process were examined. A
very complex situation emerged, suggesting the existence of different productive processes. At last, a black cylindrical
object, identified as a seal, but almost completely devoid of engravings, turned out to be made of graphite
and obtained by turning.
The results of the analyses on these materials shed a newlight on the complexity of the manufacturing processes
carried out in Old Nisa in connection with the production of decorative elements for the monumental complex
located inside the citadel.
Archaeometry, 2015
ABSTRACT Around 100 porcelain objects of the 18th century Rossetti, Vische and Vinovo manufacture... more ABSTRACT Around 100 porcelain objects of the 18th century Rossetti, Vische and Vinovo manufactures (Piedmont, Italy) from the Palazzo Madama Museum collection were analysed by means of an X-ray fluorescence portable detector. The present study represents the first chemical characterization of these early (1737–1825) European porcelains. Chemical composition data were submitted to multivariate clustering techniques that underscored a complete classification of the three manufactures and the presence of three subgroups for the Vinovo production. These resulting subgroups did not mirror the classification expected on the basis of the historiographic literature. The overall data pointed to technological continuity not only through all the Vinovo phases but even continuing from the earlier Vische manufacture.
Archaeometry, 2015
ABSTRACT Around 100 porcelain objects of the 18th century Rossetti, Vische and Vinovo manufacture... more ABSTRACT Around 100 porcelain objects of the 18th century Rossetti, Vische and Vinovo manufactures (Piedmont, Italy) from the Palazzo Madama Museum collection were analysed by means of an X-ray fluorescence portable detector. The present study represents the first chemical characterization of these early (1737–1825) European porcelains. Chemical composition data were submitted to multivariate clustering techniques that underscored a complete classification of the three manufactures and the presence of three subgroups for the Vinovo production. These resulting subgroups did not mirror the classification expected on the basis of the historiographic literature. The overall data pointed to technological continuity not only through all the Vinovo phases but even continuing from the earlier Vische manufacture.
1. Introduzione Qualsiasi chimico, insegnante, tecnico e professionista, sa che molti dei suoi ri... more 1. Introduzione Qualsiasi chimico, insegnante, tecnico e professionista, sa che molti dei suoi risultati dovranno essere espressi con una particolare unità di misura, la mole, in riferimento ad una specifica proprietà fisica fondamentale dei sistemi presi in considerazione, la quantità di sostanza (QS). Tuttavia, a leggere gran parte della letteratura didattica – a qualsiasi livello – viene il dubbio che non tutti abbiano veramente riflettuto su ciò di cui stanno parlando: non solo vi sono frequenti, gravissimi errori, epistemologici e metrologici, nelle spiegazioni che riguardano la mole come unità di misura, ma sono praticamente sempre elusi i problemi conoscitivi legati alla comprensione della proprietà fisica che si vuole misurare, la QS appunto. In generale ce la si cava estraendo dalla manica (retorica) un particolare numero, spropositato, che di per sé non ha nulla a che fare con la definizione di mole (anzi: ne dipende!), fissando l'attenzione su una particolare interpre...
Mediterranean Archaeology and Archaeometry
In order to perform a physico-chemical multitechnique characterization, 26 fragments of Red Polis... more In order to perform a physico-chemical multitechnique characterization, 26 fragments of Red Polished ware from the archaeological survey in the Kouris river valley (Limassol district, Cyprus) have been analyzed. Despite the gloss-like macroscopic aspect of the potsherd surfaces, Scanning Electron Microscopy (SEM) morphological observation revealed traces of mechanical polishing on the surfaces and the lack of a slip. Energy Dispersive X-ray (EDX) elemental analyses in both scan and map modes confirmed the absence of differentiation between body and surface composition. Chemometric evaluation on EDX bodies data showed a lack of sub-classification. Mineralogical patterns, obtained by X-Ray Powder Diffraction (XRPD) analysis revealed great variability among samples and the presence of amphiboles in 14 sherds, whose identification as homeblende and riebeckite was confirmed by petrographic examination. The unusual presence of these minerals in a ceramic ware fits with the Kouris valley g...
Nuncius, 2000
The essay is divided in three parts. The first part is dedicated to CJ Pedersen and to his work i... more The essay is divided in three parts. The first part is dedicated to CJ Pedersen and to his work in the Du Pont laboratories. After a brief biography and a description of the research milieu at Du Pont, the narrative follows the discovery of crown ethers, its announcement with the ...
European Journal of Mass Spectrometry, 2011
The positive ion chemistry occurring in SiH(4)/GeF(4) gaseous mixtures was investigated by ion tr... more The positive ion chemistry occurring in SiH(4)/GeF(4) gaseous mixtures was investigated by ion trap mass spectrometry and ab initio theoretical calculations. The GeF(3)(+) cation, the only fragment obtained from ionized GeF(4), was unreactive towards SiH(4). All the primary ions SiH(n)(+) (n = 0-3) react instead with GeF(4) so to form SiF(+) or SiH(2)F(+). The latter species reacts in turn with SiH(4) and GeF(4) so to form SiH(3)(+) and SiHF(2)(+), respectively. The potential energy profiles conceivably involved in these reactions were investigated by ab initio calculations performed at the MP2 and coupled cluster (CCSD(T)) level of theory.
Chemistry - A European Journal, 2011
The xenon-difluoronitrenium ion F(2)N-Xe(+) , a novel xenon-nitrogen species, was obtained in the... more The xenon-difluoronitrenium ion F(2)N-Xe(+) , a novel xenon-nitrogen species, was obtained in the gas phase by the nucleophilic displacement of HF from protonated NF(3) by Xe. According to Møller-Plesset (MP2) and CCSD(T) theoretical calculations, the enthalpy and Gibbs energy changes (ΔH and ΔG) of this process are predicted to be -3 kcal mol(-1) . The conceivable alternative formation of the inserted isomers FN-XeF(+) is instead endothermic by approximately 40-60 kcal mol(-1) and is not attainable under the employed ion-trap mass spectrometric conditions. F(2)N-Xe(+) is theoretically characterized as a weak electrostatic complex between NF(2)(+) and Xe, with a Xe-N bond length of 2.4-2.5 Å, and a dissociation enthalpy and free energy into its constituting fragments of 15 and 8 kcal mol(-1), respectively. F(2)N-Xe(+) is more fragile than the xenon-nitrenium ions (FO(2)S)(2)NXe(+), F(5)SN(H)Xe(+), and F(5)TeN(H)Xe(+) observed in the condensed phase, but it is still stable enough to be observed in the gas phase. Other otherwise elusive xenon-nitrogen species could be obtained under these experimental conditions.
Archaeometry (forthcoming)
Several plasters and mortars from the Middle Bronze Age site of Erimi- Laonin tou Porakou (Cyprus... more Several plasters and mortars from the Middle Bronze Age site of Erimi- Laonin tou Porakou (Cyprus) were analyzed in order to perform a technological characterization. Morphological (SEM), elemental (EDX), mineralogical (XRPD), petrographic (polarized OM, SEM-EDX), thermal (TGA) and spectroscopic (FTIR) techniques were applied.
Plasters and mortars were identified as pyrotechnological lime products, obtained using local raw materials and containing a moderate amount of spatic calcite aggregates. Use of organic fibers was ascertained and a seminal use of a hydraulic additive was evidenced.
International Journal of Mass Spectrometry, 2006
ABSTRACT The study of the gas-phase reactions of the Si+ ions with nitrogen trifluoride (NF3) was... more ABSTRACT The study of the gas-phase reactions of the Si+ ions with nitrogen trifluoride (NF3) was performed by quadrupole ion trap mass spectrometry and ab initio calculations. Experimental results display a thermodynamically favoured reaction cascade starting from the reactants corresponding to multiple fluorine abstraction, which ultimately yields neutral fluorosilane by fluoride abstraction. A parallel, slightly endothermic channel is observed starting from the reactants and generating the NF2+ and SiF products. The study of the potential energy hypersurface of the Si+(2P) + NF3 system evidenced the initial formation of the N-coordinated Si+–NF3 adduct. Subsequent rearrangements and atom migrations lead to the FSi+–NF2 isomer, whose dissociation yields SiF+ and NF2 as products. Theoretical energy profiles show that this pathway is strongly exothermic (about −100 kcal mol−1) and that the dissociation of the FSi+–NF2 species to the endothermic (+6 kcal mol−1) channel products (NF2+ and SiF) is extremely unlikely for ground-state reactants.
International Journal of Mass Spectrometry, 2004
Ion/molecule reactions in the C 3 H 4 /NH 3 and SiH 4 /C 3 H 4 /NH 3 gaseous mixtures were invest... more Ion/molecule reactions in the C 3 H 4 /NH 3 and SiH 4 /C 3 H 4 /NH 3 gaseous mixtures were investigated by ion trap mass spectrometry, with the aim of finding the best experimental conditions for formation and growth of ion clusters containing silicon, carbon and nitrogen. These species may play an important role in the deposition of silicon carbides doped with nitrogen by X-ray assisted chemical vapour deposition methods from suitable systems. In the study of the C 3 H 4 /NH 3 mixture the main reaction pathways leading to formation of C/N-containing species were identified. Few mixed C/N ions are formed, with low formation rates, and their overall abundance reaches only 7% of the total ion current after 1 s reaction time. In the ternary mixture, mixed Si-containing ions were found to be the most efficient precursors of ternary ion species. The SiC n H q + (n = 1-3; q = 2-5, 7) ions efficiently react with ammonia, but only in few cases these reactions lead to formation of ternary mixed ions as hydrocarbon loss mostly occurs with formation of binary SiNH q + (q = 2, 4) ions. On the other hand, propyne was found to be very reactive and several ternary mixed ions were formed from its reactions with SiNH q + (q = 2, 4) and SiCNH q + (q = 6, 8) ions. The total abundance of ternary mixed ions reaches 20% of the total ion current after 1 s reaction time. (R. Rabezzana). ation and clustering reactions leading to the precursors of the final solid is very useful in order to find the relationship between the partial pressures of the reagent gases and the abundance of Si in the amorphous polymers. The activity of semiconductor materials may be improved by doping them with phosphorus or nitrogen, and this is the reason why the SiH 4 /PH 3 and SiH 4 /NH 3 mixtures have been previously investigated . This paper reports on the reactivity of the silane/propyne/ ammonia ternary system, studied with the aim of checking the possibility of synthesizing a material containing silicon carbide doped with nitrogen in a single reaction step. The investigation of a ternary mixture requires the preliminary knowledge of the reaction mechanisms in all related binary mixtures. Silane/ammonia and silane/propyne mixtures have been investigated previously , while the study of the propyne/ammonia system is reported in this paper.
International Journal of Mass Spectrometry, 2007
... involving NF 3 and NF x + (x = 13). Finally, the chemical inertness of NF 3 toward the major... more ... involving NF 3 and NF x + (x = 13). Finally, the chemical inertness of NF 3 toward the major neutral tropospheric oxidants [8] stimulates interest in the conceivable occurrence of ionic processes promoted, for example, by inorganic aerosols or by corona discharges during ...
Journal of Mass Spectrometry, 2004
The gas-phase ion chemistry of propyne–phosphine and silane–propyne–phosphine mixtures was studie... more The gas-phase ion chemistry of propyne–phosphine and silane–propyne–phosphine mixtures was studied by ion trap mass spectrometry. For the binary mixture, the effect of different partial pressures of the reagents on the yield of C and P-containing ions was evaluated. Reaction sequences and rate constants were determined and reaction efficiencies were calculated from comparison of experimental and collisional rate constants. In the ternary silane–propyne–phosphine systems, the reaction pathways leading to formation of SimCnPpHq+ ions were determined and the rate constants of the most important steps were measured. For some ion species, selected by double isolation procedures (MS/MS), the low ion abundances prevented determination of the reaction rate constants. Si, C and P-containing ions are mainly produced in reactions of SimPpHq+ ions with propyne, while the reactivity of the SimCnHq+ ions towards PH3 and of the CnPpHq+ ions towards SiH4 is very low. The formation of hydrogenated SiCP ions is interesting for their possible role as precursors of amorphous silicon carbides doped with phosphorus, obtained in a single step, by deposition from properly activated silane–propyne–phosphine mixtures. Copyright © 2004 John Wiley & Sons, Ltd.
Journal of Mass Spectrometry, 2008
The ion–molecule reactions occurring in GeH4/NF3, GeH4/SF6, and GeH4/SiF4 gaseous mixtures have b... more The ion–molecule reactions occurring in GeH4/NF3, GeH4/SF6, and GeH4/SiF4 gaseous mixtures have been investigated by ion trap mass spectrometry and ab initio calculations. While the NFx+ (x = 1–3) react with GeH4 mainly by the exothermic charge transfer, the open-shell Ge+ and GeH2+ undergo the efficient F-atom abstraction from NF3 and form GeF+ and FGeH2+ as the only ionic products. The mechanisms of these two processes are quite similar and involve the formation of the fluorine-coordinated complexes GeFNF2+ and H2GeFNF2+, their subsequent crossing to the significantly more stable isomers FGeNF2+ and FGeH2NF2+, and the eventual dissociation of these ions into GeF+ (or FGeH2+) and NF2. The closed-shell GeH+ and GeH3+ are instead much less reactive towards NF3, and the only observed process is the less efficient formation of GeF+ from GeH+. The theoretical investigation of this unusual H/F exchange reaction suggests the involvement of vibrationally-hot GeH+. Passing from NF3 to SF6 and SiF4, the average strength of the MF bond increases from 70 to 79 and 142 kcal mol−1, and in fact the only process observed by reacting GeHn+ (n = 0–3) with SF6 and SiF4 is the little efficient F-atom abstraction from SF6 by Ge+. Irrespective of the experimental conditions, we did not observe any ionic product of GeN, GeS, or GeSi connectivity. This is in line with the previously observed exclusive formation of GeF+ from the reaction between Ge+ and CF compounds such as CH3F. Additionally observed processes include in particular the conceivable formation of the elusive thiohypofluorous acid FSH from the reaction between SF+ and GeH4. Copyright © 2008 John Wiley & Sons, Ltd.
International Journal of Mass Spectrometry, 2007
The gas phase ion chemistry of diborane and of silane/diborane mixtures was studied by ion trap m... more The gas phase ion chemistry of diborane and of silane/diborane mixtures was studied by ion trap mass spectrometry (ITMS), in both positive and negative ionization mode. Positive ion/molecule reactions in diborane mainly proceed through H2 or BH3 loss and lead to formation of B hydride clusters containing up to six B atoms, while in negative ionization clustering reactions proceed to
Rapid Communications in Mass Spectrometry, 2005
Gas-phase anion/molecule reactions of germanium hydride were studied by quadrupole ion trap (QIT)... more Gas-phase anion/molecule reactions of germanium hydride were studied by quadrupole ion trap (QIT) mass spectrometry. Under chemical ionization (CI) conditions and with a sample pressure of about 5.0 × 10−5 Torr, clustering reactions proceed up to the formation of Ge5H ion clusters. With increasing cluster size, the most abundant ion species are those with the lowest content of hydrogen. Reaction sequences obtained by ion isolation were determined for primary, secondary and tertiary germane ions, and reaction enthalpies were calculated for reactions of primary ions. Ion/neutral condensation processes followed by single and double dehydrogenation are by far the most important reactions; moreover, isotope scrambling is observed for almost every reactant ion. These results are in good agreement with previously published data and indicate that germane negative ions are quite efficient in formation and growth of ionic clusters, which can be considered suitable precursors of amorphous solid hydrogenated germanium used in the semiconductor field. Copyright © 2005 John Wiley & Sons, Ltd.