We have explored the performance of an integrated multianalytical approach to the analysis of a s... more We have explored the performance of an integrated multianalytical approach to the analysis of a series of microsamples of historical lithopone (a coprecipitate of ZnS + BaSO4) produced at the beginning of the 20th century, based on the combination of spectrally- and lifetime-resolved photoluminescence (PL) microscopy imaging and electron paramagnetic resonance (EPR) spectroscopy. Multispectral imaging of the PL emission from microsamples revealed the presence of different luminescence centers emitting in the visible spectrum, which we have hypothesized as trace Cu and Mn impurities unintentionally introduced into the ZnS crystal lattice during synthesis, which act as deep traps for electrons. Time-resolved PL imaging analyses highlighted the microsecond decay-kinetic behavior of the emission, confirming the trap state nature of the luminescence centers. EPR confirmed the presence of Cu and Mn, further providing information on the microenvironment of defects in the ZnS crystalline lattice related to specific paramagnetic ions. The multianalytical approach provides important insights into the historical synthesis of lithophone and will be useful for the rapid screening and mapping of impurities in complex semiconductor pigments and other artists' materials.
ABSTRACT In this work, we propose an integrated approach, based on synchrotron analysis with micr... more ABSTRACT In this work, we propose an integrated approach, based on synchrotron analysis with micrometric spatial resolution and sub-ppm sensitivity and µ-Raman mapping, for investigating impurities and heterogeneous inclusions in historical samples of Zn-based white pigments. Analysis was performed at the LUCIA beamline at the Soleil synchrotron radiation facility for the simultaneous detection of the elemental distribution in powdered samples using mapping micro-X-ray Fluorescence (µ-XRF) and for the investigation of oxidation states and coordination of metals using micro-X-ray Near Edge Absorption (µ-XANES) spectroscopy. The identification of specific molecular signatures and the detection of their spatial distribution throughout samples by laboratory µ-Raman measurements highly supported and completed synchrotron data, allowing the identification of Cr- and Fe- based inclusions in the historical samples. In ZnO pigments, common impurities are due to the production process and include Fe and, depending on samples, Cd, Cl and Pb. In one of the Zn-containing pigment, identified as Lithopone, µ-XRF mapping revealed the presence of Co, both as highly concentrated micrometric inclusions and as traces distributed throughout the pigment.
ABSTRACT The case of the most recent measurement performed at LUNA, the 15N(p,gamma)16O reaction,... more ABSTRACT The case of the most recent measurement performed at LUNA, the 15N(p,gamma)16O reaction, is presented. This reaction, together with the 15N(p,alpha)12C, forms the branching point from the first to the second CNO cycle and the ratio of their respective reaction rates influences the nucleosynthesis yields of 16O, 17O e 17F. In particular, one of the three different campaigns performed by the LUNA collaboration to measure the cross section of this reaction will be discussed. This experiment was performed by impinging a proton beam from the LUNA accelerator with energies ranging from 77 to 350 keV in the centre-of-mass reference frame on a TiN solid target, enriched in 15N to 98%. The gamma-rays following the (p, gamma) reaction were detected by means of an high-efficiency BGO detector.
We have explored the performance of an integrated multianalytical approach to the analysis of a s... more We have explored the performance of an integrated multianalytical approach to the analysis of a series of microsamples of historical lithopone (a coprecipitate of ZnS + BaSO4) produced at the beginning of the 20th century, based on the combination of spectrally- and lifetime-resolved photoluminescence (PL) microscopy imaging and electron paramagnetic resonance (EPR) spectroscopy. Multispectral imaging of the PL emission from microsamples revealed the presence of different luminescence centers emitting in the visible spectrum, which we have hypothesized as trace Cu and Mn impurities unintentionally introduced into the ZnS crystal lattice during synthesis, which act as deep traps for electrons. Time-resolved PL imaging analyses highlighted the microsecond decay-kinetic behavior of the emission, confirming the trap state nature of the luminescence centers. EPR confirmed the presence of Cu and Mn, further providing information on the microenvironment of defects in the ZnS crystalline lattice related to specific paramagnetic ions. The multianalytical approach provides important insights into the historical synthesis of lithophone and will be useful for the rapid screening and mapping of impurities in complex semiconductor pigments and other artists' materials.
ABSTRACT In this work, we propose an integrated approach, based on synchrotron analysis with micr... more ABSTRACT In this work, we propose an integrated approach, based on synchrotron analysis with micrometric spatial resolution and sub-ppm sensitivity and µ-Raman mapping, for investigating impurities and heterogeneous inclusions in historical samples of Zn-based white pigments. Analysis was performed at the LUCIA beamline at the Soleil synchrotron radiation facility for the simultaneous detection of the elemental distribution in powdered samples using mapping micro-X-ray Fluorescence (µ-XRF) and for the investigation of oxidation states and coordination of metals using micro-X-ray Near Edge Absorption (µ-XANES) spectroscopy. The identification of specific molecular signatures and the detection of their spatial distribution throughout samples by laboratory µ-Raman measurements highly supported and completed synchrotron data, allowing the identification of Cr- and Fe- based inclusions in the historical samples. In ZnO pigments, common impurities are due to the production process and include Fe and, depending on samples, Cd, Cl and Pb. In one of the Zn-containing pigment, identified as Lithopone, µ-XRF mapping revealed the presence of Co, both as highly concentrated micrometric inclusions and as traces distributed throughout the pigment.
ABSTRACT The case of the most recent measurement performed at LUNA, the 15N(p,gamma)16O reaction,... more ABSTRACT The case of the most recent measurement performed at LUNA, the 15N(p,gamma)16O reaction, is presented. This reaction, together with the 15N(p,alpha)12C, forms the branching point from the first to the second CNO cycle and the ratio of their respective reaction rates influences the nucleosynthesis yields of 16O, 17O e 17F. In particular, one of the three different campaigns performed by the LUNA collaboration to measure the cross section of this reaction will be discussed. This experiment was performed by impinging a proton beam from the LUNA accelerator with energies ranging from 77 to 350 keV in the centre-of-mass reference frame on a TiN solid target, enriched in 15N to 98%. The gamma-rays following the (p, gamma) reaction were detected by means of an high-efficiency BGO detector.
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